Untethered Soft Thin-Film Motor for Portable Human-Machine Interface

Flexible and lightweight actuators have demonstrated various potential applications in wearable devices, health monitoring systems, and haptic feedback devices. Compared with rigid motors, flexible motors can directly interface with soft human tissue. This paper introduces a soft lightweight thin-film motor driven by electrostatic forces, which can achieve effective vibration control through optimized structural design and material selection. With an overall thickness of approximately <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$350\ \mu \mathrm{m}$</tex>, the thin-film motor can produce a vibration displacement of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$100\ \mu \mathrm{m}$</tex> under an applied square wave voltage of 280 V at 100 Hz. A mathematical model is proposed to predict the displacement of the thin-film motor at different applied voltages. A miniaturized wireless control circuit has been designed, and integrated with the thin-film motor. The entire untethered flexible motor system significantly enhances its portability. This research demonstrates the effectiveness of the thin-film motor and highlights its potential in wearable devices and interactive systems.