Electrical Effect on the Adhesion Force at MEMS Contact Interfaces

A special microdevice was designed and tested to characterize electrical effects on interfacial adhesion in microelectromechanical systems (MEMS). The adhesion force was measured as a function of the voltage applied across the contact interface. An increase in the adhesion force was attributed to electrostatic attraction resulting from trapped charges. A thermal effect at contacting asperities enhanced the adhesion force significantly. At a critical voltage, microwelding at asperity contacts caused the surfaces to adhere strongly to each other. The adhered device could not be released within its operation limits, indicating the development of a very high adhesion force.