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Enhanced Sensitivity of Gas Sensor Based on Poly(3-hexylthiophene) Thin-Film Transistors for Disease Diagnosis and Environment Monitoring

Departamento de Engenharia de Sistemas Eletrônicos, Escola Politécnica da Universidade de São Paulo (EPUSP), Av. Prof. Luciano Gualberto, trav. 3, n. 158, Cidade Universitária, CEP 05508-900, São Paulo-SP, Brasil
Instituto Superior Politécnico José Antonio Echeverría (ISPJAE), Centro de Investigaciones de Microelectrónica (CIME), Antigua Carretera de Vento, km 8 1/2, Boyeros, CP 10800 La Habana, Cuba
EMBRAPA Instrumentação, Rua Quinze de Novembro, 1452-Centro, CEP 13560-970 São Carlos, SP, Brasil.
Pontifícia Universidade Católica de São Paulo (PUC-SP), Rua Marquês de Paranaguá, 111-Consolação, CEP 01303-050 São Paulo-SP, Brasil
Instituto de Física de São Carlos–USP, Av. Trabalhador Sãocarlense 400, CEP 13566-590 São Carlos-SP, Brasil
Centro Universitário Central Paulista–UNICEP, Rua Miguel Petroni 5111, CEP 13563-470 São Carlos-SP, Brasil
Author to whom correspondence should be addressed.
Academic Editor: Michael Tiemann
Sensors 2015, 15(4), 9592-9609;
Received: 23 February 2015 / Revised: 27 March 2015 / Accepted: 16 April 2015 / Published: 22 April 2015
(This article belongs to the Special Issue Gas Sensors—Designs and Applications)
PDF [1158 KB, uploaded 23 April 2015]


Electronic devices based on organic thin-film transistors (OTFT) have the potential to supply the demand for portable and low-cost gadgets, mainly as sensors for in situ disease diagnosis and environment monitoring. For that reason, poly(3-hexylthiophene) (P3HT) as the active layer in the widely-used bottom-gate/bottom-contact OTFT structure was deposited over highly-doped silicon substrates covered with thermally-grown oxide to detect vapor-phase compounds. A ten-fold organochloride and ammonia sensitivity compared to bare sensors corroborated the application of this semiconducting polymer in sensors. Furthermore, P3HT TFTs presented approximately three-order higher normalized sensitivity than any chemical sensor addressed herein. The results demonstrate that while TFTs respond linearly at the lowest concentration values herein, chemical sensors present such an operating regime mostly above 2000 ppm. Simultaneous alteration of charge carrier mobility and threshold voltage is responsible for pushing the detection limit down to units of ppm of ammonia, as well as tens of ppm of alcohol or ketones. Nevertheless, P3HT transistors and chemical sensors could compose an electronic nose operated at room temperature for a wide range concentration evaluation (1–10,000 ppm) of gaseous analytes. Targeted analytes include not only biomarkers for diseases, such as uremia, cirrhosis, lung cancer and diabetes, but also gases for environment monitoring in food, cosmetic and microelectronics industries. View Full-Text
Keywords: organic thin-film transistors; gas sensors; P3HT; volatile organic compounds organic thin-film transistors; gas sensors; P3HT; volatile organic compounds

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Cavallari, M.R.; Izquierdo, J.E.E.; Braga, G.S.; Dirani, E.A.T.; Pereira-da-Silva, M.A.; Rodríguez, E.F.G.; Fonseca, F.J. Enhanced Sensitivity of Gas Sensor Based on Poly(3-hexylthiophene) Thin-Film Transistors for Disease Diagnosis and Environment Monitoring. Sensors 2015, 15, 9592-9609.

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