We realize a thermally stable polymer thin film transistor (TFT) that is able to endure the standard autoclave sterilization for reusable medical devices. A thermally stable semiconducting polymer poly[4-(4,4-dihexadecyl-4Hcyclopenta[1,2-b:5,4-b]dithiophen-2-yl)-alt[1,2,5]thiadiazolo [3,4c] pyridine], which is stable up to 350 °C in N2 and 200 °C in air, is used as channel layer, whereas the biocompatible SU-8 polymer is used as a flexible dielectric layer, in addition to conventional SiO2 dielectric layer. Encapsulating with in-house designed composite film laminates as moisture barrier, both TFTs using either SiO2 or SU-8 dielectric layer exhibit good stability in sterilized conditions without significant change in mobility and threshold voltage. After sterilization for 30 min in autoclave, the mobility drops only 15%; from as-fabricated mobility of 1.4 and 1.3 cm(2) V(-1) s(-1) to 1.2 and 1.1 cm(2) V(-1) s(-1) for TFTs with SiO2 and SU-8 dielectric layer, respectively. Our TFT design along with experimental results reveal the opportunity on organic/polymer flexible TFTs in sterilizable/reusable medical device application.
Keywords: medical devices; moisture-barrier; organic transistor; semiconducting polymer; thermal stability.