High-Output Micro-Machined Electrostatic Actuators

Abstract

This work presents a new class of micromachined electrostatic actuators capable of producing output force and displacement unprecedented for MEMS actuators. The actuators feature submicron high aspect ratio transduction gaps lined up in two-dimensional arrays inspired by the cellular structure of animal muscle tissue. Such arrangement of micro-scale actuator cells, allows addition of force and displacements of a large number of cells (up to 7600 in one array demonstrated), leading to displacements in the hundreds of microns range and several gram-forces of axial force. For 50 µm thick actuators with horizontal dimensions in the 1-4 millimeters range, out of plane displacement of up to 678 µm, bending moment of up to 2.0 µNm i.e. 0.08 N (~8 gram-force) of axial force over the 50 µm by 2 mm cross-sectional area of the actuator (800 kPa of electrostatically generated stress), and energy density (mechanical work output per stroke per volume) up to 1.42 mJ/cm3 have been demonstrated for the actuators.