Humidity sensor based on piezoresistive microcantilever with inkjet printed PEDOT/PSS sensing layers

In this work, a new humidity sensor is developed by employing piezoresistive microcantilever with inkjet printed PEDOT/PSS sensing layers. 200 μm long, 50 μm wide and 3.75 μm thick microcantilever is designed and fabricated by PolyMUMP, which is a commercial Multi-User MEMS Process. The polysilicon piezoresistive layer in the microcantilever acts as a transduction component that will change its resistance when there is bending of microcantilever due adsorbed water molecules on PEDOT/PSS sensing layers. PEDOT/PSS layers are directly patterned on microcantilever by a commercial Dimatrix material inkjet printer. The resistances of microcantilever sensors are monitored as a function of humidity, which is simultaneously measured by a commercial humidity sensor. The resistance value is found to decrease with the humidity and the calibration curve of resistance change is linearly proportional to the percent of relative humidity in range from 20.3-66.3 %RH with high sensitivity. The results show that the piezoresistive microcantilever sensor with inkjet printed PEDOT/PSS sensing layers is a promising candidate for humidity sensing.