Translatory and Bending Micro Magnetostrictive Actuator using Iron–Gallium Alloys (Galfenol): A New Actuation Approach for Microrobots

Abstract

There is strong demand for microactuators in medical and industrial fields. For example, minimally invasive surgery has been progressing, and a series of microactuators useful for positioning, grasping and cutting in a narrow space are required. For this purpose, we are investigating micro magnetostrictive actuators using iron–gallium alloy (Galfenol). Galfenol is an iron-based magnetostrictive material with magnetostriction greater than 200 p.p.m., a high relative permeability μ r greater than 100 and a Young's modulus of around 70 GPa. This material is machinable by conventional cutting techniques, and can operate under tensile, bending and impact loads without any degradation in performance. Therefore, a microactuator using Galfenol has advantages over conventional actuators such as electrical motors and piezoelectric actuators in terms of design simplicity, low drive voltage requirements and high robustness. In this paper, we describe two types of actuators consisting of a U-shape core of Galfenol — one providing 1 longitudinal d.o.f. and 2-d.o.f. bending deformation, and the other propelling by a friction drive. These actuators are simple and small, and easily integrated into actuation parts of microrobots.