![The schematic diagrams of the microfluidic device. (a) the microfluidic device and the biosensor under measuring. (b) the drawing of the microfluidic channel [25].](https://www.researchgate.net/publication/332066013/figure/fig2/AS:741590159077376@1553820280767/The-schematic-diagrams-of-the-microfluidic-device-a-the-microfluidic-device-and-the_Q320.jpg)
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Determination of L-ascorbic Acid Using MBs-AOX/GO/IGZO/Al by Wireless Sensing System and Microfluidic Framework
Abstract and Figures
In this study, the L-ascorbic acid (L-AA) biosensor based on magnetic beads-ascorbate oxidase /graphene oxide/indium gallium zinc oxide/aluminum (MBs-AOX/GO/IGZO/Al) membrane was integrated with microfluidic system in order to investigate the different sensing characteristics under the static condition and dynamic condition. The L-AA biosensor showed the average sensitivity of 78.9 mV/decade (25 °) under the static condition, and it showed the average sensitivity of 81.7 mV/decade (25 °) at the optimal flow rate (25 μL/min). Besides, the XBee module was used to apply in remote detection for L-AA biosensor, and the experimental results were shown the average sensitivity of 78.7 mV/decade (25 °). Moreover, we also investigated various experiments such as temperature effect, hysteresis effect, and life time. These experimental results would be beneficial to the development of L-AA biosensor based on electrochemical detection.
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... In our previous study [30][31][32], the detailed information of chemicals can be found, and more details of the fabrication process are illustrated. All chemicals used in this work were of analytical grade and used without further purification. ...
... The surface potential of the sensing electrode is changed further owing to the micro-variation of the pH value. According to the Nernst equation and our previous study [32,41], the sensing mechanism can follow the equation (2). ...
... The results indicated that the average sensitivities under microfluidic flow were better than under the static microfluid. In the previous study by the same research group [32], the optimal average sensitivity of the AA biosensor MBs-AO/GO/IGZO/Al was 81.7 mV/decade at the flow rate of 25 μL/min. The results were in accordance with the previous study, the optimal flow rate was still within a range of 15 μL/min to 25 μL/min. ...
In this work, we used sputtering and screen-printing technology to develop a sensitive potentiometric ascorbic acid (AA) biosensor with the magnetic beads-ascorbate oxidase/graphene oxide/zinc oxide (MBs-AO/GO/ZnO) membrane-based arrayed screen-printed electrodes (SPEs). The morphology of membranes was characterized by using a scanning probe microscope (SPM) and a field-emission scanning electron microscope (FE-SEM). The sensing characteristics were analyzed via the voltage-time (V-T) measurement system. The potentiometric arrayed AA biosensor showed the exceptional average sensitivity of 70.68 mV/decade over a wide linear range of AA concentration (7.8125 lM-2 mM), the short response time of 25 s, the lower limit of detection of (LOD) of 0.04 lM, and the excellent selectivity. Furthermore, we investigated other analytical parameters of the potentiometric arrayed AA biosensor, such as the temperature effects, the lifetime, and the average sensitivity under microfluidic flow. The optimal average sensitivity of the biosensor integrated the microfluidic framework was 72.21 mV/decade under microfluidic flow. Finally, the biosensor was applied to the remote AA detection by using the wireless sensing system. The results indicated that the average sensitivity of the potentiometric arrayed AA biosensor based on MBs-AO/GO/ZnO was 77.38 mV/decade during the monitoring in a long distance.
... Moreover, microfluidic technology offers integration of various components in a single platform [16]. Therefore, flexibility, rapid analysis, low fabrication costs, ease of implementation and disposability promote microfluidic technology to a very popular solution in biochemical sensing [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36]. AA is soluble in water, allowing the application of food microfluidics. ...
... The graphene/CuPc/PANI nanocomposite structure has been manufactured by electrolytic exfoliation technique for the determination of AA and investigation of its electrochemical characteristics [29], [30]. The complete measurement system based on the complex structure of the magnetic beads-ascorbate oxidase/graphene oxide/indium gallium zinc oxide/aluminium and the microfluidic device has been developed and tested as a biosensor of AA [31]. An AA sensor validated by means of a commercial vitamin C supplement, applying a structure based on pyrolysed photoresist films and graphene nano-sheets, has been demonstrated [32]. ...
