针对探空仪湿度传感器在高空低温、高湿恶劣环境下容易结露, 湿度波动大、电路板分布电容对测量结果有影响等问题, 研究了具有蛇形加热器的平板夹心电容式湿度传感器及其工艺制备方法, 并设计了测量电路。采用微机电系统(MEMS)加工工艺设计了加热式湿度传感器, 通过对传感器进行有限元分析, 确定了传感器表面加热区域温度分布情况, 得出了环境温度、加热功率与加热温度三者之间的函数关系。提出一种基于电容充放电及比较法的湿度测量电路, 从而有效地抑制了温度漂移和零点漂移, 减小了寄生电容对测量结果的影响。地面实验结果显示: 湿度传感器灵敏度约为2 3%RH·pF-1, 迟滞约为0.7% F·S, 重复性约为1.9%, 测量总不确定度约为4%, 时间常数约为0.5 s。本文研究的湿度传感器及其测量电路具有很好的温度稳定性, 能够在低温环境下正常工作。

Humidity sensors are easy to condense and have humidity fluctuation, moreover, their board distributed capacitances affect measurement results under a high altitude environment. Therefore, this paper proposes a sandwich plate capacitive humidity sensor integrated with a snake like platinum resistance heater and its prepared method. Then, it studies the measuring circuit for the sensor. The humidity sensor with heater was designed using Micro-electric-mechanic System(MEMS) technology, the temperature distribution of sensor surface was analyzed and the function relationship between environment temperature, heating power and heating temperature were obtained by using finite element analysis. To suppress the temperature and zero drifts effectively and reduce the influence of parasitic capacitance on measurement, a humidity measurement circuit based on the capacitor charging and comparative law was designed. The ground experimental results on the sensor show that the humidity sensitivity is about 2.3%RH·pF-1, hysteresis is about 0.7%F·S, and the repeatability is about 1.9%. Moreover, it gives the measurement uncertainty about 4%, time constance about 0.5 s. In conclusion, the humidity sensor and measurement circuit have good temperature stability, and is suitable for working at a low temperature correctly.