Enhancing dry adhesion of polymeric micropatterns by electric fields

Micropatterned dry adhesives rely mainly on van der Waals interactions. In this paper, we explore the adhesion strength increase that can be achieved by superimposing an electrostatic field through interdigitated subsurface electrodes. Micropatterns were produced by replica molding in silicone. The adhesion forces were characterized systematically by means of experiments and numerical modeling. The force increased with the square of the applied voltage for electric fields up to 800 V. For larger fields, a less-than-quadratic scaling was observed, which is likely due to a small, field-dependent electrical conductivity of the materials involved. The additional adhesion force was found to be up to twice the field-free adhesion. The results suggest an alternative method for the controlled handling of fragile or miniaturized objects.