Wearable multifunctional piezoelectric MEMS device for motion monitoring, health warning, and earphone

Abstract To solve the problem of a single function encountered by wearable electronic devices, a multifunctional wearable piezoelectric MEMS device is presented, which performs motion monitoring and disease and health warning according to respiratory frequency, functions as an earphone based on the inverse piezoelectric effect of the PZT film. The rigid-flexible coupling sealed vibration membrane allows the piezoelectric MEMS device to eliminate acoustic loss or avoid airflow loss. By placing the device in a simple wearable mask, the inactive, walking, and running states may be possible to be recognized and monitored through respiratory frequency. In the inactive state, the device can identify diseases when abnormally fast or slow respiration occurs. By placing the device in the surgical mask when going out, an early warning of something affecting lung health can be obtained by excessive respiration frequency when wearing the mask for too long. Moreover, the device can also be utilized as an earphone. Higher than 55 dB SPL can be obtained in the full frequency range of the human ear under 2 V, meeting the basic needs of people's hearing. This simple strategy represents a significant step toward future applications of the wearable piezoelectric MEMS device due to its portability, multifunctioning, convenience, and mass production.