Design And Research Of Wireless Passive Flexible Sensor Based On LC Resonance Principle

In recent years,with the continuous development of electronic skin,intelligent robot and wearable devices,the demand for flexible sensors is increasing.At the same time,in order to deal with many problems such as line aging and battery replacement caused by the use of wired active sensors in special environments,such as confined space and high temperature environment,it is necessary to explore the theory of wireless passive sensors.This paper mainly carries on the relevant theoretical analysis and design of LC resonant wireless passive flexible sensor,and verifies it.The main contents of this paper are as follows:(1)According to the demand of wireless measurement of pressure distribution,an array LC resonance model is proposed and designed.Firstly,a wireless passive flexible pressure sensor model is proposed based on LC resonance principle;According to the material characteristics of flexible substrate polydimethylsiloxane(PDMS),a single parameter simulation optimization sensor method is obtained to obtain the best parameter size value;According to the demand of wireless measurement of pressure distribution,an array LC sensor is proposed,and its lumped circuit model is studied to explore the possibility;The design of array wireless passive flexible pressure sensor is realized by electromagnetic simulation software.The feasibility of the model in wireless measurement of pressure distribution is verified by the offset of two different resonance points.(2)According to the freshness detection requirements of food or drugs in sealed packaging,a design scheme of paper-based wireless passive flexible sensor based on interdigital structure is proposed;Firstly,the theoretical model of interdigital structure is explored;Combined with interdigital structure,LC resonant circuit is designed and integrated on paper substrate;After the lumped circuit analysis of LC resonant circuit based on interdigital structure,the paper-based wireless passive sensor is modeled and simulated by using Circuit Simulation Software Multisim and high-frequency electromagnetic simulation software HFSS respectively.Combined with the parameter scanning function,the feasibility of detecting leaked liquid in confined space is proved;The paper-based wireless passive sensor based on interdigital structure is prepared by screen printing process;Through the test,the sensor is basically consistent with the simulation design,and the correctness of the theoretical design is verified;By simulating the water droplet leakage environment in the confined space,the resonant frequency shift of the sensor is about 14 MHz and the reading distance is about 10 mm,which meets the use requirements.(3)In order to further increase the quality factor of LC resonant circuit and improve the relative sensitivity of LC resonant wireless passive flexible pressure sensor,a flexible pressure sensor with asymmetric double-layer LC resonant structure is designed.By comparing this structure with ordinary single-layer LC resonant structure and symmetrical double-layer structure,the quality factor of LC resonant circuit is improved by about 16,and the relative sensitivity of wireless passive flexible pressure sensor is improved by about 6.6%.Because of its simple structure and long service life,the wireless passive flexible sensor based on LC resonance principle provides a practical implementation scheme to meet the growing demand of wearable electronic devices in the future.