In this paper, we present a compact microfluidic platform for selective detection of ascorbic acid. The microfluidic chip was fabricated by xurography technique with microfluidic channel placed between the silver electrodes. To increase the conductivity of the platform and enhance electron transfer process, a graphene sheet was deposited in the gap between the electrodes. The suspension of tablets with ascorbic acid and a mixture of ascorbic acid and isomalt, a sugar substitute, were injected in the microfluidic channel. Measuring electrical parameters at the silver contacts, it was possible to successfully differentiate ascorbic acid from isomalt. The sensing mechanism of the developed microfluidic platform is based on the increase of the overall conductivity with the increase of the concentration of ascorbic acid, resulting in the decrease of the resistive parameters and increase of the capacitive parameters of the proposed equivalent electrical circuit. The addition of graphene was found to improve the response linearity by 5.28% and lower the limit of detection and quantification by 12%, compared to the reference structure without graphene.
... As a limitation, the application of the developed device was not checked in real media, however, this probe could be more investigated for designing possible commercial device. In 2019, another similar wireless sensing system was developed for L-AA detection which had used magnetic beads-ascorbate oxidase/graphene oxide/indium gallium zinc oxide/aluminum (MBs-AOX/GO/IGZO/Al) membrane on the PET substrate [33]. For this purpose, the GO was deposited on the IGZO layer for providing an excellent and appropriate immobilization surface of AOX. ...
In today's world, various types of magnetic materials as an essential and inseparable part of scientific application demonstrate high potential for exploitation in different fields including bioimaging, catalysis, and energy storage. In addition, attractive and unique advantages including high surface area, conductivity, stability, and solubility have caused the high efficiency of these materials in sensing platforms. Besides, the advancement of point-of-care detection methods such as microfluidics has provided a portable sensing device with several advantages such as short response time and the lowest amounts of samples and reagents as well as being automated for efficient determination of various toxins, drugs, and cells. In this review, we attempted to review recent types of microfluidic systems based on electrochemical, optical and quartz crystal microbalance (QCM) methods which have exploited magnetic materials for designing the most efficient and sensitive microfluidic sensor based on magnetic materials.
Health applications have received greater attention with the use of the Internet of Things-IoT, due to the use of sensors for remote monitoring, not only in hospital environments, but also in domestic environments and in activities daily living. Wearable chemical sensors have been proposed in the health area for the continuous monitoring of the individual's well-being, however, the challenges related to the convergence of these two areas still require a lot of research for the solutions to be effectively applied. The objective of this paper is to present the results of a systematic literature review carried out with the purpose of highlighting the applications that employ the use of wearable chemical sensors in IoT contexts. The results found present several challenges and open questions of a promising research field involving IoT and wearable chemical sensors. Resumo. As aplicações de saúde têm recebido maior atenção com o uso de In-ternet das Coisas-IoT, por conta do uso de sensores para o monitoramento remoto, não apenas em ambientes hospitalares, mas também em ambientes domésticos e nas atividades diárias e de rotina. Sensores químicos vestíveis têm sido propostos naárea da saúde para o monitoramento contínuo do bem-estar do indivíduo, entretanto, os desafios relacionadosà convergência dessas duasáreas ainda necessitam de muita pesquisa para que as soluções sejam efetivamente aplicadas. O objetivo deste artigoé apresentar os resultados de uma revisão sistemática da literatura realizada com o propósito de destacar as aplicações que empregam o uso de sensores químicos vestíveis em contextos de IoT. Os resultados encontrados apresentam vários desafios e questões em aberto de um campo de pesquisa promissor envolvendo IoT e sensores químicos vestíveis. 1. Introdução A Internet das Coisas (IoT)é a rede de objetos físicos-dispositivos, instrumentos, veículos, edifícios e outros itens embarcados com eletrônica, circuitos, software, sen-sores e conectividade de rede-que permite que esses objetos coletem e troquem dados. A Internet das Coisas permite que objetos sejam detectados e controlados remotamente em infraestrutura de rede, criando oportunidades para uma integração mais direta do mundo físico em sistemas baseados em computação. [Gokhale et al. 2018]
As aplicações de saúde têm recebido maior atenção com o uso de Internet das Coisas - IoT, por conta do uso de sensores para o monitoramento remoto, não apenas em ambientes hospitalares, mas também em ambientes domésticos e nas atividades diárias e de rotina. Sensores químicos vestíveis têm sido propostos na área da saúde para o monitoramento contínuo do bem-estar do indivíduo, entretanto, os desafios relacionados à convergência dessas duas áreas ainda necessitam de muita pesquisa para que as soluções sejam efetivamente aplicadas. O objetivo deste artigo é apresentar os resultados de uma revisão sistemática da literatura realizada com o propósito de destacar as aplicações que empregam o uso de sensores químicos vestíveis em contextos de IoT. Os resultados encontrados apresentam vários desafios e questões em aberto de um campo de pesquisa promissor envolvendo IoT e sensores químicos vestíveis.
