电容式Lamb波器件的信号接收方法

Signal reception method of capacitive Lamb wave device

提出了激励和接收均使用电容式叉指换能器(Capacitive Interdigital Transducers,CIDT)的集成化的电容式Lamb波器件。利用电容式叉指换能器直接激励和接收Lamb波非对称模式的方式,解决了机电耦合效率的问题。在分析各种电容检测电路的基础上,针对Lamb波电容式检测的特殊性,选择了直流电路法来进行接收电容变化规律的测量。为说明直流电路法的适用性,设计了波动检测验证实验。实验结果表明:用直流电路法测量得到的声波信号与其理论计算值之间误差仅为2.4%,证明了直流电路法的适用性,解决了目前Lamb波器件的功能材料层的制作工艺均与传统集成电路工艺不兼容的问题。

A Capactive Interdigital Transducer（CIDT） was used in capacitive Lamb wave device to solve the problem that the processes of function layers in most Lamb wave devices were incompatible with classical IC process. In the devices, CIDT were used as both excitation cell and reception cell of Lamb wave, as it was possible to realize the miniaturization. Because of CIDT＇s exciting and receiving the anti-symmetrical modes of Lamb wave directly, the problem of energy-coupling efficiency of transducers was solved. Basing on the analysis of several capacitance detecting circuits, the direct current circuit method was selected to meet the special demands of the device. In order to validate the application feasibility of direct current circuit method, a vibration-detecting experiment was designed. Experimental results show that the error between measurement vibration signal and its theory value is only 2.4%.