During the early 1960s electrostatic forces were investigated as part of the NASA space programm for clamping objects to metal satellite surfaces. Additional applications included the holding of paper in plotters and electrostatic chucks for the retention of semiconductor wafers during epitaxial processing. In the 1980s the same methods were adopted for use in robot grippers intended for the handling of flexible materials such as polymer sheets, textile fabrics, carbon and glass fibre etc.

Recent research has focused on the use of electroadhesion for the prehension of minute optical components such as lenses, prisms, mirrors and filters. Such delicate components cannot so easily be handled using conventional impactive techniques where the danger of damage is too great. The picture below shows a microgripper lifting a small concave lens a few millimetres in diameter.

Taking the technology a step further lead to the development of a microgripper capable of handling components of less than 1 mm in diameter, as shown in the next picture where a 500 um half spherical lens can be seen on the gripper surface. With a voltage of a few hundred volts, the current is in the low microamp region. The components may be lifted and deposited on an X-Y table, the Z axis being a piezoelectric bimorph element.

Convential electroadhesive grippers often suffer from the problem of delayed object release owing to residual charge, surface tension forces etc. Using special controlled release techniques, this gripping method may be used to provide fast, accurate and reliable object release. (UK patent GB9921403.3)

This research was carried out with 100% industrial funding from International Phoretics (UK) and Ion-Lite Corp. (USA).