PMUT集成Helmholtz谐振腔对测距性能产生的影响分析

Impact Analysis of Integrating Helmholtz Resonators into PMUTs on Ranging Performance

摘要:

压电微机械超声换能器(PMUT)是超声测距领域的重要传感器件,增强PMUT的测距性能对促进工程化应用具有重要意义。基于Helmholtz谐振腔体的吸声和扩声特性,设计了吸收PMUT背部声波的腔体结构及正向扩声的喇叭口结构。实验结果表明,在2 m距离处,集成Helmholtz谐振腔体的PMUT在超声信号幅值上有显著提升,达到321.13 mV,相较于常规贴片薄膜下的腔体结构,信号幅度增加了90.5 mV,增幅为39.2%。此外, 配备Helmholtz共振特性喇叭口的PMUT在同一距离上的信号幅值测量结果为540.72 mV,相较于未配置喇叭口的PMUT,信号幅值增加了162.41 mV,增幅达到42.9%。上述结果表明,将PMUT与Helmholtz谐振腔体的声学特性相结合,对于提升PMUT在超声测距领域的应用具有重要意义。

Abstract:

The piezoelectric micro-machined ultrasonic transducer (PMUT) is an important sensor in the field of ultrasonic ranging. Moreover, enhancing the ranging performance of PMUT is significant for promoting its engi neering applications. This study is based on the sound absorption and amplification characteristics of the Helmholtz resonant cavity and describes the design of a cavity structure that reduces sound wave absorption at the back of the PMUT, as well as a horn structure for forward sound amplification. Experimental results show that at a distance of 2 m, the PMUT integrated with the Helmholtz resonant cavity exhibits a significant increase in ultrasonic signal am plitude, reaching 321.13 mV, which is an increase of 90.5 mV (39.2%), compared with the conventional patch film cavity structure. Furthermore, the PMUT equipped with a horn featuring Helmholtz resonance characteristics measured a signal amplitude of 540.72 mV at the same distance, representing an increase of 162.41 mV (42.9%) compared with the PMUT without the horn. These results indicate that combining the PMUT with the acoustic characteristics of the Helmholtz resonant cavity is of great significance for enhancing the application of PMUT in the field of ultrasonic ranging.