We fabricated a potentiometric non-enzymatic ascorbic acid sensor. The main sensing materials are molybdenum trioxide (MoO
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) film and copper oxide nanoparticles (CuO NPs). Basic sensors and sensing materials were fabricated by the screen printing technique, the radio frequency sputtering system, and the green synthesis method. The average sensitivity, linearity, and interference effects of the ascorbic acid sensor under static measurements were examined. In order to simulate dynamic measurements, we performed experiments by the microfluidic system and analyzed the best sensing characteristic at low flow rates (1.4 μL/min-7.0 μL/min) and high flow rates (10 μL/min-50 μL/min). The best average sensitivities under static and dynamic measurements are 35.26 mV/decade and 61.11 mV/decade, respectively. Ultimately, the ascorbic acid sensor achieves better stability and accuracy with the help of a unity-gain frequency and low power consumption instrumentation amplifier (UGFPCIA). This study shows that the ascorbic acid sensor can possibly achieve excellent sensing properties even without the help of enzyme and a conventional commercial chip (LT1167).
The goal of this research is to reduce the hysteresis effect of the urea biosensor modified by urease-silver nanoparticles (Ag NPs)/ruthenium dioxide (RuO
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) thin film. A new analog back-end circuit with a voltage regulation approach was proposed for hysteresis reduction. A urea biosensor based on urease-Ag NPs/RuO
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sensing film was fabricated. The sensing characteristics of the urea biosensor such as average sensitivity, response time, and interference effect, were measured by the voltage-time (V-T) measurement system. The experiment results showed that the average sensitivity and linearity of the urea biosensor in a wide range of urea solution (0.833μM-8.33 mM) were 48.73 mV/decade and 0.996, respectively. The response time was 22 seconds and the limit of detection was 0.37 μM. Moreover, the electrochemical impedance analysis (EIS) was used to analyze the charge transfer ability of urease-Ag NPs/RuO
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thin film. By applying the voltage regulation approach, the proposed analog back-end circuit can hold the response voltage of the biosensor at a stable level. Therefore, the hysteresis voltage was reduced. With the proposed backed-end circuit in urea solution cycle of 30 mg/dL → 10 mg/dL → 30 mg/dL → 50 mg/dL → 30 mg/dL, the hysteresis voltage was reduced from 4.57 mV to 3.35 mV (26% reduction) comparing with V-T measurement system. The hysteresis voltage in the opposite urea solution cycle of 30 mg/dL → 50 mg/dL → 30 mg/dL → 10 mg/dL → 30 mg/dL was reduced from 3.71 mV to 2.62 (29% reduction) mV comparing with V-T measurement system.
Internet of Things (IoT) consists of smart devices that communicate with each other. It enables these devices to collect and exchange data. Besides, IoT has now a wide range of life applications such as industry, transportation, logistics, healthcare, smart environment, as well as personal, social gaming robot, and city information. Smart devices can have wired or wireless connection. As far as the wireless IoT is the main concern, many different wireless communication technologies and protocols can be used to connect the smart device such as Internet Protocol Version 6 (IPv6), over Low power Wireless Personal Area Networks (6LoWPAN), ZigBee, Bluetooth Low Energy (BLE), Z-Wave and Near Field Communication (NFC). They are short range standard network protocols, while SigFox and Cellular are Low Power Wide Area Network (LPWAN).standard protocols. This paper will be an attempt to review different communication protocols in IoT. In addition, it will compare between commonly IoT communication protocols, with an emphasis on the main features and behaviors of various metrics of power consumption security spreading data rate, and other features. This comparison aims at presenting guidelines for the researchers to be able to select the right protocol for different applications.
