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

A flexible organic thin-film transistor humidity sensor was developed by employing moisture-responsive poly (acrylic acid) as dielectric layer, which shows reversibly linear response to environmental humidity and can work well with a low driven voltage of 2 V due to electrical double layer generation. [Display omitted] •A reversibly linear response flexible OTFT humidity sensor was developed.•The electrical double layer formation significantly the energy consumption of the sensors.•The sensitivity of the fabricated sensor can be enhanced 15-fold by tuning the gate voltage.•A fast response time of around 4 s was achieved.•The prepared sensor can be integrated into various miniaturized devices for portable sensor development. 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.