Thin and large free-standing PDMS membrane by using polystyrene Petri dish

In this technical report, we describe the use of a polystyrene Petri dish to fabricate thin, freestanding polydimethylsiloxane (PDMS) membranes without using a sacrificial layer. We hypothesized that the low work of adhesion between the membrane and the substrate enabled the easy separation of large area thin membranes without extra treatment. To demonstrate this principle, we prepared four substrates with different surface properties: a bare silicon (Si) wafer, a polystyrene (PS) Petri dish, a Si wafer coated with SU-8, and a Si wafer coated with an AZ1512 sacrificial layer. The PDMS had the lowest work of adhesion to the PS Petri dish, which was verified by the Harmonic mean method. Unlike the others three substrates, the thin PDMS membrane on the PS Petri dish could be easily separated without the need for organic solvents and a sacrificial layer. The thickness of produced membrane was measured by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Also, we demonstrated that the high stretching property of thin and large free-standing PDMS membranes enabled the production of arrayed diverse micro-patterned 3D curved structures with a high aspect ratio.