Addition of reduced graphene oxide (RGO) to P25 TiO2 was made and its impacts on photocatalytic oxidation of various organic substances were studied. Although the presence of RGO in TiO2 can enhance certain TiO2-based photocatalytic reactions, it is not a universal observation that can be expected on all types of organic substances. The factor of photocatalytic activity enhancement is strongly affected by the various functional groups appeared in the organic substances. In this work, it is realised that the length of alkyl chain in alcohols and carboxylic acids have the minimum influence on the overall activity while the number of hydroxyl groups can promote the further activity enhancement in the presence of RGO.
The importance of vitamin C as a way to prevent scurvy has been known for centuries. More recent research on vitamin C has expanded beyond scurvy prevention, providing promising
evidence for additional health benefits and clinical applications. This review of scientific literature will evaluate many aspects of vitamin C including deficient versus optimal blood
plasma levels, adequate daily amounts necessary to maintain ideal levels, and the safety of higher doses. It will also focus on the importance of vitamin C as a powerful bioactive compound, and its utilization in the prevention and management of different chronic diseases. This review is necessary to express the importance of alternative healthcare methods in both preventative and clinical care. Vitamin C was chosen as a representative of this concept due to its powerful antioxidant capacity, incredibly important physiological implications, and very minimal chance
of side-effects. This review focuses on studies involving human participants that address how vitamin C is important for our health
Urea is the major end product of nitrogen metabolism in humans, which is eliminated from the body mainly by the kidneys through urine but is also secreted in body fluids such as blood and saliva. Its level in urine ranges from 7 to 20 mg/dL, which drastically rises under patho-physiological conditions thus providing key information of renal function and diagnosis of various kidney and liver disorders. Increase in urea levels in blood, also referred to as azotemia or uremia. The chronic kidney disease (CKD) or end stage renal disease (ESRD) is generally caused due to the progressive loss of kidney function. Hence, there is an urgent need of determination of urea in biological fluids to diagnose these diseases at their early stage. Among the various methods available for detection of urea, most are complicated and require time-consuming sample pre-treatment, expensive instrumental set-up and trained persons to operate, specifically for chromatographic methods. The biosensing methods overcome these drawbacks, as these are simple, fast, specific and highly sensitive and can also be applied for detection of urea in vivo. This review presents the principles of various analytical methods for determination of urea with special emphasis on biosensors. The use of various nanostructures and electrochemical microfluidic paper based analytical device (EμPAD) are suggested for further development of urea biosensors.
In this study, we proposed a flexible arrayed L-ascorbic acid (L-AA) biosensor based on the indium gallium zinc oxide (IGZO)/aluminum (Al) membrane modified by graphene oxide (GO). We used screen printing technology, thermal evaporation system and radio frequency (R. F.) sputtering system to fabricate the arrayed structure of IGZO/Al membrane. Moreover, we used GO solutions with different concentrations to deposit GO membrane onto the IGZO/Al membrane, and then we deposited the ascorbate oxidase on the GO membrane in order to increase the specificity for L-ascorbic acid. According to the experimental results, the average sensitivity and linearity of flexible arrayed IGZO/Al L-AA biosensor were 50.2 mV/decade and 0.993, respectively. After adding GO, the average sensitivity and linearity were increased up to 72.5 mV/decade and 0.996, respectively. Besides, the stability of the biosensor was investigated by drift effect and interfering effect. Moreover, Brunner-Emmet-Teller (BET) sorptometer was used to analyze the specific surface areas.
In this study, nickel oxide (NiO) was used as sensing film of flexible arrayed NiO pH sensor, and its average sensitivity could be improved by introducing oxygen gas in sputtering deposition process for NiO sensing film. It had the advantage such as portability, disposability, low cost, high flexibility, miniaturization, long-term stability for basic solution and high sensitivity (63 mV/pH) exhibited in the pH range from pH 1 to pH 13. Moreover, the characteristics of optimal NiO sensing film were investigated by using field emission scanning electron microscope. The non-ideal effects of flexible arrayed NiO pH sensor were investigated, such as drift and hysteresis effects. The drift rates for pH 1, pH 7 and pH 13 were -4 mV/hr, 3 mV/hr and 1 mV/hr, respectively. Moreover, the hysteresis voltages were within 4 mV.
