五苯環有機薄膜電晶體的氨氣感測器研究

Abstract

近年來有機薄膜電晶體感測器引起了大量的研究，在醫療的肝病檢測上，非侵入式的氨氣感測器可藉由檢測病人的呼氣氨濃度，取代傳統的血氨濃度檢測。為了能夠將有機薄膜電晶體真正應用到醫療的氨氣檢測上，我們必須將其對氨氣的感測能力提升至0.5~5 ppm。 透過五苯環有機薄膜電晶體在不同氨氣濃度下的電性量測分析，如電流、臨界電壓、載子遷移率、次臨界電壓等參數，形成多參數的氣體感測器，為了能提升其對氨氣的感測能力，我們透過UV光改變其PMMA介電層的官能基，使元件對氨氣的反應提升至0.5 ppm。此外，我們也探討了環境中的水氣分子對元件的影響，以及元件對其他氣體的反應，如氮氣、酒精、二氧化碳、丙酮、甲烷等，建立其對氣體選擇性。綜合以上的研究，我們可以確立五苯環有機薄膜電晶體在氨氣感測的可能性，使其更進一步的應用到醫療檢測上。

Non-invasive ammonia sensors are attractive for the diagnoses of a variety of chronic diseases such as liver cirrhosis. A low cost pentacene-based organic thin film transistor (OTFT) fabricated by a novel and simple process was demonstrated to be highly sensitive and specific for ammonia gas. Measurement parameters of OTFT device characteristics for ammonia detection were investigated. The significant variations of the turn-on current, intrinsic mobility, subthreshold swing and threshold voltage (Vth) were observed. The OTFT device detected low concentration (0.5~5 ppm) ammonia gas at room temperature that can distinguish between healthy person and patients with liver cirrhosis and renal failure. The sensitivity of the device was further enhanced with a simple UV irradiation treatment to modify the functional-end groups of poly(methyl methacrylate) (PMMA) dielectric layer. Possible interferences for ammonia detection such as humidity effect, recovery phenomenon, and sensing selectivity among nitrogen, alcohol, carbon dioxide, acetone, methane and ammonia were also discussed. We concluded that the proposed pentacene-based OTFT is a promising device for the future application in non-invasive medical diagnoses.