Low-voltage driven flexible organic thin-film transistor humidity sensors

Relative humidity (RH) is broadly involved in various areas, including industry, agriculture, medical engineering, as well as environments. Thus, development of a high-performance, low-energy consumption, flexible, and miniaturized RH sensing device is quite essential to meet the modern requirements. However, it is still a grand challenge to endow a RH sensor with all the above strengths. Herein, according to the electrical double layer mechanism, a RH-responsive poly (acrylic acid) is employed as a sensing layer and simultaneously a dielectric layer for fabrication of flexible organic thin-film transistor (OTFT) RH sensors, which could remarkably reduce the driven voltage of the OTFT device to 2 V. The sensitivity of such-designed sensors can be manipulated by tuning the driven voltage. Notably, all the fabricated OTFT sensing devices show reversibly linear response to RH and a fast response of around 4 s. Due to the solution-processing abilities and flexibility of the OTFT device, it can be miniaturized and integrated into multiple functional devices, e.g., soft medical devices.