@misc{LangeMirsky, author = {Lange, Ulrich and Mirsky, Vladimir M.}, title = {Electroanalytical measurements without electrolytes: Conducting polymers as probes for redox titration in non-conductive organic media}, series = {Analytica Chimica Acta}, volume = {744}, journal = {Analytica Chimica Acta}, issn = {0003-2670}, doi = {10.1016/j.aca.2012.07.024}, pages = {29 -- 32}, abstract = {Electroanalytical methods have been applied only in conducting media. An application of conducting polymers allows to overcome this limitation. If such material is in electrochemical equilibrium with dissolved redox active species, its electrical conductivity depends on the redox potential of these species. Therefore, conductometric measurements with conducting polymers can provide about the same information as classical redox electrodes. The approach was applied for redox titration. Equivalent points obtained by this titration in aqueous and organic electrolytes were identical. Then the approach was applied for determination of bromine number by redox titration in non-conducting organic phase.}, language = {en} } @misc{LangeMirsky, author = {Lange, Ulrich and Mirsky, Vladimir M.}, title = {Polythiophene films on gold electrodes: A comparison of bulk and contact resistances in aqueous and organic media}, series = {Journal of Solid State Electrochemistry}, volume = {15}, journal = {Journal of Solid State Electrochemistry}, number = {11}, issn = {1433-0768}, doi = {10.1007/s10008-011-1450-4}, pages = {2377 -- 2382}, abstract = {Recently, developed technique for separated analysis of bulk and contact resistance was applied for the investigation of polythiophene films electropolymerized in boron trifluoride diethylether. Kinetics of polymer resistance and for the first time of the contact resistance during polymer oxidation and reduction were characterized. Influence of electrochemically controlled oxidation state on the polymer bulk and the polymer/metal contact resistance was measured in aqueous and organic environment. Variation of the electrical potential from -0.2 to 1.1 V vs. Ag/AgCl (sat) leads to an increase of the polymer conductivity for about three orders of magnitude and to a decrease of the contact resistance for about three orders of magnitude. The potential dependence of the two resistances was different, especially at high anodic potentials. In organic solution, the change of both resistances was more than six orders of magnitude. The results were compared with electrochemical and spectroelectrochemical data, a difference in the material behavior depending on the electrolyte solvent was observed. The influence of electrical potential on polymer resistance in aqueous solution was explained quantitatively by a three-state model with the values of oxidation potential +0.3 and +1.2 V.}, language = {en} } @misc{LangeMirsky, author = {Lange, Ulrich and Mirsky, Vladimir M.}, title = {Integrated electrochemical transistor as a fast recoverable gas sensor}, series = {Analytica Chimica Acta}, volume = {687}, journal = {Analytica Chimica Acta}, number = {1}, issn = {0003-2670}, doi = {10.1016/j.aca.2010.12.008}, pages = {7 -- 11}, abstract = {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.}, language = {en} } @misc{LangeMirsky, author = {Lange, Ulrich and Mirsky, Vladimir M.}, title = {Chemiresistors based on conducting polymers: A review on measurement techniques}, series = {Analytica Chimica Acta}, volume = {687}, journal = {Analytica Chimica Acta}, number = {2}, issn = {0003-2670}, doi = {10.1016/j.aca.2010.11.030}, pages = {105 -- 113}, abstract = {This review covers the development of measurement configurations for chemiresistors based on conducting polymers. The simplest chemiresistors are based on application of a two-electrode technique. Artifacts caused by contact resistance can be overcome by application of a four-electrode technique. Simultaneous application of the two- and four-electrode measurement configurations provides an internal control of sensor integrity. An incorporation of two additional electrodes controlling the redox state of chemosensitive polymers and connecting to the measurement electrodes through liquid or (quasi)solid electrolyte results in a six-electrode technique; an electrically driven regeneration of such sensors allows one to perform fast and completely reversible measurements.}, language = {en} } @misc{LangeHirschMirskyetal., author = {Lange, Ulrich and Hirsch, Thomas and Mirsky, Vladimir M. and Wolfbeis, Otto S.}, title = {Hydrogen sensor based on graphene - palladium nanocomposite}, series = {Electrochimica Acta}, volume = {56}, journal = {Electrochimica Acta}, number = {10}, issn = {0013-4686}, doi = {10.1016/j.electacta.2010.10.078}, pages = {3707 -- 3712}, abstract = {A composite material was prepared from graphene and palladium nanoparticles (PdNP) by layer-by-layer deposition on gold electrodes. The material was characterized by absorption spectroscopy, scanning electron microscopy, Raman spectroscopy and surface plasmon resonance. Cyclic voltammetry demonstrated the presence of electrocatalytic centers in the palladium decorated graphene. This material can serve as a sensor material for hydrogen at levels from 0.5 to 1\% in synthetic air. Pure graphene is poorly sensitive to hydrogen, but incorporation of PdNPs increases its sensitivity by more than an order of magnitude. The effects of hydrogen, nitrogen dioxide and humidity were studied. Sensor regeneration is accelerated in humid air. The sensitivity of the nanocomposite depends on the number of bilayers of graphene-PdNPs.