Modeling and Simulation of a Bio-Mimetic MEMS Actuator With Self-Sensing for Thrombus Retrieving

Abstract

A new bio-mimetic MEMS actuator device with self-sensing used for thrombus retrieving is presented. The device contains four laterally apposed triangular teeth forming a square which is inspired by the jaws of an earthworm that has radial teeth around a circular mouth. Each tooth is fixed only at the perimeter of the square and consists of several layers including piezoelectric material (PZT) layers, electrode layers (Ti/Pt) and diffusion barrier layers. Due to mismatch of thermal expansion coefficients of different layers, each of the four triangular teeth would initially curve up after the micro fabrication opening the “jaws” of the device. The teeth can then be driven to a closed position by applying an electric field to the PZT layers. The self-sensing method of the piezoelectric device is used for detecting the external force exerted by the teeth and feedback control system in this bio-mimetic MEMS actuator device. The mathematic model which can be used to calculate and control the residual stress causing the curvature of these teeth is discussed. Additionally, residual stress coupled with the piezoelectric stress and external force is also considered. The materials and thickness are optimized by using the linear model developed in this paper. Moreover, with this mathematic model and geometry of these teeth, the motion tracks driven by two different modes are simulated.