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
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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 · 6.16 Impact Factor
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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 · 3.84 Impact Factor
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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 01/2015; 207. DOI:10.1016/j.snb.2014.10.086 · 3.84 Impact Factor

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