Electronic Nose: Current Status and Future Trends

Institute of Physical and Theoretical Chemistry, University of Tübingen, Auf der Morgenstelle 15, Tübingen, Germany.
Chemical Reviews (Impact Factor: 45.66). 03/2008; 108(2):705-25. DOI: 10.1021/cr068121q
Source: PubMed

ABSTRACT The development of the electronic nose have paved the way for the classification of bacteria, to monitor air quality on the space shuttle, or to check the spoilage of foodstuff. However, the electronic nose still is unable to discriminated between flavors, perfumes, smells and as a replacement for the human nose. Although it has been used to detect some important nonodorant gases, it is not adapted to substances of daily importance in mammalian life such as the scent of other animals, foodstuff or spoilage. Due to such limitations, the electronic nose was developed to mimic the human nose. It turns out that the human nose's unequaled performance is not due to the high number of different human receptor cells, but their selectivity and their unsurpassed sensitivity for some analyte gases. As such, the success of the electronic nose will not rely on increasing the number of individual sensors and creating redundant information by adding more similar sensors, but rather on DNA, molecular, imprinted molecules or even mobilized natural receptors, which promise to increase the sensitivity and importantly selectivity. An increase in the sensitivity can be achieved by appropriate sample pretreatment and preconcentration techniques, whereas filters and separation units can be used to increase the selectivity and reduce interfering substances.

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    • "c o m / l o c a t e / c a r b o n and desorption of molecules [5]. In addition, irreplaceable advantages of graphene-based sensors, such as easy integration into existing technologies, high transparency, excellent flexibility, and considerable stretchability, make them highly attractive candidates for applications in flexible electronics, the next-generation ubiquitous platform [6] [7] [8] [9] [10]. "
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    ABSTRACT: Reduced graphene oxide (rGO) is one of the promising sensing elements for high-performance chemoresistive sensors because of its remarkable advantages such as high surface-to-volume ratio, outstanding transparency, and flexibility. In addition, the defects on the surface of rGO, including oxygen functional groups, can act as active sites for interaction with gaseous molecules. However, the major drawback of rGO-based sensors is the extremely sluggish and irreversible recovery to the initial state after a sensing event, which makes them incapable of producing repeatable and reliable sensing signals. Here, we show that pristine GO can be used as the active sensing material with reversible and high response to NO2 at room temperature. First-principles calculations, in conjunction with experimental results, reveal the critical role of hydroxyl groups rather than epoxy groups in changing metallic graphene to the semiconducting GO. We show that the adaptive motions of the hydroxyl groups, that is, the rotation of these groups for the adsorption of NO2 molecules and relaxation to the original states during the desorption of NO2 molecules, are responsible for the fast and reversible NO2 sensing behavior of GO. Our work paves the way for realizing high-response, reversible graphene-based room-temperature chemoresistive sensors for further functional convergence.
    Carbon 09/2015; 91:178-187. DOI:10.1016/j.carbon.2015.04.082
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    • "Therefore, the description of odors is of a great analytical importance in several fields of human activity. One of the recent trends in analytical sciences is the investigation of odors for medical diagnostics [2]. The development of sophisticated laboratory systems and small sensor devices capable of being integrated with personal and tablet computers and smartphones for odor analysis is underway to create novel diagnostic systems. "
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    ABSTRACT: Quartz crystal microbalance (QCM) sensors with porous films comprising silica nanoparticles and poly(allylamine hydrochloride) (PAH) were fabricated. The films were deposited via an electrostatic self-assembly method, and they exhibited considerable sensitivity to relative humidity. The infusion of poly(acrylic acid) (PAA) into multi-layer porous films (5 or 10 cycles) enabled the construction of a highly sensitive and selective QCM sensor device for the detection of gaseous ammonia. Two types of QCM sensors, with and without PAA, were used as sensors for the simultaneous quantitative detection of humidity and ammonia. A comprehensive Fourier transform infrared (FTIR) investigation of the fabricated films was conducted to elucidate the mechanism of the chemical interaction at the sensor device interface. Preliminary tests were conducted to detect low concentrations of ammonia in human breath, which are of clinical relevance. The results of these tests showed that the sensor can detect ammonia in human breath at pathological levels (greater than 3 ppm).
    Sensors and Actuators B Chemical 08/2015; 215. DOI:10.1016/j.snb.2015.03.103
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    • "Chemical sensor arrays can be applied not only to distinguish something " unknown " , but also to quantify its characteristics, just similarly to the human senses. For this reason, such systems, mimicking the functioning of human olfaction, taste or vision, were respectively called Electronic Nose [2] [3] [4], Electronic Tongue [5] [6] [7] [8] [9] [10] [11] and Electronic Eye [12] [13]. This new generation of smart devices was applied in many fields, such as health care, environmental and industrial monitoring, national security and food analysis. "
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    ABSTRACT: In this paper the use of multi-transduction principle for sensing materials development is reviewed. In particular, the application of porphyrin-based films to a multi-transduction Electronic Tongue system for different analytical tasks is presented. The optical response of sensing films was registered by means of Computer Screen Photoassisted Technology (CSPT) that applies familiar devices, such as computer monitor screen and web-camera, as illumination light source and signal detectors. Simultaneously the electrochemical amperometric or potentiometric response of the same sensing material was measured. Data analysis combining both signals significantly improves the performance of the Electronic Tongue, thus opening new frontiers in application of such a system.
    Sensors and Actuators B Chemical 02/2015; 207. DOI:10.1016/j.snb.2014.10.086
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