电容式湿度传感器结构优化

Structural optimization of capacitive humidity sensor

对圆筒形电容式湿度传感器进行合理的结构优化.依次改变极板的直径、长度、厚度、间距、个数等,利用有限元分析软件模拟上述条件下电容器极板的场强的分布,找到场强随这些参数的变化规律.分析结果发现,单层极板呈现出明显的边缘效应;随直径增大,边缘场强与内部场强的比值增大;极板越薄,边缘场强越小;适当加大极板长度,可减缓边缘场强增加的速率,但效果有限.多层极板,随间距增大,边缘场强与内部场强的比值增大,但总电容变化量减小;极板的间距应适当选取.对于多层极板,中间极板的场强有相互抵消的现象,故而可以适当减小中间极板的间距,以增加极板的个数,对测量有利.推荐了最佳尺寸.

Do reasonable structural optimization for a coaxial cylindrical capacitive humidity sensor. First, change the diameter, length, thickness, spacing, number of the plates in turn. Then, use the finite element analysis software to simulate the electric field intensity distribution of the capacitor under the above condition, find how electric field intensity changes with these parameters and recommend the best size. Results of the analysis are that single plate has obvious edge effects ; the ratio of edge field intensity to internal field intensity increases with the enlarging of diameter; the thinner the plate, the smaller the edge field intensity ; increasing the length of the plate can slow down the increase rate of the electric filed, but the effect is limited. For multi-plate, with the spacing increasing, the ratio of the edge filed intensity to the internal field intensity increases, but total capacity change decreases. The distance between plates should be properly selected. For multi-plate, the middle plate field has offset effect, therefore, the spacing between the plates can be appropriately reduced to increase the number of the plates, which helps the measurement. The best size is recommended.