The Performance Research Of The Capacitive Humidity Sensor

The humidity sensors are studied widely with the importance of the humidity in our daily life. Lately, the capacitive humidity sensor has achieved great development for its high-sensitivity, fast-response, little-lag and easily-minisized and integrated.The more popular materials of the humidity sensor are the semiconductor -oxide ceramic and the macromolecule-polymer. The requirement for the technology of the humidity sensor will be defferent according to the applied field. On the manufacture eye, there will be great difference in performance if we take the different material, structure or technics. The article has studied two materials of porous alumina and the polyimide , analysised the mechanism of the capacitive humidity .On one hand, designing the structure size of the porous alumina , analying the capacitance using the depth and diameter and finding the method to improve the sensitivity performance is achieved in the paper. On the other hand, designing the polyimide polymer size, putting forward the cirque body structure and analysising the response time performance relying on the normalization capacitance.The studied results show that the humidity sensor will get better sensitivity when the k₁ is near to 1 and k₂ is 2.15, the hole number is about 8. 26*10⁹ cm^-2 and measturing in low frequence; The response time of the cirque body structure is only 1/10 times than the tranditional rectangular contious film and less 77. 2% for cylindrical body and can dimishes the response time greatly.