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Crowd-sourced air quality studies: A review of the literature & portable sensors

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Abstract

Development of low-cost, portable, and low-power devices for monitoring airborne pollutants is a crucial step towards developing improved air quality models and better quantitating the health effects of human and animal exposure. This review article summarizes recent developments in the field within the context of the establishment/expansion of high spatial and temporal resolution air quality monitoring networks. Current ‘crowd-sourced’ monitoring efforts are summarized, and recent advances in chemical sensors required for these networks are described. No ‘perfect’ sensing platform, that meets the requirements of low-cost, portability, selectivity, and sensitivity has yet been achieved. This highlights the need for investment in the fundamental analytical chemistry of the sensing platforms required to achieve such ‘smart-cities.’ Such investment should include the development of new sensor technologies, and provide for calibration and performance validation for systems enacted. In addition to summarizing the current state-of-the-art, reflections on future needs are also offered.

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... This work uses the sensor of gases model MQ-2, which is a sensor type MOS and has an operational principle based on the variation of its internal electrical resistance according to the gas concentration around it. In fact, there are different types of gas sensors, but the type of MOS is interesting for educational approaches because of its low cost, interesting operational principles and simplicity of interfacing [3][4][5]. ...
... Figure 1 exemplifies the MQ-2 structure, which is typical for all sensor type MOS. Tin dioxide (SnO 2 ) works as the sensing element, which presents a high electrical resistance (Rs) in the absence of gases (clean air) and a low resistance in their presence [4]. ...
... Consequently, Rs increases in the clean air and it encumbers the current flow through it. However, the level of absorbed oxygen decreases in the presence of gases, and it releases the electrons to allow a current flow through SnO 2 [3][4][5][6]. In fact, during the crystal growth, oxygen vacancies are created in the SnO 2 crystal lattice to compose it in the non-stoichiometric form SnO X , where 1 < x < 2, which facilitates the easy adsorption of oxygen at its surface and the operation as a sensor [8][9][10]. ...
... User-friendly interface and low maintenance requirement makes them an easy-to-use and convenient device (Castell et al., 2013). Scalability of pollutant detection is also an advantage and can supplement the already existing air quality monitoring networks (Castell et al., 2013;Thompson, 2016;Santos et al., 2018). Their portability allows personal pollutant monitoring and, subsequently, one can choose less polluted routes while commuting (Castell et al., 2013). ...
... Their portability allows personal pollutant monitoring and, subsequently, one can choose less polluted routes while commuting (Castell et al., 2013). The use of low-cost sensors also makes room for citizens to engage in community-driven science, i.e., people can contribute by collecting air quality data (Snyder et al., 2013;White et al., 2012;Thompson, 2016). ...
... With the rapidly increasing number of studies, projects and grey literature based on low-cost sensors, information got scattered. Although there were some review publications related to low-cost sensors and IAQ (Kumar et al., 2016a(Kumar et al., , 2016bThompson, 2016;Morawska et al., 2018), as far as the authors' knowledge goes, there was no review study published focusing on the studies that specified the characteristics of low-cost IAQ monitoring device development, such as: i) integration of relevant low-cost sensors; ii) processor for data acquisition; iii) analogue to digital convertor for the measurements; iv) data logging and transmission; v) software layer; vi) hardware enclosure; and vii) device performance assessment. It is a crucial but overlooked gap in the literature and this study aims to review the components used by various studies while developing a novel IAQ monitoring device and evaluate which components (especially sensors) perform the best. ...
Article
The use of low-cost sensor technology to monitor air pollution has made remarkable strides in the last decade. The development of low-cost devices to monitor air quality in indoor environments can be used to understand the behaviour of indoor air pollutants and potentially impact on the reduction of related health impacts. These user-friendly devices are portable, require low-maintenance, and can enable near real-time, continuous monitoring. They can also contribute to citizen science projects and community-driven science. However, low-cost sensors have often been associated with design compromises that hamper data reliability. Moreover, with the rapidly increasing number of studies, projects, and grey literature based on low-cost sensors, information got scattered. Intending to identify and review scientifically validated literature on this topic, this study critically summarizes the recent research pertinent to the development of indoor air quality monitoring devices using low-cost sensors. The method employed for this review was a thorough search of three scientific databases, namely: ScienceDirect, IEEE, and Scopus. A total of 891 titles published since 2012 were found and scanned for relevance. Finally, 41 research articles consisting of 35 unique device development projects were reviewed with a particular emphasis on device development: calibration and performance of sensors, the processor used, data storage and communication, and the availability of real-time remote access of sensor data. The most prominent finding of the study showed a lack of studies consisting of sensor performance as only 16 out of 35 projects performed calibration/validation of sensors. An even fewer number of studies conducted these tests with a reference instrument. Hence, a need for more studies with calibration, credible validation, and standardization of sensor performance and assessment is recommended for subsequent research.
... An increasing number of evaluations of MCS and LCS as well as of networks based on such sensors are being performed and conclusions are available from these studies such as Thompson (2016), Morawska et al. suppl., (2018), Karagulian et al., (2019). It is well-known that these sensors suffer from drift and aging (Brattich et al., 2020). ...
... Applications of LCS as well as networks based on such sensors have increased over the past decade (e.g., Thompson 2016, Karagulian et al., 2019, Schäfer et al., 2021. These applications have also highlighted the need for proper evaluation, quality control and calibration of these sensors. ...
Preprint
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This review provides a community's perspective on air quality research focussing mainly on developments over the past decade. The article provides perspectives on current and future challenges as well as research needs for selected key topics. While this paper is not an exhaustive review of all research areas in the field of air quality, we have selected key topics that we feel are important from air quality research and policy perspectives. After providing a short historical overview, this review 40 focuses on improvements in characterising sources and emissions of air pollution, new air quality observations and instrumentation, advances in air quality prediction and forecasting, understanding interactions of air quality with meteorology https://doi.org/10.5194/acp-2021-581 Preprint. Discussion started: 23 September 2021 c Author(s) 2021. CC BY 4.0 License. 2 and climate, exposure and health assessment, and air quality management and policy. In conducting the review, specific objectives were (i) to address current developments that push the boundaries of air quality research forward, (ii) to highlight the emerging prominent gaps of knowledge in air quality research and (iii) and to make recommendations to guide the direction 45 for future research within the wider community. This review also identifies areas of particular importance for air quality policy. The original concept of this review was borne at the International Conference on Air Quality 2020 (held online due to the COVID 19 restrictions during 18-26 May 2020), but the article incorporates a wider landscape of research literature within the field of air quality science. On air pollution emissions the review highlights, in particular, the need to reduce uncertainties in emissions from diffuse sources, particulate matter chemical components, shipping emissions and the importance of considering 50 both indoor and outdoor sources. There is a growing need to have integrated air pollution and related observations from both ground based and remote sensing instruments, including especially those on satellites. The research should also capitalize on the growing area of lower cost sensors, while ensuring a quality of the measurements which are regulated by guidelines. Connecting various physical scales in air quality modelling is still a continual issue, with cities being affected by air pollution gradients at local scales and by long range transport. At the same time, one should allow for the impacts from climate change 55 on a longer timescale. Earth system modelling offers considerable potential by providing a consistent framework for treating scales and processes, especially where there are significant feedbacks, such as those related to aerosols, chemistry and meteorology. Assessment of exposure to air pollution should consider both the impacts of indoor and outdoor emissions, as well as application of more sophisticated, dynamic modelling approaches to predict concentrations of air pollutants in both environments. With particulate matter being one of the most important pollutants for health, research is indicating the urgent 60 need to understand, in particular, the role of particle number and chemical components in terms of health impact, which in turn requires improved emission inventories and models for predicting high resolution distributions of these metrics over cities. The review also examines, how air pollution management needs to adapt to the above-mentioned new challenges and briefly considers the implications from the COVID-19 pandemic for air quality. Finally, we provide recommendations for air quality research and support for policy. 65 Dedication We wish to dedicate this article to the following eminent scientists who made immense contributions to the science of air quality and its impacts: Paul
... A necessary condition for using catalytic bead sensors is the presence of oxygen, since it is required for the burning process. With less than 10 seconds, the response time of catalytic bead sensors is relatively short [15]. The average lifetime of these sensors is commonly 5 years [16], which can be significantly reduced by catalyst poisoning, whereby the catalysts are partially or completely deactivated by gases containing sulfides, halides, and silicones [15]. ...
... With less than 10 seconds, the response time of catalytic bead sensors is relatively short [15]. The average lifetime of these sensors is commonly 5 years [16], which can be significantly reduced by catalyst poisoning, whereby the catalysts are partially or completely deactivated by gases containing sulfides, halides, and silicones [15]. A disadvantage is their low sensitivity in the percentage range, since relatively high gas concentrations are necessary for a sufficiently high heat release. ...
Chapter
Full-text available
Chemical, analytical and biological laboratories use a variety of different solvents and gases. Many of these compounds are harmful or even toxic to laboratory personnel. Permanent monitoring of the air quality is therefore of great importance regarding the greatest possible occupational safety and the detection of dangerous situations in the work process. An increasing need exists for the development and application of small and portable sensor solutions that enable personal monitoring and that can be flexibly adapted to different environments and situations. Different sensor principles are available for the detection of gases and solvent vapors, which differ in terms of their selectivity and sensitivity. Besides simple sensing elements, integrated sensors and smart sensors are increasingly available, which, depending on their scope of functions, require a distinct effort in integration. This chapter gives an overview of available sensors and their integration options, and describes ready-to-use sensor systems for personal monitoring in life science laboratories.
