Effect of analyte flow on the voltage fluctuations of gas chemiresistors

article in a collection out of WoS and Scopus

English

Understanding of sensor mechanisms and their properties is tightly bounded with characterization of electric charge transport and its fluctuations at/in active electrochemical interfaces. Stochastic behavior becomes an increasingly dominant characteristic of electrochemical systems as we probe them on the smaller scales 1,2. This stochasticity is completely hidden from the observer due to massive averaging – so many charge carriers (electron, ions or molecules) are involved that only their mean behavior is observable and a probabilistic description is unnecessary. Nevertheless, the effect of randomness may show significance in some systems, especially very small ones in comparison to the macroscopic world but larger than microscopic scale of molecules, as the averaging of the random particle motion is not so effective 1,3,4. For example, the kinetics of many physico-chemical, electrochemical, and bioelectrochemical processes is known to be accompanied by noise generation, which virtually represents the dynamic fluctuations of electric potential or current2. Even though not every sensor system is considered as a small - mesoscopis, several authors showed that fluctuation analyses represent the approach of extracting more selective response from macroscopic chemical sensors, e.g. chemiresistors5–8, surface acoustic wave sensors, and resonant sensors9. In conductometric sensors the observed fluctuations give more information than a single DC resistance value and therefore obtained results lead to the reduction of the number of gas sensors necessary for the detection of different gas mixtures by sensor arrays 7,10. The high-order statistics enables the extraction of non-conventional features and leads to significant improvements in selectivity and sensitivity 7,8 of sensors. Another way to improve selectivity and sensitivity of conductometric sensors is targeted change of their operating conditions, such as temperature modulation8,11, light exposure of sensitive layer with various intensity12, sampling-and-hold method13, transient flow modulation14,15, etc. Our motivation aims on possibility of improved selectivity by modulation of analyte flow rate around conductometric sensors at equilibrium conditions by studying voltage fluctuations. By setting different flowrate, the concentration of analytes at the surface of sensors is modulated, and the specific response patterns, which are characteristic of the analytes present, develop. The method could be adapted to both static and dynamic headspace sampling strategies. However, this contribution aims to present how the flow rate of analyte affects the voltage fluctuation of the resistive gas sensor, which has not yet been sufficiently presented (PDF) Effect of analyte flow on the voltage fluctuations of gas chemiresistors.

Gas sensor;Current fluctuations;Flow;Modulation;Amperometric;Signal-to-noise ratio

MÍVALT, F.; SEDLÁKOVÁ, V.; MAJZNER, J.; KUBERSKÝ, P.; SMULKO, J.; SEDLÁK, P.

9. 7. 2018

Gdansk

134

135

154

https://pg.edu.pl/upon2018/Book_of_Abstracts_UPoN2018.pdf