Benchtop Polymer MEMS

Loctite photopatternable adhesives 3108, 3340, and 3525 are introduced for microelectromechanical systems (MEMS) applications. These materials are patterned within minutes by exposure to ultraviolet (UV) light followed by rinsing with a solvent; no further processing is required. Because the uncured fluid is relatively insensitive to room light, this can be done on any lab bench without the requirement for a clean room. The materials can be spin-coated to obtain films, or cast between spacers for layers up to 1 cm thick, and the cured polymers range from elastomeric to rigid. These adhesives are of interest for rapid, inexpensive fabrication of relatively low-resolution features (tens to hundreds of micrometers) by photocuring. They can alternatively be molded, like polydimethylsiloxane (PDMS), to achieve high resolution, as well as irreversibly bonded after an O₂plasma treatment. In addition, like SU8, they can be used as molds for patterning PDMS. Initial characterization of resolution, swelling, and biocompatibility were performed. One of the polymers, 3340, can be used for packaging bioMEMS-on-complementary-metal–oxide-semiconductor (CMOS) chips, exploiting its biocompatibility and its photopatternability at thicknesses of 1500$mu$m to cover the bond wires while exposing the chip surface. As further demonstrations of the versatility of these materials, multilevel, interconnected channel structures were fabricated with a gelatin sacrificial layer, and magnetic films were prepared, since the polymers remain patternable even with additives.1535