... An increasing number of evaluations of MCS and LCS as well as of networks based on such sensors are being performed, and conclusions are available from these studies such as Thompson (2016), Morawska et al. (2018), and Karagulian et al. (2019). It is well-known that these sensors suffer from drift and ageing (Brattich et al., 2020). ...
... Applications of LCS as well as networks based on such sensors have increased over the past decade (e.g. Thompson, 2016;Karagulian et al., 2019;Barmpas et al., 2020;Schäfer et al., 2021). These applications have also highlighted the need for proper evaluation, quality control, and calibration of these sensors. ...
Article
Full-text available
This review provides a community's perspective on air quality research focusing mainly on developments over the past decade. The article provides perspectives on current and future challenges as well as research needs for selected key topics. While this paper is not an exhaustive review of all research areas in the field of air quality, we have selected key topics that we feel are important from air quality research and policy perspectives. After providing a short historical overview, this review focuses on improvements in characterizing sources and emissions of air pollution, new air quality observations and instrumentation, advances in air quality prediction and forecasting, understanding interactions of air quality with meteorology and climate, exposure and health assessment, and air quality management and policy. In conducting the review, specific objectives were (i) to address current developments that push the boundaries of air quality research forward, (ii) to highlight the emerging prominent gaps of knowledge in air quality research, and (iii) to make recommendations to guide the direction for future research within the wider community. This review also identifies areas of particular importance for air quality policy. The original concept of this review was borne at the International Conference on Air Quality 2020 (held online due to the COVID 19 restrictions during 18–26 May 2020), but the article incorporates a wider landscape of research literature within the field of air quality science. On air pollution emissions the review highlights, in particular, the need to reduce uncertainties in emissions from diffuse sources, particulate matter chemical components, shipping emissions, and the importance of considering both indoor and outdoor sources. There is a growing need to have integrated air pollution and related observations from both ground-based and remote sensing instruments, including in particular those on satellites. The research should also capitalize on the growing area of low-cost sensors, while ensuring a quality of the measurements which are regulated by guidelines. Connecting various physical scales in air quality modelling is still a continual issue, with cities being affected by air pollution gradients at local scales and by long-range transport. At the same time, one should allow for the impacts from climate change on a longer timescale. Earth system modelling offers considerable potential by providing a consistent framework for treating scales and processes, especially where there are significant feedbacks, such as those related to aerosols, chemistry, and meteorology. Assessment of exposure to air pollution should consider the impacts of both indoor and outdoor emissions, as well as application of more sophisticated, dynamic modelling approaches to predict concentrations of air pollutants in both environments. With particulate matter being one of the most important pollutants for health, research is indicating the urgent need to understand, in particular, the role of particle number and chemical components in terms of health impact, which in turn requires improved emission inventories and models for predicting high-resolution distributions of these metrics over cities. The review also examines how air pollution management needs to adapt to the above-mentioned new challenges and briefly considers the implications from the COVID-19 pandemic for air quality. Finally, we provide recommendations for air quality research and support for policy.
... A combination of low humidity and high temperature is particularly problematic to EC sensors, as it can dry out the sensor's electrolyte and break the sensor. Another drawback with EC sensors is that other gases may interfere with the measurements, even though they are less sensitive than MOS sensors [52]. ...
... Disadvantages: They have high detection limits, i.e., cannot measure small pollutant concentrations, and they are susceptible to spectral interference from different gases as well as water [52]. NDIR sensors are also subject to drift [51] and they cost considerably more than MOS or EC sensors (up to a 10-fold increase in price). ...
Article
Full-text available
The significance of air pollution and the problems associated with it are fueling deployments of air quality monitoring stations worldwide. The most common approach for air quality monitoring is to rely on environmental monitoring stations, which unfortunately are very expensive both to acquire and to maintain. Hence, environmental monitoring stations are typically sparsely deployed, resulting in limited spatial resolution for measurements. Recently, low-cost air quality sensors have emerged as an alternative that can improve the granularity of monitoring. The use of low-cost air quality sensors, however, presents several challenges: They suffer from cross-sensitivities between different ambient pollutants; they can be affected by external factors, such as traffic, weather changes, and human behavior; and their accuracy degrades over time. Periodic re-calibration can improve the accuracy of low-cost sensors, particularly with machine-learning-based calibration, which has shown great promise due to its capability to calibrate sensors in-field. In this article, we survey the rapidly growing research landscape of low-cost sensor technologies for air quality monitoring and their calibration using machine learning techniques. We also identify open research challenges and present directions for future research.
... Rather, they depend on smartphone applications or other mobile devices (e.g., external battery packs) to view and store air pollution data and collect GPS data (extracted from users' phones). However, such a design often poses usability issues, causing a significant burden on participants and failing to engage citizens effectively, elicit improved environmental literacy, and harvest high-quality data [15][16][17][18]22,23]. ...
... Many portable air monitors that are commercially available and widely used, such as Air-Beam2 (HabitatMap, Brooklyn, NY, USA), Atmotube (Atmotech Inc., San Francisco, CA, USA), or Aeroqual (Aeroqual Limited, Auckland, New Zealand), claim to be an ideal tool for citizen science research. However, numerous community-based projects have faced significant challenges when implementing these devices on a wide scale [15][16][17][18]22,23]. Many existing devices require users to keep the sensor device and their smartphone at a distance of less than 10 m apart to maintain a constant Bluetooth connection between the two devices for viewing or storing data. ...
Article
Full-text available
The rapid evolution of air sensor technologies has offered enormous opportunities for community-engaged research by enabling citizens to monitor the air quality at any time and location. However, many low-cost portable sensors do not provide sufficient accuracy or are designed only for technically capable individuals by requiring pairing with smartphone applications or other devices to view/store air quality data and collect location data. This paper describes important design considerations for portable devices to ensure effective citizen engagement and reliable data collection for the geospatial analysis of personal exposure. It proposes a new, standalone, portable air monitor, GeoAir, which integrates a particulate matter (PM) sensor, volatile organic compound (VOC) sensor, humidity and temperature sensor, LTE-M and GPS module, Wi-Fi, long-lasting battery , and display screen. The preliminary laboratory test results demonstrate that the PM sensor shows strong performance when compared to a reference instrument. The VOC sensor presents reasonable accuracy, while further assessments with other types of VOC are needed. The field deployment and geo-visualization of the field data illustrate that GeoAir collects fine-grained, georef-erenced air pollution data. GeoAir can be used by all citizens regardless of their technical proficiency and is widely applicable in many fields, including environmental justice and health disparity research .
... Additionally, more and more companies provide their own LCAQS products. The principles of operation for the low-cost gas-phase sensors are typically based on five major components, which are OPC, MOS, EC, NDIR, and PID [86,87]. Studies have shown that modern LCAQS provide useful qualitative information for scientific research, as well as for end-users [85,88,89]. ...
... Studies have shown that modern LCAQS provide useful qualitative information for scientific research, as well as for end-users [85,88,89]. However, due to the embedded technical uncertainties and lack of cross-validation and verification, there are certain limitations when comparing them to the expensive conventional equipment [87,[90][91][92]. The US EPA has colloquially identified such devices to be low cost when their costs are less than US $2500, because this is often the limit when they are considered for capital investment by scientists and end-users [83]. ...
Article
Full-text available
The existence of indoor air pollutants—such as ozone, carbon monoxide, carbon dioxide, sulfur dioxide, nitrogen dioxide, particulate matter, and total volatile organic compounds—is evidently a critical issue for human health. Over the past decade, various international agencies have continually refined and updated the quantitative air quality guidelines and standards in order to meet the requirements for indoor air quality management. This paper first provides a systematic review of the existing air quality guidelines and standards implemented by different agencies, which include the Ambient Air Quality Standards (NAAQS); the World Health Organization (WHO); the Occupational Safety and Health Administration (OSHA); the American Conference of Governmental Industrial Hygienists (ACGIH); the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE); the National Institute for Occupational Safety and Health (NIOSH); and the California ambient air quality standards (CAAQS). It then adds to this by providing a state-of-art review of the existing low-cost air quality sensor (LCAQS) technologies, and analyzes the corresponding specifications, such as the typical detection range, measurement tolerance or repeatability, data resolution, response time, supply current, and market price. Finally, it briefly reviews a sequence (array) of field measurement studies, which focuses on the technical measurement characteristics and their data analysis approaches.
... Start-up companies are in urge to develop wearable inexpensive sensors to tackle the problem. A list of inexpensive and accessible sensors that measures personal air pollution exposure has mentioned in [43] [44]. The personal air sensor monitors that can easily worn and can connect to smart phone via Bluetooth include . ...
... Deterministic, physical, chemical transponders [34], [35], [36], [37], [38], [39], [40] Satellite Remote Sensing Aerosol optical depth satellite monitors, chemical transport, ground based monitoring [41], [42], [43], [44] [49], [50], [51] Retrospective method Questionnaires and Diaries, statistically group as high, medium, and low exposure ...
