基于氧化铝陶瓷的无线无源湿度传感器的制备和测试

Fabrication and Measurements of Wireless Passive Humidity Sensor Based on the Alumina Ceramic

通过湿度感应技术与近场电磁耦合原理相结合,构成了基于氧化铝陶瓷的无线无源湿度传感系统。此传感器包含叉指电容与电感线圈构成的LC谐振电路和由聚酰亚胺薄膜构成的湿敏结构。当聚酰亚胺薄膜吸收水分子后,聚酰亚胺和水组成的复合体系的介电常数发生变化,导致LC电路的谐振频率发生改变,通过读取天线将传感器频率信号读取出来。搭建湿度测试平台对传感器进行测试,结果表明传感器的谐振频率随着密闭环境中空气湿度的线性增大而呈线性减小的趋势。当湿度从50%RH变化到88%RH的时候,传感器谐振频率从113.712 1 MHz变化到92.311 5 MHz,灵敏度为0.545MHz/%RH。

The wireless passive humidity sensing system based on alumina ceramic is formed by combining the humidity sensing technology and the principle of near-field electromagnetic coupling theory. The sensor contains lumped resonant circuit which was constituted by interdigital capacitor and inductor coil and humidity sensitive structure formed by polyimide film. The dielectric constant of mixture of polyimide film and water changes when polyimide film absorbed hydrone,which lead to the change of sensor resonant frequency,and readout the sensor signal by reader antenna. Humidity measurement platform was setup to test the sensor,and the results show that the resonant frequency of the sensor decreases linearly with increasing humidity in the air. The resonant frequency of sensor range from 113. 712 1 MHz to 92. 311 5 MHz with the humidity changes from 50% RH to 88% RH and the sensitivity is 0. 545 MHz / % RH.