Study On Wireless And Passive Sensors Based On Lamb Wave Resonators

Lamb wave resonator(LWR)is a kind of piezoelectric resonant sensors,which has been utilized in chemical sensing and biological sensing thanks to it's micrometer-scaled sizes and CMOS-compatibility.In a conventional sensing situation,piezoelectric resonant sensors require a wired connection to the readout system.However,when it comes to experiments that require medical sensing inside the living beings or under harsh environmental conditions,the conventional sensing methods are not competent.On the contrary,wireless and passive sensors are more suitable under those conditions.So researchers pay much more attention on wireless and passive sensors,which has been developed rapidly.However,there is little studies based on wireless and passive piezoelectric resonant sensors.So,this paper focuses on the defects of the current wireless piezoelectric resonator and proposes a novel method for wireless and passive detection of piezoelectric resonators.In this paper,the theory of near field inductive coupling for wireless and passive communication is introduced,which provides a theoretical basis for the design of planar inductors.Then,the working principle and manufacturing process of AlN LWR are explained.Based on the equivalent circuit model of inductive coupling and piezoelectric resonator,a new equivalent circuit is proposed for the simulation and design of wireless passive piezoelectric resonators.In addition,using the equivalent model and related simulation software,we analyzed the effect of different inductance value on the piezoelectric resonator.Besides the most suitable value of coupling inductances through this process is determined.Based on that,structures of coupling inductances for wireless and passive communication is designed and analyzed.Also,we provide an experimental platform for testing and analyzing the performance of the wireless and passive LWR.And,the responses of wireless resonator under ethanol gas with different concentrations and infrared irradiation with different power density are recorded.Finally,A wireless and passive LWRs array is proposed.The resonators with different frequencies are connected with the same coupling coil in parallel,and the potential of the wireless sensor array in sensing application is verified by a gas sensing experiment.