Article
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Indignation from air pollution is an early signal to instinctive health issues in human. Assessment of human exposure to pollutants for the epidemiological studies will be one of the subsidiary objectives of data analytics for precision medicine forecast for the individuals in the industrially polluted region. The objective of the research determines whether to estimate personal air pollution exposure or population exposure. The exposure can be long term and short term. It includes indoor and outdoor. Direct methods like personal monitoring by using smart phones, air pollution sensors are accurate but quite expensive for huge populations. Indirect methods incorporate information gained from questionnaires accompanied by measured pollutants from the monitoring sites. Lean on the nature of analysis, the assessment pattern may vary. This paper discusses most popular air pollution assessment methods applied in the epidemiological studies related to air pollution. Recent trends in epidemiological studies led to the development of air pollution exposure assessment models that rely on satellite measurement of pollutants. Usage of geographic information system for exposure assessment demands spatial analysis. Mobile applications and sensor technology equipment for personal exposure assessment are promising methods in this study. The articles discussed in this study also observes the method of measurement of each pollutant exposure to individuals by geocoding the addresses with the average pollutant concentration measured at fixed site stations.
... The development of low-cost chemical and physical sensors for air quality monitoring has been pursued using a variety of approaches [10][11][12]. Solid-state sensors can be classified as metal oxide (MOX) semiconductors (e.g., Aeroqual Air Quality Devices) and amperometric sensors [13]. The interactions with the analyte lead to changes in the device's electrical conductivity or output current. ...
... Additionally, these sensors are easily attached to electronic devices to store and transmit the obtained data. In this sense, many recently published papers have proposed deploying solid-state sensors to build an automated air quality network [11,[15][16][17]. The main drawbacks of MOX sensors rely on the operating temperature (usually higher than 200 • C), the time required to achieve signal stability, the influence of relative humidity variations, and the lack of calibrations [14]. ...
Article
Full-text available
Air quality monitoring networks are challenging to implement due to the bulkiness and high prices of the standard instruments and the low accuracy of most of the described low-cost approaches. This paper presents a low-cost, automated, self-powered analytical platform to determine the hourly levels of O3 and NO2 in urban atmospheres. Atmospheric air was sampled at a constant airflow of 100 mL min−1 directly into vials containing 800 µL of indigotris sulfonate and the Griess–Saltzman reagent solutions for ozone and nitrogen dioxide, respectively. The analysis holder, containing a light-emitting diode and a digital light sensor, enabled the acquisition of the analytical signal on-site and immediately after the sampling time. The data were transmitted to a laptop via Bluetooth, rendering remote hourly monitoring. The platform was automated using two Arduino Uno boards and fed with a portable battery recharged with a solar panel. The method provided a limit of detection of 5 and 1 ppbv for O3 and NO2, respectively, which is below the maximum limit established by worldwide regulatory agencies. The platform was employed to determine the levels of both pollutants in the atmosphere of two Brazilian cities, in which one of them was equipped with an official air quality monitoring station. Comparing the results of both techniques revealed suitable accuracy for the proposed analytical platform. Information technology (IT) allied to reliable chemical methods demonstrated high potential to create air quality monitoring networks providing valuable information on pollutants’ emissions and ensuring safety to the population.
... The EU Water Framework Directive, for example, requires member states to measure river water quality four times per year, but summed annual loadings are almost certainly underestimates with wide margins of error (Skarbøvik et al., 2012). Public health concerns are promoting investment in air quality monitoring networks in some regions (Environmental Defense Fund, 2018; United Nations Environment Programme, 2020) but networks of high-cost fixed sensors may lack the granularity to pinpoint emission hotspots or their sources, assess the influence of localised meteorology or track pollution plumes (Castell et al., 2017;Morawska et al., 2018;Rai et al., 2017;Thompson, 2016). Though modelling can go some way to filling the void, models such as atmospheric dispersion models are computationally heavy and limited in their predictive capabilities (Kumar et al., 2015). ...
Article
Full-text available
Repeat observations underpin our understanding of environmental processes, but financial constraints often limit scientists’ ability to deploy dense networks of conventional commercial instrumentation. Rapid growth in the Internet-Of-Things (IoT) and the maker movement is paving the way for low-cost electronic sensors to transform global environmental monitoring. Accessible and inexpensive sensor construction is also fostering exciting opportunities for citizen science and participatory research. Drawing on 6 years of developmental work with Arduino-based open-source hardware and software, extensive laboratory and field testing, and incorporation of such technology into active research programmes, we outline a series of successes, failures and lessons learned in designing and deploying environmental sensors. Six case studies are presented: a water table depth probe, air and water quality sensors, multi-parameter weather stations, a time-sequencing lake sediment trap, and a sonic anemometer for monitoring sand transport. Schematics, code and purchasing guidance to reproduce our sensors are described in the paper, with detailed build instructions hosted on our King’s College London Geography Environmental Sensors Github repository and the FreeStation project website. We show in each case study that manual design and construction can produce research-grade scientific instrumentation (mean bias error for calibrated sensors –0.04 to 23%) for a fraction of the conventional cost, provided rigorous, sensor-specific calibration and field testing is conducted. In sharing our collective experiences with build-it-yourself environmental monitoring, we intend for this paper to act as a catalyst for physical geographers and the wider environmental science community to begin incorporating low-cost sensor development into their research activities. The capacity to deploy denser sensor networks should ultimately lead to superior environmental monitoring at the local to global scales.
... To monitor air pollution at the personal and local level, citizens can use a mobile app to see current and predicted air quality conditions. Citizens can also carry a portable sensor device [12], allowing for a much more accurate picture of their personal exposure to pollutants. These portable sensor devices include meteorological variables such as temperature, relative humidity (percent) and wind speed, and air pollutants such as particulate matter (PM 2.5 and PM 10 ), and gases (NO 2 , CO and O 3 ). ...
Conference Paper
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Air pollution is a contributor to approximately one in every nine deaths annually. To counteract health issues resulting from air pollution, air quality monitoring is being carried out extensively in urban environments. Currently, however, city air quality monitoring stations are expensive to maintain, resulting in sparse coverage. In this paper, we introduce the design and development of the MegaSense Cyber-Physical System (CPS) for spatially distributed IoT-based monitoring of urban air quality. MegaSense is able to produce aggregated, privacy-aware maps and history graphs of collected pollution data. It provides a feedback loop in the form of personal outdoor and indoor air pollution exposure information, allowing citizens to take measures to avoid future exposure. We present a battery-powered, portable low-cost air quality sensor design for sampling PM 2.5 and air pollutant gases in different micro-environments. We validate the approach with a use case in Helsinki, deploying MegaSense with citizens carrying low-maintenance portable sensors, and using smart phone exposure apps. We demonstrate daily air pollution exposure profiles and the air pollution hot-spot profile of a district. Our contributions have applications in policy intervention management mechanisms and design of clean air routing and healthier navigation applications to reduce pollution exposure.
... The main advantage of electrochemical sensors lies in the simple portability and low price, which contributes to the ability to easily monitor selected gases within the different platforms, such as "Smart-cities" [5,6,7]. Development of low-cost, portable, and low-power devices for monitoring airborne pollutants is a crucial step towards developing improved air quality models and better quantitating the health effects of human and animal exposure [8,9,10]. ...
Article
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The paper presents the designed system to measurements of gas sensor transient characteristics. Electrochemical oxygen sensor SK-25F was selected for measurements from point of view application in health care and ensuring human safety in industrial production facilities and laboratories. The aim of this work is to design an automatic system for measuring the transient function G(s) of electrochemical sensors and to identify the mathematic model from a sample of sensors. The automatic measurement system based on a microcontroller for the measurements of dynamical characteristics of gas sensors was designed and developed. The result is transfer function with fit to estimation data higher as 99.48 %. The bandwidth of gas sensors was calculated on average at 0.0285763 Hz with a maximum deviation of 0.34 %. Finally, an algorithm for detecting the exceeding of the frequency range of an electrochemical gas sensor is proposed. Its application is in speed control UAV with the aim of accurate measurements of gases in the air by electrochemical sensors.
... For instance, it has been shown that implementing a wireless network of low-cost sensors can increase the spatial distribution and coverage area of the monitoring systems, especially if mounted on mobile platforms [2], [3]. In fact, the use of low-cost sensors aims to complement the readings from the Monitoring Stations and provide useful information about AQ at specific locations [4], [5]. ...
... [62] All these micrometeorological systems are mounted with analyzers based on optical techniques for the continuous monitorisation of the GHG. [124] Gases such as CO 2 , CH 4 , N 2 O and NH 3 have all been measured via this technique. [125,126] The major advantage of optical techniques over chromatographic ones is their ability to carry out continuous measurements, besides a robust physical basis for calibration. ...
Article
The global emission and accumulation of gases due to livestock farming is estimated to contribute to about 14.5% of the global warming effect due to greenhouse gases (GHG). Pig farming represents 9% of global livestock GHG emissions, without considering other activities of pork production process, such as feed production. Most of information about pig farms GHG emissions is based on theoretical calculations with not too much accuracy. Hence, there is a critical need to study the best sampling and analytical techniques (portable or not) that can be used to map their contribution to GHG emissions. The selection of the best analytical detection method becomes important for public policies on climate change, and in order to evaluate animal and manure handling practices to reduce GHG and to combat global warming. In this article, different techniques, which could be used to measure the emissions of GHG from livestock, are reviewed, showing the advantages and disadvantages of each technique, with special emphasis on those already used in studies about GHG from pig farms and those that allow the simultaneous determination of several species of gases. Open chambers equipped with photoacoustic multi-gas monitor have been the techniques most employed in intensive pig farms studies. Gas Chromatography coupled to different detectors has been only widely used in pig farms to monitor simultaneously several GHG species using previous sampling devices. However, there are no studies in the literature based on extensive pig farms. In these systems, micrometeorological techniques could be a promising strategy.
