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

TLDR

Flexible wearable devices that can both detect and generate mechanical stimulation are essential for human–machine interfaces such as AR and VR. This work demonstrates a flexible piezoelectret patch with a high piezoelectric coefficient (d33 = 4050 pC/N) that can selectively act as an actuator or sensor, and proposes extending this design to other soft/flexible devices. The patch employs a sandwiched piezoelectret structure that achieves the high d33 value, enabling selective actuation or sensing. As an actuator, it delivers peak forces over 20 mN comparable to a cell‑phone vibration and is easily sensed by skin; as a sensor, it achieves a 1.84 Pa pressure detection limit and maintains stability within 1 % over 6000 cycles.

Abstract

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.