Thermally Stable and Sterilizable Polymer Transistors for Reusable Medical Devices

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 cm² V^–1 s^–1 to 1.2 and 1.1 cm² 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