MEMS微流量检测中寄生电容干扰的抑制方法

Method of Eliminating Parasitic Capacitances in Micro Flow Measurement of MEMS Devices

MEMS器件微流量流速检测中会受到寄生电容的严重干扰,针对两腔键合的压电驱动硅基微流量传感结构,通过对该结构中Si-Pt平行板电容分析及其对交变方波驱动的输出响应分析,确定了寄生电容产生于两腔键合处的上腔基质硅与检测热敏铂丝之间,提出了通过压电驱动电极的适当连接抑制寄生电容干扰的有效方法。

Parasitic capacitances sometimes tend to be a undesired signal which interfere the output of useful signal during the micro flow measuring of MEMES devices. The generation and the elimination of parasitic capacitances in bicavitary bonding microsensor structure actuated by PZT were analyzed. The theory expression of parasitic capacitance was derived according to the superposition principle and the differentiating circuit theorem. And the response waveform of simulating parasitic capacitance was quite similar to that of measuring. Thus it was determined that the parasitic capacitances were induced between the silicon substrate and the Pt wire where those two cavities were bonded. The elimination method of such parasitic capacitances is presented and proved to be effective by experimental results.