}, language = {en} } @misc{LangeMirsky, author = {Lange, Ulrich and Mirsky, Vladimir M.}, title = {Chemosensitive nanocomposite for conductometric detection of hydrazine and NADH}, series = {Electrochimica Acta}, volume = {56}, journal = {Electrochimica Acta}, number = {10}, issn = {0013-4686}, doi = {10.1016/j.electacta.2010.08.092}, pages = {3679 -- 3684}, abstract = {A new chemosensitive material based on palladium nanoparticles and PEDOT-PSS is described. The composite was characterized by transmission electron microscopy, cyclic voltammetry and in situ resistance measurements. The material was applied for conductometric detection of hydrazine and NADH. Upon exposure to these analytes PEDOT is reduced leading to an increase in its conductance. This process is catalyzed by palladium. A model for description of the potential dependence of polymer conductivity was suggested, tested and applied for the development of new calibration procedure of chemiresistors based on electroactive polymers.}, language = {en} } @misc{LangeMirsky, author = {Lange, Ulrich and Mirsky, Vladimir M.}, title = {Separated analysis of bulk and contact resistance of conducting polymers: comparison of simultaneous 2- and 4-point measurements with impedance measurements}, series = {Journal of Electroanalytical Chemistry}, volume = {622}, journal = {Journal of Electroanalytical Chemistry}, number = {2}, issn = {1572-6657}, doi = {10.1016/j.jelechem.2008.06.013}, pages = {246 -- 251}, abstract = {Simultaneous measurements of conductive polymer by two-and four-point techniques were used for evaluation of the contact resistance for the polymer/metal interface. An experimental validation of this approach was performed for polypyrrole electrochemically deposited on gold electrodes. The dependence of contact resistance on the electrode potential versus reference electrode was measured. The results were compared with the corresponding dependence obtained from impedance spectroscopy. Both techniques provide almost identical data while the new approach is easier, faster and independent on selection of equivalent circuits.}, language = {en} } @misc{LangeRoznyatovskayaMirsky, author = {Lange, Ulrich and Roznyatovskaya, Nataliya V. and Mirsky, Vladimir M.}, title = {Conducting polymers in chemical sensors and arrays (invited review)}, series = {Analytica Chimica Acta}, volume = {614}, journal = {Analytica Chimica Acta}, number = {1}, issn = {0003-2670}, doi = {10.1016/j.aca.2008.02.068}, pages = {1 -- 26}, abstract = {The review covers main applications of conducting polymers in chemical sensors and biosensors. The first part is focused on intrinsic and induced receptor properties of conducting polymers, such as pH sensitivity, sensitivity to inorganic ions and organic molecules as well as sensitivity to gases. Induced receptor properties can be also formed by molecularly imprinted polymerization or by immobilization of biological receptors. Immobilization strategies are reviewed in the second part. The third part is focused on applications of conducting polymers as transducers and includes usual optical (fluorescence, SPR, etc.) and electrical (conductometric, amperometric, potentiometric, etc.) transducing techniques as well as organic chemosensitive semiconductor devices. An assembly of stable sensing structures requires strong binding of conducting polymers to solid supports. These aspects are discussed in the next part. Finally, an application of combinatorial synthesis and high-throughput analysis to the development and optimization of sensing materials is described.}, language = {en} } @incollection{LangeRoznyatovskayaHaoetal., author = {Lange, Ulrich and Roznyatovskaya, Nataliya V. and Hao, Qingli and Mirsky, Vladimir M.}, title = {Conducting polymers as artificial receptors in chemical sensors}, series = {Artificial receptors for chemical sensors}, booktitle = {Artificial receptors for chemical sensors}, editor = {Mirsky, Vladimir M. and Yatsimirsky, Anatoly K.}, publisher = {Wiley-VCH}, address = {Weinheim}, isbn = {978-3-527-32357-9}, doi = {10.1002/9783527632480.ch12}, pages = {363 -- 392}, language = {en} } @misc{TsakovaIvanovLangeetal., author = {Tsakova, Vessela T. and Ivanov, Svetlozar D. and Lange, Ulrich and Stoyanova, Aneliya and Lyutov, Vladimir V. and Mirsky, Vladimir M.}, title = {Electroanalytical applications of nanocomposites from conducting polymers and metallic nanoparticles prepared by layer-by-layer deposition}, series = {Pure and Applied Chemistry}, volume = {83}, journal = {Pure and Applied Chemistry}, number = {2}, issn = {1365-3075}, doi = {10.1351/PAC-CON-10-08-01}, pages = {345 -- 358}, abstract = {Layer-by-layer (LbL) deposition is a convenient technique for the formation of ultra-thin nanocomposite layers containing metallic nanoparticles (NPs) and conducting polymers (CPs). The advantages of this approach for producing composite layers suitable for electroanalytical applications are discussed. Examples of electroanalytical applications of LbL-deposited composites are presented. Composite layers consisting of polyaniline (PANI) and Pd NPs are used for hydrazine oxidation. The PANI-Au NPs system is applied for dopamine (DA) and uric acid (UA) oxidation.}, language = {en} }