... biodiversity and environmental phenomena or conditions using image acquisition, web-and smartphone-based applications and surveys (Couvet and Prevot 2015;Havlik and Schimak 2014;Wallace, Snedigar, and Cameron 2015). More and more CS projects also explore the use of low-cost devices, including handheld or portable sensor systems Thompson 2016;Uhrner et al. 2014). Data collected are increasingly visualized in web-based portals or via smart phone apps in near real time. ...
Article
Full-text available
Citizen Science (CS) projects vary greatly. The aims and goals of a CS project determine the type of citizen involvement and the tools to be used, which in most cases also entail information and communication technology (ICT) that facilitates public participation in scientific research. Resource limitations in CS projects often require adopting suboptimal tools, which, however, may come with hidden costs stemming from poor usability and underwhelming functionality, thus reducing volunteers’ motivation. Meeting the volunteers’ expectations by designing or using existing tools with functional features which fulfill and nurture their motivations, will foster long-term participation and contribute to project sustainability. This paper reviews the types of CS projects, volunteer motivation and retention strategies from the literature and classifies them thematically. This is distilled into guidance that can help CS practitioners to design and implement CS tools and plan and manage CS projects, which better serve their scientific and volunteer-related goals.
... These networked sensors open tremendous opportunities for decentralized data generation, structured and unstructured data visualization, and transcription of data to information that can be utilized to inform the status of the problem, monitor the effectiveness of mitigation strategies, and inform the decision making by, for example, farmers and the general public. These platforms are lately called 'uber' sensors, for artificial intelligence, or more synonymously called the Internet of Things (IoT) or Internet of Everything (IoE) (Shi et al. 2019b;Yang et al. 2018;Thompson 2016). These devices are drivers in the digital era, the essential features of disruptive technology, which is influencing the massive change in the world while extending the limits of what is technically possible. ...
Chapter
This concluding chapter not only acknowledges that, across Africa, glimpses of the development and use of disruptive innovations are everywhere. It submits that Africa’s reality goes against the often made assumption that the continent’s contribution to digitization, AI and IoT is minimal. More importantly, it argues that Africa has grasped the promise of the 4IR, being home to over 400 tech hubs, with many “disruptions” happening locally as the unique challenges faced continue to give rise to new and innovative ideas or solutions, attracting foreign investors in numbers unimaginable in just a few years. However, since disruptive technologies offer benefits and drawbacks, the challenge is the ability or flexibility required to manage such technologies and reshape changes. To this end, the chapter affirms the centrality of education, capacity building, transformative leadership, increased investment in telecommunications, and a need to have the requisite infrastructure and related industries in place for the desired benefits of disruptive technologies to be fully realized.
... With the development of mobile-internet technology and portable PM 2.5 monitors, a new type of method based on crowdsourcing observations has emerged in recent years (Al-Ali et al., 2010). For this method type, extremely large data sets are collected by people or vehicles moving around a city to more accurately capture PM 2.5 distributions (Thompson, 2016). This method may be one of the most promising solutions to capture the PM 2.5 variations at a higher spatio-temporal resolution in intraurban areas (Pan, 2016). ...
... With the availability of integrated low-cost air environment monitoring solutions, it is clear that the technology for real-time citizen sensing is advancing rapidly. However, such solutions have some major limitations, including project setup, validation [39], data reliability [40], security [16] and accessible tools for data analysis. AirKit aims to create an accurate, open and reliable air quality monitoring system, while investigating the role of low-cost sensors and digital monitoring technologies in facilitating and organising new types of environmental engagement. ...
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Increasing urbanisation and a better understanding of the negative health effects of air pollution have accelerated the use of Internet of Things (IoT)-based air quality sensors. Low-cost and low-power sensors are now readily available and commonly deployed by individuals and community groups. However, there are a wide range of such IoT devices in circulation that differently focus on problems of sensor validation, data reliability, or accessibility. In this paper, we present AirKit, which was developed as an integrated and open source “social IoT technology.” AirKit enables a comprehensive approach to citizen-sensing air quality through several integrated components: (1) the Dustbox 2.0, a particulate matter sensor; (2) Airsift, a data analysis platform; (3) a reliable and automatic remote firmware update system; (4) a “Data Stories” method and tool for communicating citizen data; and (5) an AirKit logbook that provides a guide for designing and running air quality projects, along with instructions for building and using AirKit components. Developed as a social technology toolkit to foster open processes of research co-creation and environmental action, Airkit has the potential to generate expanded engagements with IoT and air quality by improving the accuracy, legibility and use of sensors, data analysis and data communication.
... While the implementation of portable sensing techniques is promising, researchers should keep in mind the current limitations of these techniques. One of the main limitations is their inferior quality (Thompson, 2016). Compared to static sensors (e.g., those installed at environmental monitoring stations), portable sensors tend to be less accurate and reliable due to technological constraints posed by their size and limited power availability (i.e., they are often dependent on battery power). ...
Article
Portable sensing, in which lightweight mobile sensors are used to measure stimuli, events, and human behavior, is a new and disruptive data collection paradigm. It has several methodological advantages compared to traditional methods and is suitable for investigating the dynamism of increasingly mobile and urban societies. In this article, we discuss the motivations behind the use of portable sensing and reflect upon the advances, limitations, and future of the field. Although portable sensing is still in its infancy, we foresee that its utilization will grow in the coming years. For portable sensing to become a prevalent and legitimate methodological approach, it is essential to have conceptually strong study designs that are grounded in suitable ethical procedures and comply with data protection regulations.
... The appearance of these inexpensive sensors has resulted in a change in the monitoring paradigm, with a shift from the current governmental model towards the establishment of community-based monitoring networks (Snyder et al. 2013;Rai et al. 2017;Morawska et al. 2018). The ease with which citizens can acquire air quality monitors has led to the development of multiple crowdsourced projects that aim to increase the density of monitoring networks in regions that currently lack air quality monitoring equipment (Thompson, 2016;Castell et al. 2017;Chen et al. 2017). ...
Article
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Integration of low-cost air quality sensors with the internet of things (IoT) has become a feasible approach towards the development of smart cities. Several studies have assessed the performance of low-cost air quality sensors by comparing their measurements with reference instruments. We examined the performance of a low-cost IoT particulate matter (PM10 and PM2.5) sensor in the urban environment of Santiago, Chile. The prototype was assembled from a PM10–PM2.5 sensor (SDS011), a temperature and relative humidity sensor (BME280) and an IoT board (ESP8266/Node MCU). Field tests were conducted at three regulatory monitoring stations during the 2018 austral winter and spring seasons. The sensors at each site were operated in parallel with continuous reference air quality monitors (BAM 1020 and TEOM 1400) and a filter-based sampler (Partisol 2000i). Variability between sensor units (n = 7) and the correlation between the sensor and reference instruments were examined. Moderate inter-unit variability was observed between sensors for PM2.5 (normalized root-mean-square error 9–24%) and PM10 (10–37%). The correlations between the 1-h average concentrations reported by the sensors and continuous monitors were higher for PM2.5 (R2 0.47–0.86) than PM10 (0.24–0.56). The correlations (R2) between the 24-h PM2.5 averages from the sensors and reference instruments were 0.63–0.87 for continuous monitoring and 0.69–0.93 for filter-based samplers. Correlation analysis revealed that sensors tended to overestimate PM concentrations in high relative humidity (RH > 75%) and underestimate when RH was below 50%. Overall, the prototype evaluated exhibited adequate performance and may be potentially suitable for monitoring daily PM2.5 averages after correcting for RH.
... Thus, comprehensive studies on air quality are vital to understanding the problems associated with it. Previous reviews have clearly highlighted a relationship between a realistic air quality measure and the sensor quality, mode of transport, local exposure, and big data analysis (Cepeda et al. 2017;Commodore et al. 2017;Thompson 2016). Nevertheless, the rapid development of sensors for mobile devices and epidemiological studies based on crowdsensing data make necessary a summary concerning all the recent advances. ...
Article
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The spatiotemporal heterogeneity of the air pollutants complicates appropriate monitoring. The collective measures or crowdsensing is a promising approach to achieve a better air pollution assessment because it includes the local concentration of pollutants, as well as the position and mobility of people. Thus, compared to traditional static monitoring, the participatory sensing data by low-cost sensors can avoid the misclassification of exposition to air pollutants, enabling a comprehensive understanding of their health effects. This systematic review integrates each core part of what is required to achieve crowdsensing for air pollution: sensors, portable devices, and data models. Despite the limitations of sensors in terms of sensitivity and selectivity, it has been possible to use portable air monitors to determine pollution hotspots around the world. However, limited models for data processing, performance issues when using low-cost devices, in addition to lack of community engagement, are the challenges to overcome for the feasibility of air pollution assessment with portable monitors. Graphical abstract
... At present, gas sensors are usually assigned to monitor a large number of poisonous and harmful gases in the environment and industries [21]. And also these are used in food quality assessment [22], air quality monitoring [23]. in more response, which results low detection limit and (d) are often more thermally and chemically stable [2][3][4][5][6] MOFs gained the huge interest among the researchers for the development of a selective and sensitive sensor for detection of a gas. ...
