Thin Film Shape Memory Alloy Microactuators

Abstract

Thin film shape memory alloys (SMAs) have the potential to become a primary actuating mechanism for mechanical devices with dimensions in the micron to millimeter range requiring large forces over long displacements. In this paper, the thermo-mechanical behavior of shape memory films is presented, techniques for characterizing Ni-Ti-based shape memory films are evaluated, and design issues for SMA microactuators are discussed. The substrate curvature method is used to investigate the response of Ni-Ti-Cu SMA films, revealing recoverable stresses up to 510 MPa, transformation temperatures above 32°C, and hysteresis widths between near 10°C. Fatigue data shows that for small strains, applied loads up to 350 MPa can be sustained for thousands of cycles.

Barbed micro-spikes for micro-scale biopsy

“…Advances in microelectromechanical (MEMS) technology have led to several attempts to develop micro-scale biopsy tools. Lee et al [5] fabricated a micro-gripper using deposition of shape memory alloy (SMA) on silicon substrates and Krulevitch et al [6,7] reported micro-fabricated instruments for micro-biopsy and precision cutting.…”