Material Characterization and Transfer of Large-Area Ultra-Thin Polydimethylsiloxane Membranes

Fabrication of ultra-thin (1-20-μm thickness) polydimethylsiloxane (PDMS) films is enabled with a hexane dilution process and an underlying gelatin release layer. The release and transfer of these films over large areas (>5 cm) allows measurement of the thickness-dependent and process-dependent mechanical properties of ultra-thin PDMS membranes, reported for the first time. The effective Young's modulus of 1-μm-thick PDMS, measured by bulge testing, is approximately ten times larger than that of 0.5-mm-thick material, following a continuous power-law relationship over the entire thickness range. Mesh-patterned metal electrodes of 2-μm minimum feature size are embedded in selected membranes. Metal evaporation and subsequent reactive ion etch patterning on PDMS increases its Young's modulus due to the increase in cross-link formation and hardening of the surface. The results are meaningful in design and fabrication of soft electronics, microsensors, microvalves, and micropumps.