Preprint
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In the present work, we fabricated 1:1 bimetallic ZnCu(NA); ZnCd(NA); and ZnCo(NA) metal organic frameworks (MOFs) using nicotinic acid (NA) as organic linker by solvothermal method. Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) analysis, X-Ray Photoelectron Spectroscopy (XPS), and scanning electron microscopy (SEM) were used to describe all bimetallic MOF topologies. These compounds were used to develop chemiresistive sensor devices for sensing of formaldehyde vapor at room temperature. Drop-casting method was used to make the sensing device on a glass plate with silver electodes. The resulting bimetallic sensors exhibited excellent sensitivity, good linearity and more stability in the detection of formaldehyde at 1 to 50 ppm concentrations. ZnCo(NA) exhibited more response towards formaldehyde vapor than other bimetallic MOFs. Transient response analysis was used to determine response and recovery times, as well as stability over time. These findings prove the application prospects of bimetallic Zn/Cu, Zn/Cd and Zn/Co MOFs in the selective and sensitive detection of formaldehyde at room temperature.
... As a result, the number of projects dealing with participatory sensing in urban air pollution has increased significantly in recent years. Some of the most notable projects are CitiSense (Zappi et al. 2012), Common Sense and CamMobSens (Thompson 2016), and EQUATOR's e-science and AirU (Steed et al. 2003). However, to date, little social science research has been conducted to explore how individuals use sensors and sensor data or how sensor data influence individuals' attitudes and behavioral intentions regarding air pollution (Hubbell et al. 2018). ...
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In southern Chile, epidemiological studies have linked high levels of air pollution produced by the use of wood-burning stoves with the incidence of numerous diseases. Using a quasi-experimental design, this study explores the potential of participatory sensing strategies to transform experiences, perceptions, attitudes, and daily routine activities in 15 households equipped with wood-burning stoves in the city of Temuco, Chile. The results suggest that the experience of using a low-cost sensor improves household members’ awareness levels of air pollution. However, the information provided by the sensors does not seem to improve the participants’ self-efficacy to control air quality and protect themselves from pollution. The high degree of involvement with the participatory sensing experience indicates that the distribution of low-cost sensors could be a key element in the risk communication policies.
... Low maintenance requirements and ease/affordability of replacing damaged sensors make CGS ideal for these networks which can help to supplement sparse, pre-existing air pollution networks [12,13]. Furthermore, the cost barrier to work with CGS is significantly lower which opens up possibilities for community-driven science [14,15]. ...
Article
Indoor Air Quality (IAQ) monitoring is essential to assess occupant exposure to the wide range of pollutants present in indoor environments. Accurate research-grade monitors are often used to monitor IAQ but the expense and logistics associated with these devices often limits the temporal and spatial scale of monitoring efforts. More affordable consumer-grade sensors – frequently referred to as low-cost sensors – can provide insight into IAQ conditions across greater scales but their accuracy and calibration requirements need further evaluation. In this paper, we present the Building EnVironment and Occupancy (BEVO) Beacon. The BEVO Beacon is entirely open-source, including the software, hardware, and design schematics which are all provided on GitHub. We created 20 of these standalone, stationary devices which measure up to 24 parameters at a one-minute resolution of which we focus on carbon dioxide, carbon monoxide, total volatile organic compounds, temperature, and size-resolved particulate matter. We investigated the efficacy of two different calibration approaches – device-specific and environment-averaged – for these sensors as well as also provide an extensive discussion considerations for each of the sensors. Calibrated sensors performed well when compared to reference monitors or calibrated gas standards. The CO sensors yielded the best agreement (r2=0.98-0.99), followed by temperature (r2=0.89-0.99), CO (r2=0.62-0.99), and PM2.5 (r2=-0.13-0.91). In all cases, the device-specific calibration approach yielded the most accurate results. We evaluated our devices through a successful 11-week field study where we monitored the IAQ in participants’ bedrooms. The work we present on consumer-grade sensors adds to the existing literature by considering sensor-specific calibration techniques and analysis. The BEVO Beacon adds to the successful line of similarly developed devices by providing an open-source framework that researchers can readily adapt and modify to their own applications.
... It can provide high-precision spatial measurements. The use of low-cost devices should be associated with field calibration to ensure reliable results, and calibration is performed using reference devices [15][16][17]. ...
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Few air pollution studies have been applied in the State of Palestine and all showed an increase in particulate matter concentrations above WHO guidelines. However, there is no clear methodology for selecting monitoring locations. In this study, a methodology based on GIS and locally calibrated low-cost sensors was tested. A GIS-based weighted overlay summation process for the potential sources of air pollution (factories, quarries, and traffic), taking into account the influence of altitude and climate, was used to obtain an air pollution hazard map for Nablus, Palestine. To test the methodology, eight locally calibrated PM sensors (AirUs) were deployed to measure PM2.5 concentrations for 55 days from 7 January to 2 March 2022. The results of the hazard map showed that 82% of Nablus is exposed to a high and medium risk of PM pollution. Sensors’ readings showed a good match between the hazard intensity and PM concentrations. It also shows an elevated PM2.5 concentrations above WHO guidelines in all areas. In summary, the overall average for PM2.5 in the Nablus was 48 µg/m3. This may indicate the effectiveness of mapping methodology and the use of low-cost, locally calibrated sensors in characterizing air quality status to identify the potential remediation options.
... It can provide high-precision spatial measurements. The use of low-cost devices should be associated with field calibration to ensure reliable results, and calibration is performed using reference devices [15][16][17]. ...
Article
Full-text available
Few air pollution studies have been applied in the State of Palestine and all showed an increase in particulate matter concentrations above WHO guidelines. However, there is no clear methodology for selecting monitoring locations. In this study, a methodology based on GIS and locally calibrated low-cost sensors was tested. A GIS-based weighted overlay summation process for the potential sources of air pollution (factories, quarries, and traffic), taking into account the influence of altitude and climate, was used to obtain an air pollution hazard map for Nablus, Palestine. To test the methodology, eight locally calibrated PM sensors (AirUs) were deployed to measure PM2.5 concentrations for 55 days from 7 January to 2 March 2022. The results of the hazard map showed that 82% of Nablus is exposed to a high and medium risk of PM pollution. Sensors’ readings showed a good match between the hazard intensity and PM concentrations. It also shows an elevated PM2.5 concentrations above WHO guidelines in all areas. In summary, the overall average for PM2.5 in the Nablus was 48 µg/m3. This may indicate the effectiveness of mapping methodology and the use of low-cost, locally calibrated sensors in characterizing air quality status to identify the potential remediation options.
... Generally, the term LCS implies inexpensive sensor nodes costing less than 100 US dollars (Chojer et al., 2020;Morawska et al., 2018;Rai et al., 2017). LCS are a portable, user-friendly and economical solution that can provide near real-time air quality analysis while offering scalability and widespread availability (Castell et al., 2013;Thompson, 2016;White et al., 2012). They spearhead the paradigm shift in air quality monitoring Snyder et al. (2013) by being a potential supplement to the enormous, expensive traditional monitoring methods by implementing relatively cheaper technologies such as electrochemical cell (EC), metal oxide semiconductor (MOS), nondispersive infrared (NDIR), nephelometry, and optical particle counters (OPC) among others (Hagan and Kroll, 2020;White et al., 2012). ...
Article
Poor indoor air quality has adverse health impacts. Children are considered a risk group, and they spend a significant time indoors at home and in schools. Air quality monitoring has traditionally been limited due to the cost and size of the monitoring stations. Recent advancements in low-cost sensors technology allow for economical, scalable and real-time monitoring, which is especially helpful in monitoring air quality in indoor environments, as they are prone to sudden peaks in pollutant concentrations. However, data reliability is still a considerable challenge to overcome in low-cost sensors technology. Thus, following a monitoring campaign in a nursery and primary school in Porto urban area, the present study analyzed the performance of three commercially available low-cost IoT devices for indoor air quality monitoring in real-world against a research-grade device used as a reference and developed regression models to improve their reliability. This paper also presents the developed on-field calibration models via machine learning technique using multiple linear regression, support vector regression, and gradient boosting regression algorithms and focuses on particulate matter (PM1, PM2.5, PM10) data collected by the devices. The performance evaluation results showed poor detection of particulates in classrooms by the low-cost devices compared to the reference. The on-field calibration algorithms showed a considerable improvement in all three devices' accuracy (reaching up to R² > 0.9) for the light scattering technology based particulate matter sensors. The results also show the different performance of low-cost devices in the lunchroom compared to the classrooms of the same school building, indicating the need for calibration in different microenvironments.
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Weather in Malaysia are hot and humid throughout the year thus having a sudden rain can disrupt the drying of laundries and make them wet. In this study, an automated retractable roof system was developed to overcome this problem. The development and implementation of this study enables user to monitor the parameters at the laundry suspension area by using their smartphone and prevent the laundries getting wet from rain. This study uses humidity sensors, Ultraviolet (UV) sensor, rain sensor, and temperature sensor to detect parameter such as humidity, UV intensity, presence of water and temperature respectively. Data from the sensors were collected and analysed to determine the values of parameters when rains occurred. These parameters were indicated as part of weather prediction study. From experiment, the retractable roof will open and close depended on condition met by the system. In addition, the system can communicate with the user’s phone through using Internet connection. The Blynk application in the smartphone allows the user to monitor and control the system through internet connection between the application and microcontroller. This study will be helpful for non-commercial use and can be expanded to commercial use as with further improvement.
