A New 1-mg Fast Unimorph SMA-Based Actuator for Microrobotics

TL;DR

This paper introduces a compact, fast, and lightweight unimorph SMA-based actuator for microrobotics, enabling the creation of highly capable micro-robots with impressive speed, weight, and functional performance.

Contribution

The paper presents a novel SMA-driven unimorph actuator with passive-capillary alignment, enabling the development of ultra-lightweight, high-frequency, and high-load microrobots.

Findings

MiniBug is the lightest fully-functional crawling microrobot of its type.

WaterStrider is the lightest controllable SMA-driven water-surface-tension crawler.

The actuator achieves operation frequencies up to 40 Hz and lifts 155 times its weight.

Abstract

We present a new unimorph actuator for micro-robotics, which is driven by thin shape-memory alloy (SMA) wires. Using a passive-capillary-alignment technique and existing SMA-microsystem fabrication methods, we developed an actuator that is 7 mm long, has a volume of 0.45 mm^3, weighs 0.96 mg, and can achieve operation frequencies of up to 40 Hz as well as lift 155 times its own weight. To demonstrate the capabilities of the proposed actuator, we created an 8-mg crawler, the MiniBug, and a bioinspired 56-mg controllable water-surface-tension crawler, the WaterStrider. The MiniBug is 8.5 mm long, can locomote at speeds as high as 0.76 BL/s (body-lengths per second), and is the lightest fully-functional crawling microrobot of its type ever created. The WaterStrider is 22 mm long, and can locomote at speeds of up to 0.28 BL/s as well as execute turning maneuvers at angular rates on the order of 0.144 rad/s. The WaterStrider is the lightest controllable SMA-driven water-surface-tension crawler developed to date.