In this paper, the pH sensor and glucose biosensor were integrated with microfluidic framework, and the sensing characteristics under the dynamic conditions, i.e., solution under flowing condition, were investigated. The indium-gallium-zinc oxide (IGZO), as a sensing membrane, was deposited on aluminum electrodes/polyethylene terephthalate substrate. Then, the screen-printed technology was used to accomplish the encapsulation of sensor. The glucose biosensor based on enzyme needed an extra glucose sensing membrane, which was composed of glucose oxidase (GO
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) and nafion. The glucose sensing membrane was dropped on the IGZO/Al sensing membrane. According to the experimental results, the optimal sensing characteristics of pH sensor and glucose biosensor under the dynamic conditions were better than those under the static condition (solution without flowing). The optimal average sensitivity and linearity were 56.857 mV/pH and 0.997 at 25 μL/min flow rate, respectively (in pH sensor), and 7.255 mV/mM and 0.994 at 20 μL/min flow rate, respectively (in glucose biosensor). Furthermore, the hysteresis effect and drift effect were researched for pH sensor, and the electrochemical impedance spectroscopy was used to demonstrate whether the IGZO/Al sensing membrane had been modified by GO
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and nafion and it was found that the additions of GO
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and nafion had increased the electron transfer resistance (R
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).
In this paper, the wireless sensor network (WSN) with the ZigBee standard is integrated with the flexible arrayed potentiometric sensor, such as flexible arrayed pH sensor and flexible arrayed glucose biosensor that achieve a wireless sensing system. The wireless sensing system is accomplished by the graphical language laboratory virtual instrumentation engineering workbench and the detection signals are displayed in real time in the computer. A potentiometric electrochemical method is used to measure the output signal of potential difference between the silver/silver chloride (Ag/AgCl) reference electrode and the flexible arrayed potentiometric sensor. We provide a wireless sensing system of XBee module, which has the advantages of low cost, easy operation, portable device, high accuracy, real-time monitoring, and rapid detection. According to the experimental results of flexible arrayed pH sensor and flexible arrayed glucose biosensor, the range of pH values from pH 1 to pH 13 has a good average sensitivity of 51.38 mV/pH and a linearity of 0.995, and the range of glucose solution concentration from 100 to 500 mg/dL has a good average sensitivity of 0.179 mV(mg/dL)-1 and a linearity of 0.999. The actual target in this paper is to provide a wireless sensing system for ion sensing and monitoring of human physiological data.
This paper investigated the sensing characteristics of a flexible-arrayed chlorine ion sensor, which was realized based on ruthenium oxide thin-film/polyethylene terephthalate substrate and fabricated by the screen-printed technology and the radio frequency sputtering technique. By the static measurement, the average sensitivity and the linearity of the chlorine ion sensor were 25.065 mV/pCl and 0.960 from 10(-5) to 1 M sodium chloride ( NaCl) solutions. This paper also investigated the non-ideal effect and dynamic microfluidic measurement for the flexible-arrayed chlorine ion sensor. The hysteresis potential of the flexible-arrayed chlorine ion sensor was 2.738 mV in the NaCl solutions with the cycle of 1 M. 10(-3) M -> 1 M -> 10(-1) M -> 1 M. Besides, we measured the response potentials in different concentrations from 10(-5) to 1 M NaCl solutions over 12 h, and the best drift rate of the chloride ion sensor was 0.454 mV/h in 10(-2) M NaCl solution. By the dynamic measurement of the flexible-arrayed chlorine ion sensor, the average sensitivity and the linearity were 30.758 mV/pCl and 0.985 for the flow rate of 25 mu L/min between 10(-5) and 1 M NaCl solutions. Therefore, the average sensitivity and the linearity of the dynamic measurement were better than those of the static measurement for the flexible-arrayed chlorine ion sensor.
The use of nanotechnology in bioanalytical devices has special advantages in the detection of toxins of interest in food safety and environmental applications. The low levels to be detected and the small size of toxins justify the increasing number of publications dealing with electrochemical biosensors, due to their high sensitivity and design versatility. The incorporation of nanomaterials in their development has been exploited to further increase their sensitivity, providing simple and fast devices, with multiplexed capabilities. This paper gives an overview of the electrochemical biosensors that have incorporated carbon and metal nanomaterials in their configurations for the detection of toxins. Biosensing systems based on magnetic beads or integrated into microfluidics systems have also been considered because of their contribution to the development of compact analytical devices. The roles of these materials, the methods used for their incorporation in the biosensor configurations as well as the advantages they provide to the analyses are summarised.