Article
Metal-organic frameworks (MOFs)-- tunable, nano-porous materials-- are alluring recognition elements for gas sensing. Mimicking human olfaction, an array of cross-sensitive, MOF-based sensors could enable analyte detection in complex, variable gas mixtures containing confounding gas species. Herein, we address the question: given a set of MOF candidates and their adsorption properties, how do we select the optimal subset to compose a sensor array that accurately and robustly predicts the gas composition via monitoring the adsorbed mass in each MOF? We first mathematically formulate the MOF-based sensor array problem under dilute conditions. Instructively, the sensor array can be viewed as a linear map from gas composition space to sensor array response space defined by the matrix H of Henry coefficients of the gases in the MOFs. Characterizing this mapping, the singular value decomposition of H is a useful tool for evaluating MOF subsets for sensor arrays, as it determines the sensitivity of the predicted gas composition to measurement error, quantifies the magnitude of the response to changes in composition, and recovers which direction in gas composition space elicits the largest/smallest response. To illustrate, on the basis of experimental adsorption data, we curate MOFs for a sensor array with the objective of determining the concentration of CO2 and SO2 in the gas phase.
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In Delhi, the capital city of India, air pollution has been a perpetual menace to urban sustainability and public health. The present study uses a mixed-method approach to enumerate to the urban authorities: (a) the state of air pollution in the city; (b) systemic flaws in the current monitoring network; (c) potential means to bolster it; and (d) need of a participatory framework for monitoring. Information about Air Quality Index (AQI), obtained from 36 monitoring stations across Delhi is compared between 2021 (20 April–25 May; 2nd year/phase of SARS-CoV-2 lockdown), and the corresponding time periods in 2020 (1st year/phase of lockdown), and 2019 (business-as-usual) using the Mann–Whitney U Test. AQI during the 2021 lockdown (a) appeared statistically more similar ( p < .01) to that of 2019 and (b) exceeded the environmental health safety benchmark for 85% days during the study period (20 April–25 May). However, this only presented a partial glimpse into the air pollution status. It owes to numerous ‘holes’ in the AQI data record (no data and/or insufficient data). Moreover, certain areas in Delhi yet have no monitoring station, or only too few, to yield a ‘representative’ estimate (inadequate spatial coverage). Such shortcomings in the existing monitoring network may deter future research and targeted/informed decision-making for pollution control. To that end, the present research offers a summary view of Low-Cost Air Quality Sensors (LCAQS), to offer the urban sustainability authorities, ‘complementary’ technique to bolster and diversify the existing network. The main advantages and disadvantages of various LCAQS sensor technologies are highlighted while emphasizing on the challenges around various calibration techniques (linear and non-linear). The final section reflects on the integration of science and technology with social dimensions of air quality monitoring and highlights key requirements for (a) community mobilization and (b) stakeholder engagement to forge a participatory systems’ design for LCAQS deployment.
Article
This research aims to discuss the application of multi-sensor network technology for the monitoring of indoor air pollution. Indoor air pollution has become a severe problem that affects public health, especially indoor parking. The indoor air pollution monitoring system will provide information about vehicle exhaust emission levels. We have improved the system to identify six parameters of the vehicles' gas emissions within a different location at once. This research aimed to measure the parameter of Carbon Monoxide (CO), Carbon Dioxide (CO2), Hydro Carbon (HC), temperature and humidity, and levels of particulates in the air (PM10). The performance of this system shows good ability to compare the results of measurements of air quality measuring professionals. In this study, we investigated the performance of a custom-built prototype developed under the android-based application to detect air pollution levels in the parking area. Our objective was to evaluate the suitability of a low-cost multi-sensor network for monitoring air pollution in parking and the other area. The benefit of our approach is that its time and space complexity make it valuable and efficient for real-time monitoring of air pollution.
Thesis
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https://repository.up.ac.za/handle/2263/68673
Article
In this paper we describe our work aimed at designing a system able to measure the particulate matter (PM) concentrations via an optical particle counter (OPC) and simultaneously collect it via standard 2.5 cm filters for laboratory characterization. The Port of Civitavecchia (Italy), one of the most important maritime hubs of the Mediterranean Sea, was selected as a test site for an eight-months monitoring campaign. Comparison between the data provided by our device with those from the referenced and certified monitoring stations from the governmental Regional Agency for the Protection of the Environment (ARPA Lazio) allowed to define clear threshold values (PM10 = 25 μg/m³ and PM2.5 = 10 μg/m³). These threshold values need to be considered when correcting the OPC raw data with respect to the humidity (RH) conditions. The sample material was characterized through optical microscopy and SEM-EDS (scanning electron microscopy coupled with energy-dispersive X-ray fluorescence) and spectroscopy (FTIR, Raman), showing a variegate composition from Al-Fe-oxides to silicates, carbonates, and sulfates, to coal and amorphous carbon together with microplastics and textile fibers. As a final test, we analyzed the PM trends provided by our device during the Covid-19 lockdown, when stringent restrictions in the human activities caused well-known fluctuations in the atmospheric pollution. We again observed an evolution of the PM peaks in excellent agreement with the results yielded by the ARPA Lazio monitoring stations. This result provides a valuable confidence test for our devices highlighting the effectiveness of the presented strategy for airborne particulate-matter monitoring.
Chapter
Scientific innovations, specifically smart sensors, have significant implications for addressing environmental problems. Smart sensors are creatively addressing key global societal issues, from environmental pollution and mitigation, intelligent water and waste management, precision agriculture, public health and nutrition, food safety, to energy conservation and climate change. Smart sensors and their disruptive potential are integral to the African development agenda. This chapter will explore the trends and perspectives of integrated smart sensors in the context of disruptive technology. The chapter will also focus on the innovation tangents driven by internationalization of technology and the capacity of universities to spearhead homegrown technological solutions. Finally, the chapter will analyze how smart sensors could offer an appropriate framework in resource utilization and the management of e-waste.
Thesis
Full-text available
Few of the air pollution studies were applied in the State of Palestine, all showed an increase in particulate matter concentrations above WHO guidelines. However, there is no clear methodology for selecting monitoring locations. In this study a methodology based on GIS and locally calibrated low-cost sensors was tested. A GIS-based weighted overlay summation process for the potential sources of air pollution (factories, quarries, and traffic) taking into account the influence of altitude and climate was used to obtain a particulate matter (PM) pollution hazard map for Nablus, Palestine. To test the methodology, eight locally calibrated PM sensors (AirUs) were deployed to measure PM2.5 and PM10 concentrations for 55 days from 7-Jan to 2-Mar 2022. The results of the hazard map showed that 82% of Nablus is exposed to a very high and high hazard of PM pollution. It also shows an elevated PM2.5 concentrations above WHO guidelines in all stations. In summary, the overall average for PM2.5 and PM10 in Nablus was 48 and 55.2 µg/m3 respectively Sensors’ readings showed a good match between the hazard index and PM concentrations. This indicate the effectiveness of mapping methodology and the use of low-cost, locally calibrated sensors in characterizing air quality status to identify the potential remediation options .
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Urban environments with a high degree of industrialization are infested with hazardous chemicals and airborne pollutants. These pollutants can have devastating effects on human health, causing both acute and chronic diseases such as respiratory infections, lung cancer, and heart disease. Air pollution monitoring is vital not only to citizens, warning them on the health risks of air pollutants, but also to policy-makers, assisting them on drafting regulations and laws that aim at minimizing those health risks. Currently, air pollution monitoring predominantly relies on expensive high-end static sensor stations. These stations produce only aggregated information about air pollutants, and are unable to capture variations in individual's air pollution exposure. As an alternative, this article develops a citizen-based air pollution monitoring system that captures individual exposure levels to air pollutants during daily indoor and outdoor activities. We present a low-cost portable sensor and carry out a measurement campaign using the sensors to demonstrate the validity and benefits of citizen-based pollution measurements. Specifically, we (i) successfully classify the data into indoor and outdoor, and (ii) validate the consistency and accuracy of our outdoor-classified data to the measurements of a high-end reference monitoring station. Our experimental results further prove the effectiveness of our campaign by (i) providing fine-grained air pollution insights over a wide geographical area, (ii) identifying probable causes of air pollution dependent on the area, and (iii) providing citizens with personalized insights about air pollutants in their daily commute.
Book
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(A&EI) as a novel subfield became obvious. As in all areas of Biomedical Informatics, A&EI must deal with issues such as relevant data collection, the management of data extracted from accident sites, health records or sensors, wearables and apps, and appropriate data processing, with the dual purpose of preventing harm and decision support. This book is an introduction to the research and application domain of A&EI, and is the product of three years’ work by the Working Group in A&EI of the International Medical Informatics Association (IMIA). The book presents ten chapters organized in four sections. The first section explores the framework for achieving an emergency-informatics health information infrastructure; the second focuses on the gathering of critical clinical data related to the building up of a smart environment for A&EI; the third introduces state-of-the-art technologies for integration into virtual emergency registries; and the final part considers the delicate issues of patient safety raised by the introduction of surveillance technologies into clinical care, along with other issues presenting challenges to the domain of A&EI for the future. The book is an important contribution to the field of A&EI, and will be of interest to healthcare professionals, informaticians, and all those who want a better understanding of the domain of Accident and Emergency Informatics.
