TY - GEN A1 - Lange, Ulrich A1 - Mirsky, Vladimir M. T1 - Integrated electrochemical transistor as a fast recoverable gas sensor T2 - Analytica Chimica Acta N2 - A new design of conductometric chemical sensors based on conducting polymers as chemosensitive elements was suggested. The sensor includes six electrodes. Four inner electrodes coated by chemosensitive polymer are used for simultaneous two- and four-point resistance measurements thus providing information on the bulk polymer resistance and on the resistance of the polymer/electrode contacts. Two outer electrodes wired to inner electrodes by polymeric electrolyte are used for electrical control of redox state of the chemosensitive polymer. The outer electrodes are connected to potentiostat as reference and counter electrodes. It allows us to control redox state of the inner (working) electrodes. This new measurement configuration, resembling chemosensitive electrochemical transistors, provides an internal test of the sensor integrity and an electrically driven sensor regeneration. It was tested as a sensor for the detection of nitrogen dioxide. Polythiophene or polyaniline was used as receptors. Cyclic voltammograms of these polymers on the sensor surface measured in air atmosphere were very similar to that measured in aqueous electrolyte. A control of conductivity of these chemosensitive polymers by electrical potential applied vs. incorporated reference electrode was demonstrated. This effect was used for the regeneration of the chemosensitive material after exposure to nitrogen dioxide: in comparison to usual chemiresistors displaying an irreversible behavior in such test even in the time scale of hours, a completely reversible sensor regeneration within few minutes was observed. KW - Gas sensor KW - Conducting polyme KW - Electrochemical transistor KW - Six-point resistance Measurement KW - Sensor recovery Y1 - 2011 U6 - https://doi.org/10.1016/j.aca.2010.12.008 SN - 0003-2670 VL - 687 IS - 1 SP - 7 EP - 11 ER - TY - GEN A1 - Wolpert, Benjamin A1 - Wolfbeis, Otto S. A1 - Mirsky, Vladimir M. T1 - Gas sensing properties of electrically conductive Cu(I) compounds at elevated temperatures T2 - Sensors and Actuators B: Chemical N2 - Changes in the electrical conductance at 240 °C of a number of copper(I) compounds including CuI, CuBr, Cu2Te, Cu12Sb4S13, (CuI)2P14, and of NiO were measured following the exposure to the gases ammonia, nitrogen dioxide, nitrous oxide, carbon monoxide, carbon dioxide, and propane. Analytical sensitivity and kinetic parameters were compared quantitatively. The high diversity of sensitivity patterns makes these compounds promising candidates for use in sensor arrays. Principal component analysis of the data obtained with a virtual sensor array enabled highly selective sensing of five of the six analytes studied using only two principle components. Activation energies of the charge transport in the materials were determined. KW - Gas sensor KW - Ammonia sensor KW - Conductometric sensor KW - Sensor array KW - Copper(I) KW - High-temperature sensing Y1 - 2009 U6 - https://doi.org/10.1016/j.snb.2009.04.042 SN - 0925-4005 VL - 142 IS - 2 SP - 446 EP - 450 ER - TY - GEN A1 - Wolpert, Benjamin A1 - Leitl, Michael A1 - Pfitzner, Arno A1 - Mirsky, Vladimir M. T1 - Chemosensitive properties of electrically conductive Cu(I)-compounds at room temperature T2 - Sensors and Actuators B: Chemical N2 - Changes of the electrical conductance of a number of inorganic copper(I) conductive compounds including Cu₁₂Sb₄S₁₃,CU₂O, CuI, CuBr and CuCl were tested on exposure to different gases and vapors, including ammonia, nitrogen monoxide, octanethiol, hydrogen chloride, acetic acid, formic acid, ethanol, humidity and piperidine. The sensitivity of the resistivity to ammonia was estimated as 2.7%/ppm for CuBr,1.4%/ppm for Cu₂O, 1.2%/ppm for CuCl, 0.013%/ppm for CuI, but only 0.0028%/ppm for Cu₁₂Sb₄S₁₃. The highest selectivity for ammonia was observed for Cu₁₂Sb₄S₁₃. The sensitivity patterns of these materials to the tested gases and vapors are very different which makes them applicable for sensor arrays for identification and quantification of these species. KW - Chemical sensor KW - Gas sensor KW - Ammonia sensor KW - Conductometric sensor KW - Chemoresistor KW - Copper(I) Y1 - 2008 U6 - https://doi.org/10.1016/j.snb.2008.06.047 SN - 0925-4005 VL - 134 IS - 2 SP - 839 EP - 842 ER - TY - GEN A1 - Samoylov, Anton V. A1 - Mirsky, Vladimir M. A1 - Hao, Qingli A1 - Swart, Claudia A1 - Shirshov, Yuri M. A1 - Wolfbeis, Otto S. T1 - Nanometer-thick SPR sensor for gaseous HCl T2 - Sensors and Actuators B: Chemical N2 - The optical properties of electrochemically polymerized N-methylaniline are changed in the presence of gaseous hydrogen chloride. This effect was used for preparation of chemical sensors with transduction based on surface plasmon resonance. The interaction of hydrogen chloride with a two nm layer of poly-(N-methylaniline) on gold leads to the shift of the surface plasmon resonance. The analysis of the resonance spectra demonstrates that the effect is caused by an increase of the imaginary component of the refractive index; a minor contribution is also provided by film condensation leading to an increase of the real component of the refractive index and a decrease in the thickness. The effect is selective and quasi-reversible. The concentration dependence of the gas effect obeys Langmuir's adsorption isotherm with a reciprocal value of the binding constant of 850 ± 160 ppm. KW - Gas sensor KW - HCI sensors KW - Surface plasmon resonance KW - Electropolymerization KW - Poly-(N-methyl-aniline) KW - Fire detector Y1 - 2005 U6 - https://doi.org/10.1016/j.snb.2004.08.029 SN - 0925-4005 VL - 106 IS - 1 SP - 369 EP - 372 ER - TY - GEN A1 - Hao, Qingli A1 - Kulikov, Valentin A1 - Mirsky, Vladimir M. T1 - Investigation of contact and bulk resistance of conductive polymers by simultaneous two- and four-point technique T2 - Sensors and Actuators B: Chemical N2 - A conventional resistance measured by two-point technique includes bulk and contact components. The contact resistance can be excluded by a four-point technique. A simultaneous use of the two- and four-point techniques allows to separate the total resistance between two electrodes for the contact and bulk parts. This approach has been used to analyze electrical coupling between metal electrodes of interdigitated structures and chemically sensitive coating formed by polyaniline (PANI). The polymer layers were deposited by electropolymerization on bare gold and platinum electrodes as well as on gold electrodes precoated by a self-assembled monolayer of 4-aminothiophenol. An exposure of the PANI films formed on interdigitated structures to gaseous HCl displays proportional changes of resistance measured by the two- and four- point techniques for platinum electrodes and for the precoated gold electrode, while a strong deviation from this proportionality was observed for the gold electrodes without precoating. The results demonstrate a high contribution of the contact resistance between PANI and bare gold electrodes into the resistance measured by the two-point technique. This contribution is small and therefore not measurable for bare platinum electrodes or for gold electrodes coated by 4-aminothiophenol. KW - Chemoresistor KW - Conductometric chemosensor KW - Electropolymerization KW - Four-point technique KW - Gas sensor Y1 - 2003 U6 - https://doi.org/10.1016/S0925-4005(03)00456-8 SN - 0925-4005 VL - 94 IS - 3 SP - 352 EP - 357 ER -