Micro-Manipulation and Adhesion Forces

Abstract

In the aim of achieving a task of manipulation of micro-devices with high resolution and accuracy, physical phenomena at the micro-scale were investigated. First studies on magnitude and appearance of forces at this scale let us believe that the use of those forces could be suitable for the fixed task. On the hypothesis that Newton’s laws are applicable at the micro scale, a dynamical model of micro-manipulation, i.e. capture and release of micro-particles, was proposed, simulated and discussed 1; 2 (1; 2). Our goal is to take advantage of sticking effects instead of trying to minimize them. The manipulation will thus be achieved using adhesion forces to capture and release the object. The proposed model integrates all sticking effects taking place at this scale: Van der Waals forces, capillary forces and electrostatic forces as well as deformations at contact 3 (3). First results, obtained by simulation using silicon micro-spheres, show clearly that micro-manipulation using only adhesion forces is possible. We find a “probe initial acceleration window” allowing the manipulation depending on environmental conditions. The experimental set-up for simulation results validation is actually under construction. In this paper we present the last theoretical step before the realization of experiments as well as first experimental results. It is focussed on the determination of the dynamical behavior of a system composed of a piezoelectric actuator and a micro-probe. First studies allowed us to develop dynamical equations of the motion of the free surface of the ceramic and obtain its dimensions ensuring a minimum stress to be generated. The system proposed is then suitable for the task of capture and release of micro-objects. Some experimental adaptation will certainly be necessary to take into account oscillations of the probe for safe and accurate manipulations.