集成铁氧体的LC应变传感器的设计及测试

Design and test of LC wireless passive strain sensor integrated with ferrite

针对金属环境下采用LC无线无源应变传感器出现电磁信号传输失效的问题,在传感器背面集成铁氧体材料,其原理是通过抑制电磁波在金属表面的涡流效应产生的感应电动势,实现在金属环境下的电磁信号耦合测试。通过HFSS软件进行仿真验证,在金属环境下LC无线无源传感器信号失效;在传感器基底背部集成铁氧体后,通过扫频得出铁氧体可以在金属环境下实现LC传感器的电磁信号传输。对铁氧体的厚度进行参数优化,最佳厚度为0.32 mm。搭建等强度悬臂梁测试平台,结果表明,金属环境下LC传感器可以通过铁氧体实现抗金属环境干扰,频率为37.7 MHz时,LC无线无源测试系统可以很好地实现信号传输,对应的S_(11)值为-25.6 dB。对悬臂梁施加外力使其发生应变,传感器在0~1300με的应变范围内灵敏度为61.54 Hz/με。测试结果表明,铁氧体有利于实现金属环境下的LC无线无源传感器应变测试。

To solve the problem of electromagnetic signal transmission failure caused by LC wireless passive strain sensor in metal environment,ferrite material is integrated on the back of the sensor.The principle is to realize electromagnetic signal coupling test in metal environment by suppressing induced electromotive force generated by eddy current effect of electromagnetic wave on metal surface.Through simulation verification of HFSS software,LC wireless passive sensor signal failure in metal environment.After adding ferrite to the back of sensor base,it is concluded that ferrite can realize electromagnetic signal transmission of LC sensor in metal environment through frequency sweep.The optimum thickness of ferrite is 0.32 mm.The test platform of equal strength cantilever beam was built.The results show that LC sensor can resist metal environment interference through ferrite in metal environment.When the frequency is 37.7 MHz,LC wireless passive test system can realize signal transmission well,and the corresponding S_(11) value is−25.6 dB.The sensitivity of the sensor is 61.54 Hz/μεin the strain range from 0 to 1300με.The test results show that ferrite is beneficial to realize the strain measurement of LC wireless passive sensor in metal environment.