The effect of impact velocity on interfacial adhesion of contact-mode surface micromachines

Abstract

The effect of impact velocity on the adhesion characteristics of sidewall contact interfaces of dynamic micromachines was studied experimentally using surface micromachines specifically designed for dynamic contact (impact) testing. The evolution of interfacial adhesion with contact cycles was examined for a wide range of impact velocity (frequency). Micromachine lifetime comprised two phases—incubation and surface modification. Shorter lifetime was encountered at higher contact pressure and impact velocity. Permanent adhesion (stiction) due to the interfacial adhesion force exceeding the micromachine restoring force was found to correlate with the product of maximum contact pressure and impact velocity (pressure-velocity limit). Micromachine lifetime decreased nonlinearly with the reciprocal of the pressure-velocity limit. A method for predicting micromachine lifetime was derived based on observed experimental trend. A reversible variation of the adhesion force with impact velocity was observed in the in...