Organic transistor chemical sensors

L. Wang, D. Fine, and A. Dodabaiapur, Nanoscale Chemical Sensor Based on Organic Thin Film Transistors , Applied Physics Letters... 

Wang, L., Fine, D., Torsi, L., and Dodabalapur, A., Nanoscale organic and polymeric field-effect transistors as chemical sensors. Anal. Bioanal. Chem., 384, 310, 2006. Gruner, G., Carbon nanotube transistors for biosensing applications. Anal. Bioanal. Chem., 384, 322, 2006. 

Kumar, A., Sinha, J., 2008. Electrochemical transistors for applications in chemical and biological sensing. In Bernards, D., MaUiaras, G., Owens, R. (Eds.), Organic Semiconductors in Sensor Applications. Springer, Heidelberg (Berlin). 

The presence of flexible side-chains make them soluble in common organic solvents [98,204-7]. These polymers have been proved by solid-state NMR and small-angle X-ray diffraction measurements to have hexagonal columnar structures in which the phthalocyanine cores are horizontally stacked with respect to the columnar axis, even at ambient temperatures [107,139,207]. The rigid rod nature of these polymers have been proved experimentally [207,208]. Their completely hydrophobic polymer allows for the controlled and highly reproducible deposition of ultra-thin films. LB films are used as branes in field effect transistors (PET S) and chemical sensors [209]. Devices based on the LB films show stable electroactivity and the electrodes show an almost Nemstian response. The change of pH in the electrolyte does not show any long time drifts. 

The science of chemical sensors is being studied at Manchester University for the use and application of conducting polymers [4]. Derivatives of polyaniline, polythiophene, polypyrrole and poly(phenylene vinylene) doped with various ions have been investigated as chemical sensors for biosensors, volatile organic compounds, polymer field-effect gas-sensitive transistors and optical sensors based on electrochromic properties. 

Conducting polymers are being considered for a number of organic electronic device apphcations such as light-emitting diodes [47, 48], thin film transistors [49-51], super-capacitors [52-56], photovoltaic cells [57-59], and chemical sensors [60-66]. Some of the most exciting and important applications are expected from biomedical devices, where they have been considered as actuators [7, 67-71] and sensors [4, 7, 67, 72-78]. 

There has recently been considerable interest in the detection and identification of air-borne volatile compounds in such diverse areas as quality control of perfume to detection of toxic gases. Miniaturization, the potential low cost of sensors and the variety of applications promise an enormous market (29, 30), Chemical sensors (29) for volatile compounds operate on varied principles and can be classified according to the method of functioning into basic groups such as electrical (field-effect transistors, metal oxide semiconductors and organic semiconductors), optical (spectrophotometric, luminescence, optothermal) and sensors that are sensitive to a change of mass (piezoelectric and acoustosurface). 

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