Humidity dependence of electrostatic pick-and-place operation of a micro dielectric particle considering surface conductivity and capillary condensation

Abstract

Relative humidity dependence on electrostatic pick-and-place operation is investigated to improve the reliability of micro-manipulation. The manipulation system consists of three elements: a conductive probe as a manipulator, a conductive plate as a substrate, and a dielectric particle as the target object for manipulation. To pick up/place the particle, a rectangular pulse voltage is applied to the probe. Capillary condensation at the particle-plate interface is theoretically considered to evaluate a detachment voltage (the voltage to detach the particle). Surface conductivity of the particle is theoretically considered to evaluate a detachment time (the time for detaching the particle). Experiments are conducted in relative humidities of 30%, 40%, 50%, and 60% by using a soda-lime glass particle with a diameter of 30 μm. It is clarified that the detachment voltage increases and the detachment time decreases by increasing relative humidity. The particle can be successfully picked up/placed by clarifying the effect of relative humidity on the detachment voltage and the detachment time. This knowledge, relative humidity dependence on electrostatic pick-and-place operation, will contribute to micro-fabrication technology by enhancing adaptability in various atmospheric conditions.