Freestanding smooth micron-scale polydimethylsiloxane (PDMS) membranes by thermal imprinting

Abstract

We report on a novel fabrication process based on thermal imprinting for the formation of micron-scale, freestanding, dielectric layers of poly(dimethylsiloxane). This technique is the basis for three-dimensional elastomeric membrane micro-electro-mechanical system applications where the structural material is part of the actuator and the lateral expansion is by vertically applied bias. We have fabricated freestanding smooth defect-free membranes with thicknesses in the range of 0.4–4.8 μm and with diameters of centimeters order of magnitude. A curve was plotted to calibrate the thickness of the elastomer layer to the pressure of the imprint. The adhesion between the polymer and the silicon (Si) chip's surface was reduced by the deposition of a hydrophobic dodecyl-trichlorosilane monolayer on the chips prior to imprinting. The ability to detach the membrane from the chips after imprinting is critical for the production of layers that are freestanding. Additionally, we demonstrate the feasibility of patterning the membranes at the time of imprinting to create freestanding patterned micron-scale membranes. A simple device made up of a freestanding circular membrane with electrodes on the circumference demonstrating the application of the method is presented here. The device's electromechanical characteristics are presented as well.