Performance Enhanced Humidity Sensor by In-Situ Integration of Nanoforests

In this letter, we report a high performance humidity sensor composed of a nanoforest-based sensing capacitor, a thermistor, a micro-heater, and a reference capacitor. Compared with traditional polyimide-based humidity sensors, sensitivity of the nanoforest-based one is significantly improved by 15 times in a relative humidity range of 10-90% RH. Meanwhile, integration of a micro-heater into the humidity sensor can reduce the humidity response time by 8 s. The use of the reference capacitor and the micro-heater can help to eliminate parasitic capacitance and to obtain higher accuracy. In addition, the fabrication process of this sensor is simple and compatible with CMOS processes, thus such a humidity sensor is suitable for batch production and has potential to replace existing sensors with low performance.