A Flexible Piezoelectret Actuator/Sensor Patch for Mechanical Human-Machine Interfaces

Flexible and wearable devices with the capabilities of both detecting and generating mechanical stimulations are critical for applications in human-machine interfaces, such as augmented reality (AR) and virtual reality (VR). Herein, a flexible patch based on a sandwiched piezoelectret structure is demonstrated to have a high equivalent piezoelectric coefficient of d₃₃ at 4050 pC/N to selectively perform either the actuating or sensing function. As an actuator, mechanical vibrations with a peak output force of more than 20 mN have been produced, similar to those from the vibration mode of a modern cell phone, and can be easily sensed by human skin. As a sensor, both the pressure detection limit of 1.84 Pa for sensing resolution and excellent stability of less than 1% variations in 6000 cycles have been achieved. The design principle together with the sensing and driving characteristics can be further developed and extended to other soft matters and flexible devices.