Electrostatic/electromagnetic gripper for micro-assembly

In this paper, an electrostatic/electromagnetic gripper is used to pick up copper LIGA parts. The experimental results show that the gripper can reliably pick up a 4 mm diameter, 100-micron thick part when it is within 80 microns of the part and a 120-volt potential is applied to the electrostatic pads. Unfortunately, there was a 38 percent probability that the part will stick to the gripper when the voltage is returned to zero. This sticking effect is believed to be caused by residual electrostatic, van der Waal, and surface tension forces. However, the probability of sticking was reduced to 6 percent when electromagnetic coils were added to the gripper design.