High‐Performance Proximity Sensors with Nanogroove‐Template‐Enhanced Extended‐Gate Field‐Effect Transistor Configuration

Abstract

AbstractIn recent years human–machine interaction has become increasingly important in industrial applications and daily life. Proximity sensors are expected to become an important part of such systems. The mechanisms of these sensors are usually based on ultrasound, capacitance, triboelectric effect, optical imaging or semiconducting devices. The fabrication and sensing performance of solution‐based organic transistor proximity sensors is reported. To enhance electrical performance, nanogroove templates are introduced to guide the oriented growth of organic semiconducting layer. The templates are realized by friction‐transferring polytetrafluoroethylene thin layers onto SiO2/Si substrates. An extended gate structure for proximity sensing is designed, in which one end of a silver wire is electrically connected with the gate of the transistor and the other end serves as the sensing end. Proximity sensing is characterized by bringing various charged stimuli close to the sensor and recording the resulting change in drain current. The sensor showed good repeatability during the approach and withdrawal of a stimulus. A maximum current response of 2.2 μA between distances of 3 mm and 53 mm and distance sensitivity of 2.5 nA mm‐1 at a distance of 13 mm are obtained when a charged polytetrafluoroethylene rod is moved up and down above the sensing end.