Gas Sensors Based on Thin-Film Transistors

Gu C., Sun L., Zhang T., Li T., and Zhang X., High-sensitivity phthalocyanine LB film gas sensor based on field effect transistors. Thin Solid Films, 327-329, 383-386, 1998. 

L. Torsi, A. Dodabalapur, L. Sabbatini, and P. G. Zambonin, Multi-parameter gas sensors based on organic thin-film transistors , Sensors And Actuators B - Chemical 67, 312 (2000). 

Torsi L (2000) Novel applications of organic based thin film transistors. Microelectron Reliab 40 779-782 Torsi L, Dodabalapur A (2005) Organic thin-film transistors as plastic analytical sensors. Anal Chem 77 381-387 Torsi L, Dodabalapur A, Sabbatini L, Zambonin PG (2(XX)) Mrrlti-parameter gas sensors based on organic thin-... 

Following these CNT electronic gas sensor studies, many other methods have been explored focusing on the reduction of fabrication cost. Snow et al. demonstrated that a low-density random network of SWCNTs can be fabricated into p-type thin-fllm transistors [Figure 14.7(c)] with a fleld-effect mobility of about 10 cm / Vs and an on-to-off ratio of about 10 [65]. They demonstrated that such thin-fllm transistors can detect dimethyl methylphosphonate (DMMP), a simulant for the nerve agent sarin, at sub-ppb levels [45]. SWCNT network transistors have also been transferred to polymer substrates to form flexible electronic gas sensors [66]. Other resistive sensors based on random SWCNT network [47] or MWCNT films [41] have also been reported. Besides the cost, CNT network and thin-film sensors increase the statistical reliability by averaging out the response at many adsorption sites. This is particularly important when gas concentration is extremely small. 

A number of physical devices with chemical sensitivity have been developed previously, including the quartz crystal microbalance (QCM) and other acoustic wave devices, semiconductor gas sensors, and various chemically sensitive field effect transistors. However, based on their intrinsic detection principles, most of the known solid state chemical sensors are not selective, i.e., they respond to more than one or a few chemical species. There is an urgent demand for new families of selective, microscope sensors that can eventually be integrated into microelectronic circuits. We have embarked on a program aimed at the design of conceptually new microporous thin films with molecular recognition capabilities. On the surface of chemical sensors, these membranes will serve as "molecular sieves that control access of selected target molecules to the sensor surface. 

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