A Fast Response Flexible Humidity Sensor based on PTFE Micropore Substrate

With the improvement of sensing technology, flexible or stretchable humidity sensors have become a new subject in research. However, most of the flexible humidity sensors reported showed a low response of hundreds of seconds. In this paper, a fast response flexible humidity sensor based on poly tetrafluoroethylene (PTFE)micropore substrate is reported. Interdigited electrodes were fabricated on the PTFE substrate with conductive silver paste by screen-printing process. And graphene oxide dispersion was dropped to develop the sensitive layer. The morphologies of PTFE substrate and GO layers were characterized by scanning electron microscopy (SEM). energy dispersive spectrometer (EDS) analysis showed the high oxidation degree of GO layers on the sensors. The impedance of humidity sensor was measured under different relative humidity (RH) levels. The results showed the impedance modulus decreasing as a function of humidity, with a low sensitivity of 1.23 k Omega/%RH at low RH levels and high sensitivity of 11 k Omega/%RH at high RH levels. The impedance phase was also sensitive to humidity variation, which increased linearly with the sensitivity of 1.13 degrees/%RH. The response and recovery time was measured as 5.5s and 12s, respectively, which increased to 9s and 16s with the micropores covered in comparison. Thefast response and good sensitivity of the humidity sensor showed its potential applications in biomedical and wearable sensing.