Flexible Multifunctional Platform Based on Piezoelectric Acoustics for Human-Machine Interaction and Environmental Perception

Qian Zhang, Yong Wang, Dongsheng Li, Jin Xie*, Ran Tao, Jingting Luo, Xuewu Dai, Hamdi Torun, Qiang Wu, Wai Pang Ng, Richard Binns, Yongqing Fu*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Flexible human-machine interface shows broad prospects for the next-generation flexible or wearable electronics, in comparisons with currently available bulky and rigid counterparts. However, most of these reported flexible devices (e.g., flexible loudspeakers and microphones) show inferior performance compared to their rigid counterparts, mainly due to the nature of their flexibility. Therefore, it is of great significance to improve their performance by developing and optimizing new materials, structures and design methodology. In this paper, a flexible acoustic platform based on zinc oxide (ZnO) thin film on aluminum foil substrate is developed and optimized, which can be applied as a loudspeaker, a microphone, or an ambient sensor depending on the selection of its excitation frequencies. When used as a speaker, the proposed structure shows a high sound pressure level (SPL) of ~90 dB (with a standard deviation of ~3.6 dB), a low total harmonic distortion of ~1.41%, and a uniform directivity (with a standard deviation of ~4 dB). Its normalized SPL is higher than those of similar devices reported in recent literature. When used as a microphone, the proposed device shows a precision of 98% for speech recognition, and the measured audio signals show a strong similarity to the original audio ones, demonstrating its equivalent performance compared to a rigid commercial microphone. When used as a flexible sensor, this device shows a high temperature coefficient of frequency of -289 ppm/K and a good performance for respiratory monitoring.
Original languageEnglish
JournalMicrosystems and Nanoengineering
Publication statusSubmitted - 19 May 2022

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