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Deteriorating levels of indoor air quality is a prominent environmental issue that results in long-lasting harmful effects on human health and wellbeing. A concurrent multi-parameter monitoring approach accounting for most crucial indoor pollutants is critical and essential. The challenges faced by existing conventional equipment in measuring multiple real-time pollutant concentrations include high cost, limited deployability, and detectability of only select pollutants. The aim of this paper is to present a comprehensive indoor air quality monitoring system using a low-cost Raspberry Pi-based air quality sensor module. The custom-built system measures 10 indoor environmental conditions including pollutants: temperature, relative humidity, Particulate Matter (PM)2.5, PM10, Nitrogen dioxide (NO2), Sulfur dioxide (SO2), Carbon monoxide (CO), Ozone (O3), Carbon dioxide (CO2), and Total Volatile Organic Compounds (TVOCs). A residential unit and an educational office building was selected and monitored over a span of seven days. The recorded mean PM2.5, and PM10 concentrations were significantly higher in the residential unit compared to the office building. The mean NO2, SO2, and TVOC concentrations were comparatively similar for both locations. Spearman rank-order analysis displayed a strong correlation between particulate matter and SO2 for both residential unit and the office building while the latter depicted strong temperature and humidity correlation with O3, SO2, PM2.5, and PM10 when compared to the former.
Chapter
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The 21st century has seen an enormous growth in emergency medical services (EMS) information technology systems, with corresponding accumulation of large volumes of data. Despite this growth, integration efforts between EMS-based systems and electronic health records, and public-sector databases have been limited due to inconsistent data structure, data missingness, and policy and regulatory obstacles. Efforts to integrate EMS systems have benefited from the evolving science of entity resolution and record linkage. In this chapter, we present the history and fundamentals of record linkage techniques, an overview of past uses of this technology in EMS, and a look into the future of record linkage techniques for integrating EMS data systems including the use of machine learning-based techniques.
Preprint
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Urban air quality is increasingly becoming a cause for concern for the health of the human population. The poor air quality is already wreaking havoc in major cities of the world, where serious health issues and reduction of average human life by a factor of years are reported. The air quality in developing countries can become worse as they undergo development. The urban air quality varies non-linearly depending upon the various factors such as land use, industrialization, waste disposal, traffic volume, etc. To address this problem, it is necessary to look at the plethora of available literature from multiple perspectives such as types and sources of pollutants, meteorology, urban mobility, urban planning and development, health care, economics, etc. In this paper, we provide a comprehensive survey of the state-of-the-art in urban air quality. We first review the fundamental background on air quality and present the emerging landscape of urban air quality. We then explore the available literature from multiple urban air quality measurement projects and provides the insights uncovered in them. We then take a look at the sources that are significantly contributing to polluting the air quality. Finally, we highlight open issues and research challenges in dealing with urban air pollution.
Preprint
Urban air quality is increasingly becoming a cause for concern for the health of the human population. The poor air quality is already wreaking havoc in major cities of the world, where serious health issues and reduction of average human life by a factor of years are reported. The air quality in developing countries can become worse as they undergo development. The urban air quality varies non-linearly depending upon the various factors such as land use, industrialization, waste disposal, traffic volume, etc. To address this problem, it is necessary to look at the plethora of available literature from multiple perspectives such as types and sources of pollutants, meteorology, urban mobility, urban planning and development, health care, economics, etc. In this paper, we provide a comprehensive survey of the state-of-the-art in urban air quality. We first review the fundamental background on air quality and present the emerging landscape of urban air quality. We then explore the available literature from multiple urban air quality measurement projects and provides the insights uncovered in them. We then take a look at the sources that are significantly contributing to polluting the air quality. Finally, we highlight open issues and research challenges in dealing with urban air pollution.
Chapter
Clinical information systems (CIS) have developed rapidly over the last 20 years and are now found in all settings that deliver and support care. From small clinics to large tertiary care settings, blood banks to pharmacies, CIS are ubiquitous. These systems may be composed of single software solutions or complex integrated modules to create a complex system. Healthcare functionality provided by software has become so broad that once simple medical devices are now minicomputers that need to be interfaced with the larger electronic health record. Telehealth allows for the provision of care outside of the physical walls of an organization, and communication between providers and patients can be accomplished today via secure messaging. Health information exchanges allow information to flow between providers and organizations. Registries take advantage of the patient data being collected to better track conditions and preventive and treatment services. As these systems have matured, the door has opened to innovations that will bring healthcare technology well beyond where it is today.KeywordsClinical information systemHospital information systemElectronic medical recordElectronic health recordTelemedicinePatient portalsHealth communicationHospital communication systemRegistriesMedical device
Chapter
Air pollution is one of the biggest contributors to the global burden of disease and mortality and contributes to over a million deaths worldwide every year. Short- and long-term exposures to air pollutants, when they are present in high concentration, lead to respiratory illnesses, aggravation of cardiovascular diseases, and premature deaths. The accurate assessment of health risk and impact due to ambient and indoor air pollution is imperative for policymaking, prevention, and rectification efforts. Technological intervention and advancement in data science and modelling predictions could be of use for accurate health risk assessment and exposure to the pollution which includes exposure to small and large populations. Internet of Things includes sensors, smartphones, and air pollution models based on big data sources which are not only used to assess the exposure, but also aid in devising prevention opportunities. Key features of these tools include accessibility, spatial resolution, specific health outcomes associated with pollutants, population exposure, and application. This chapter is a state-of-the-art review that elaborates the attempts and technological interventions and advancements made to address the health risk assessment associated with air pollution and strategies adopted for personalized treatment to avert exacerbation and refractory symptoms. Technological advancement and its involvement may revolutionize the air pollution prediction, exposure, and risk assessment research in the coming time, if they meet the logistical and data science challenges along with the integration of health impact and related risks’ assessment which is linked to the exposure of air pollution. Keywords Exposure, Health, Internet of Things, Technology, Data science
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Nitrogen species present in the atmosphere, soil, and water play a vital role in ecosystem stability. Reactive nitrogen gases are key air quality indicators and are responsible for atmospheric ozone layer depletion. Soil nitrogen species are one of the primary macronutrients for plant growth. Species of nitrogen in water are essential indicators of water quality, and they play an important role in aquatic environment monitoring. Anthropogenic activities have highly impacted the natural balance of the nitrogen species. Therefore, it is critical to monitor nitrogen concentrations in different environments continuously. Various methods have been explored to measure the concentration of nitrogen species in the air, soil, and water. Here, we review the recent advancements in optical and electrochemical sensing methods for measuring nitrogen concentration in the air, soil, and water. We have discussed the advantages and disadvantages of the existing methods and the future prospects. This will serve as a reference for researchers working with environment pollution and precision agriculture.
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Low-cost sensors (LCS) are becoming popular for air quality monitoring (AQM). They promise high spatial and temporal resolutions at low-cost. In addition, citizen science applications such as personal exposure monitoring can be implemented effortlessly. However, the reliability of the data is questionable due to various error sources involved in the LCS measurement. Furthermore, sensor performance drift over time is another issue. Hence, the adoption of LCS by regulatory agencies is still evolving. Several studies have been conducted to improve the performance of low-cost sensors. This article summarizes the existing studies on the state-of-the-art of LCS for AQM. We conceptualize a step by step procedure to establish a sustainable AQM setup with LCS that can produce reliable data. The selection of sensors, calibration and evaluation, hardware setup, evaluation metrics and inferences, and end user-specific applications are various stages in the LCS-based AQM setup we propose. We present a critical analysis at every step of the AQM setup to obtain reliable data from the low-cost measurement. Finally, we conclude this study with future scope to improve the availability of air quality data.
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Over 30 years, portable systems for fast and reliable gas analysis are at the core of both academic and industrial research. Miniaturized systems can be helpful in several domains. The way to make it possible is to miniaturize the whole gas chromatograph. Micro-system conception by etching silicon channel is well-known. The main objective is to obtain similar or superior efficiencies to those obtained from laboratory chromatographs. However, stationary phase coatings on silicon surface and micro-detector conception with a low limit of detection remain a challenge. Developments are still in progress to offer a large range of stationary phases and detectors to meet the needs of analytical scientists. This review covers the recent development of micro-gas analyzers. It focuses on injectors, stationary phases, column designs and detectors reported in the literature during the last three decades. A list of commercially available micro-systems and their performances will also be presented.
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A chromophore based on tricyanofuran (TCF) with a hydrazone (H) recognition moiety was developed. Its molecular-switching performance is reversible and has differential sensitivity towards aqueous ammonia at comparable concentrations. Nanofibers were fabricated from the TCF-H chromophore by electrospinning. The film fabricated from these nanofibers functions as a solid-state optical chemosensor for probing ammonia vapor. Recognition of ammonia vapor occurs by proton transfer from the hydrazone fragment of the chromophore to the ammonia nitrogen atom and is facilitated by the strongly electron withdrawing TCF fragment. The TCF-H chromophore was added to a solution of poly(acrylic acid), which was electrospun to obtain a nanofibrous sensor device. The morphology of the nanofibrous sensor was determined by SEM, which showed that nanofibers with a diameter range of 200-450 nm formed a nonwoven mat. The resultant nanofibrous sensor showed very good sensitivity in ammonia-vapor detection. Furthermore, very good reversibility and short response time were also observed.
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We report on a new low-cost non-dispersive infrared (NDIR) based sensor platform for sub-ppm gas detection. The aim of the sensor platform development was to create a cost-effective, mass-producible and highly accurate device. Due to its sensitivity, the platform is well suitable for measuring and detecting gases like carbon dioxide, methane, dinitrogen oxide, ammonia, ethanol vapour, refrigerants, etc. The sensor is based on the White-cell NDIR approach and realizes a path length of 1.28 m in a device with an external length of less than 10 cm. High mechanical accuracy of the optical system, temperature controlled optics, highly stable electronics and an optimized mirror surfaces allow a detection level as low as 0.007 ppm.
