Haptic Light-Emitting Diodes: Miniature, Luminous Tactile Actuators

TL;DR

Haptic Light-Emitting Diodes (HLEDs) are compact, luminous actuators that convert pulsed light into tactile forces and displacements, enabling new possibilities in human-machine interaction and tactile displays.

Contribution

This paper introduces HLEDs, a novel combination of light emission and mechanical actuation in a miniature device for tactile feedback applications.

Findings

HLEDs produce forces over 0.4 N and displacements of 0.9 mm.

They respond within 5 to 100 ms at low voltages.

HLEDs are both luminous and capable of tactile actuation.

Abstract

We present Haptic Light-Emitting Diodes (HLEDs), luminous thermopneumatic actuators that directly convert pulsed light into mechanical forces and displacements. Each device packages a miniature surface-mount LED in a gas-filled cavity that contains a low-inertia graphite photoabsorber. The cavity is sealed by an elastic membrane, which functions as a working diaphragm. Brief optical pulses heat the photoabsorber, which heats the gas. The resulting rapid pressure increases generate forces and displacements at the working diaphragm. Millimeter-scale HLEDs produce forces exceeding 0.4 N and displacements of 0.9 mm at low voltages, with 5 to 100 ms response times, making them attractive as actuators providing tactile feedback in human-machine interfaces. Unusually, these actuators are also light-emitting, as a fraction of optical energy is transmitted through the membrane. These photomechanical actuators have many potential applications in tactile displays, human interface engineering, wearable computing, and other areas.