Strategy of pickup and release of micro-object by approach angle in geometrical and mechanical conditions

Abstract

This paper discusses a micro manipulation considering that an approach angle on pickup affects adhesion and mechanical balance on release by using two needle-shaped end-effectors. In micro-scale, adhesion is generated by capillary, van der Waals and electrostatic besides gravity. Accurate and repeatable pick-and-release/place of micro sized objects is a longstanding challenge due to the strong adhesion in micro manipulation. We first introduce a strategy of pickup and release of a micro sphere. The strategy features in that the approach angle on pickup decides release by two conditions: one is geometrical condition between the sphere and a tip of end-effector, and the another is mechanical condition by forces (adhesion, gravity and friction) to the sphere from the tip and a substrate. To confirm the efficacy of the strategy, the micromanipulation tests with different approach angles have been conducted. Finally, we show the experimental results by pickup and release of spherical glass beads and not spherical pollens, for confirming the validity of the proposed strategy as a novel manipulation method.