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A simple monitoring system of indoor air pollution is proposed by integrating a novel colorimetric detector of formaldehyde (HCHO) and a function of a built-in camera on mobile phone. The colorimetric detector employs a solid phase colorimetric reagent made from AHMT, ZnO, KIO4 and agar, and changes color from white to purple by exposure to HCHO gas. The degree of color changes expressed in RGB model responded to the HCHO concentration levels both in air and from building materials. Limit of quantitation of the detector with 24h-exposure resulted in 0.011 mg/m(3) of air concentration which meets a requirement of methodology to detect indoor air quality guideline level of HCHO set by WHO. The detector is also applicable to classify HCHO-emitting materials at least into Type 1, whose emission flux is greater than 120 μg/m(2)/h, and others. Then, variation of the acquired photo images was investigated by using various mobile phones and changing conditions of photography. As a result, the calibration of the measured color intensity with a color standard reduced the variation of the results and gave a significant output when the auto-focused images were taken under the condition of common indoor environment.
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With the help of micro-electromechanical systems (MEMS) and complementary metal-oxide-semiconductor (CMOS) technology, a portable micro gas chromatography ([Formula: see text]) system for lung cancer associated volatile organic compounds (VOCs) detection is realized for the first time. The system is composed of an MEMS preconcentrator, an MEMS separation column, and a CMOS system-on-chip (SoC). The preconcentrator provides a concentration ratio of 2170. The separation column can separate more than seven types of lung cancer associated VOCs. The SoC is fabricated by a TSMC [Formula: see text] 2P4M process including the CMOS VOCs detector, sensor calibration circuit, low-noise chopper instrumentation amplifier (IA), 10 bit analog to digital converter, and the microcontrol unit (MCU). Experimental results show that the system is able to detect seven types of lung cancer associated VOCs (acetone, 2-butanone, benzene, heptane, toluene, m-xylene, 1,3,5-trimethylbenzene). The concentration linearity is [Formula: see text] and the detection sensitivity is up to 15 ppb with 1,3,5-trimethylbenzene.
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A highly sensitive on-site colorimetric forensic sensor has been developed for the quantitative detection of hydrogen sulfide and ammonia gases. The sensor consists of metal-ion-modified silica-gel powders placed in a glass tube. The powder color changes upon reaction with toxic hydrogen sulfide and ammonia gases. It is capable of easily detecting toxic gases in the concentration range between 100 ppm, which is considered as immediately dangerous to life and health, and 3000 ppm, which may cause death, by using a glass tube with an inner diameter of 3 mm. As the sensor reported here is insensitive to environmental conditions such as temperature or humidity, and is featured by simplicity, fast response, high sensitivity, and easily understandable results based on absolute affirmative/negative response, it is expected to be effectively used for on-site applications such as testing the existence of toxic gases in confined working and industrial spaces.
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In 2010, the research on adsorbing diesel by biomass materials was carried out in our lab. Consistent with previous studies, both floating and adsorption performance of thermally modified biomass were improved, while the cost increased a lot. Inspired by previous studies on oil-absorbing composite materials, both the floating and sorption performance of mechanically mixed composite of cattail and reed were experimentally investigated in 2012, and the factors affecting removal rates were optimized by orthogonal experimental method. The result showed that adsorption capacity of cattail-reed composite was larger than reed, and even larger than the superposition value of cattail and reed. The buoyancy of reed sharply decreased under oscillation conditions, while cattail and the composite were lesser. The optimum conditions for removal rate of cattail were as follows: adsorbent dosage of 0.7 g, oil film thickness of 0.55 mm, oscillation frequency of 0 r/min. Under the same conditions, the particle size of reed that could remove most of the oil was 380~500 μm and the best removal rate of the composite was found when the mass ratio of cattail and reed with the same particle size was 1:4.
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The detection of carbon monoxide in solution and air has been achieved using simple, inexpensive systems based on the vinyl complexes [M(CHCHR)Cl(CO)(BTD)(PPh3 )2 ] (R=aryl, BTD=2,1,3-benzothiadiazole). Depending on the nature of the vinyl group, chromogenic and fluorogenic responses signalled the presence of this odourless, tasteless, invisible, and toxic gas. Solutions of the complexes in CHCl3 underwent rapid change between easily differentiated colours when exposed to air samples containing CO. More significantly, the adsorption of the complexes on silica produced colorimetric probes for the naked-eye detection of CO in the gas phase. Structural data for key species before and after the addition of CO were obtained by means of single X-ray diffraction studies. In all cases, the ruthenium and osmium vinyl complexes studied showed a highly selective response to CO with exceptionally low detection limits. Naked-eye detection of CO at concentrations as low as 5 ppb in air was achieved with the onset of toxic levels (i.e., 100 ppm), thus resulting in a remarkably clear colour change. Moreover, complexes bearing pyrenyl, naphthyl, and phenanthrenyl moieties were fluorescent, and greater sensitivities were achieved (through turn-on emission fluorescence) in the presence of CO both in solution and air. This behaviour was explored computationally using time-dependent density functional theory (TDDFT) experiments. In addition, the systems were shown to be selective for CO over all other gases tested, including water vapour and common organic solvents. Supporting the metal complexes on cellulose strips for use in an existing optoelectronic device allows numerical readings for the CO concentration to be obtained and provision of an alarm system. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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Recent progress in amperometric electrochemical gas sensing is reviewed. Topics covered include the use of room temperature ionic liquids (RTILs) as solvents in gas sensors, the advantageous use of micro-electrodes rather than macro-electrodes, membrane free devices and intelligent gas sensors including the simultaneous monitoring of temperature and humidity via voltammetric methods.
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In this paper, we propose tapered reflectors having stair-like structures that focus scattered infrared (IR) rays to enhance the detection performance of a non-dispersive IR (NDIR) CO2 sensor. We demonstrate that the sensitivity of the output voltage is increased by 2 and 1.27 times in simulations and experiments, respectively, compared with the case when conventionally tapered reflectors are used. Through applying a stair-like structure inside the tapered optical cavity, scattered IR rays are condensed, and more accurate CO2 concentration measurements are possible. In addition, we show that the output voltage changes only slightly with temperature and humidity variations compared with the conventionally tapered optical cavity. Because the proposed structure can be applied to any type of optical cavity without major modifications, we expect that it can resolve the performance limitations of low-end NDIR gas sensors.
Article
A sensitive Polyaniline (PANI)/ titanium dioxide (TiO2) based toxic gas sensor deposited on quartz crystal microbalance (QCM) chip was fabricated and developed through electrostatic layer-by-layer (LbL) self-assembly (SA) with polyaniline (PANI) and titanium dioxide (TiO2) sol as original materials. The synthesis process and the obtained nanocomposite were confirmed through home-made measurement set-up, field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), fourier transform infrared spectroscopic (FTIR) and X-ray diffraction (XRD), which demonstrates an thin PANI/TiO2 nanocomposite sensing film was successfully achieved by LbL self-assembly. The sensor response was found greatly influenced by the number of deposited layers. The resulting PANI/TiO2 based gas sensor exhibited good sensitivity and smooth shift in terms of responses based on frequency data than that based on resistance data. It exhibited high sensitivity toward 10 ppm of three different toxic gases (ammonia, hydrogen sulfide and trimethylamine) with evident frequency shift, fast response and recovery time. The sensor was further demonstrated possessing excellent reversibility, long-term stability, as well as accepted selectivity with significant selectivity toward NH3, and trimethylamine (TMA), and H2S followed by. In real-time application, the designed corresponding examination set-up based on the obtained PANI/TiO2 based sensor exhibited excellent performance and accurate evaluation for three typical foodstuffs. The PANI/TiO2 nanocomposite based gas sensor coated on QCM substrate via LbL self-assembly provides a promising efficient sensor to detect toxic gases in relative low concentrations.
Article
A new type of chemical sensor for gaseous nitrogen oxides (NOx, the sum of NO and NO2) has been fabricated by combining a porous glass-based NO2 sensing chip with an oxidizing agent. In this device, NO is first oxidized to NO2 over the oxidizer on a porous glass sheet (8 mm square, 1 mm thick) prepared by soaking in a sulfuric acid/potassium permanganate solution, after which the NO2 is detected by a second chip, the same size as the oxidizing chip, impregnated with Saltzman's reagent. A sensor of this type placed in a miniature aluminum holder (3 × 5 × 1.5 cm) was passively exposed to air containing ppm levels of NO or NO2. As a result, the chip changed from colorless to dark red and a plot of absorbance at 525 nm against the total exposure (defined as the sum of the product of the instantaneous gas concentration by the exposure interval) was linear. Based on the slope of the plot obtained from the NO2 exposure trials, the detection limit of the sensor was approximately 0.2 ppm NO2 assuming a 1 h exposure. It was also found that these devices exhibited equivalent sensitivity to both NO and NO2, indicating that these sensors are capable of measuring the combined NO and NO2 concentration.
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In recent years, the need of measurement and detection of samples in situ or with very small volume and low concentration (low sub parts per billion) is a cause for going to miniaturize systems via micro electromechanical system (MEMS) technology. Gas chromatography (GC) is a common technique that is widely used for separating and measuring the semi volatile and volatile compounds. Conventional GCs are bulky and cannot be used for in situ analysis, hence in the last decades many studies have been reported with the aim of designing and developing chip-based GC. The focus of this review is to follow and investigate the development and the achievements in the field of chip-based GC and its components from beginning up to now.