Self-transformed parallel structures in strain sensitive Au thin film micropattern embedded on soft elastomer

Abstract

This work presents a self transformed method of ordering random buckles in thin metal film fabricated on soft elastomeric film for reliable MEMS devices. Detailed modeling of thin metal film buckling and buckle manipulative stresses associated with the self transformed film is investigated. In this study, a thin metal Au film deposited with dc sputtering is used as a strain sensing film on an elastomeric of polydimethylsiloxane (PDMS) film. To increase the adhesion between the metal film and underlying PDMS film, a self-assembled molecular adhesive layer of (3-mercaptopropyl)trimethoxysilane (MPTMS) has been introduced. The random buckles developed in the Au film were successively oriented without using any ridge surface and prestrain PDMS film for the first time. The strain response study of the Au thin-film resistors of different thicknesses has been characterized for determining the normalized variation of resistance for linear operation. The experimental result showed that the Au thin film resistor on PDMS has high strain sensitivity compared to Au film on Si. The microscopic study of the Au thin film resistor confirmed that the observed high resistance change is due to the micro/nanocracks near grain boundaries on the thin Au film. This study is beneficial for ordering random buckles in hybrid thin-film microstructure on soft elastomer material and fabricating high strain sensitive MEMS devices.