Fabrication and evaluation of freestanding stretchable nanosheet for optical MEMS application

We developed a stretchable freestanding ultra-thin sheet composed by poly(styrene-butadiene-styrene) (SBS) and evaluated its optomechanical properties. The freestanding SBS sheet with a thickness of 675 nm was formed above a through hole of a PDMS sheet. Deflection of the freestanding sheet with a size of 10.4 mm × 10.4 mm was found to be 50 nm by optical surface profiler. In evaluation of the sheet stretch measured by reflection spectra of a thin-film interference peak, SBS nanosheet revealed about 38% of elastic strain. This result demonstrated that the SBS nanosheet is stretchable even though its thickness is one order magnitude of thinner than PDMS.