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Liquid Crystal Elastomers (LCEs) are promising candidates for soft-matter-based actuators for MEMS devices. They are loosely crosslinked polymer networks that show high strain rates. The ordering of embedded liquid crystals defines their actuation profile, and these actuators can demonstrate complex actuating mechanisms such as radial contraction and helical bending. However, their applications are limited in MEMS technology because of limited fabrication processes compatible with the actuator's fabrication. We present a new method to structure the LCE actuators with spatially structured light compatible with MEMS fabrication processes. Fabrication of 50-100 μm thick actuators is done with the standard glass-cell filling process via capillary forces. As material polymerization is light-initiated, material structuring is achieved by selective polymerization with UV light. Then, after developing the material, the polymerized LCE is bonded to a secondary substrate via a stamp-and-stick technique. A digital micromirror based (DMD) based projection setup was built to project the computer-generated arbitrary patterns on the substrate. This setup allows spatial structuring of the light, thereby enabling the pixel-by-pixel selective polymerization of the LCE actuators. This so-called maskless photolithography of the material enables the patterning of LCE actuators without any printed mask, hence improving the fabrication of the LCE-based MEMS devices. This process ow is automated to easily scale up the fabrication process to the 100mm wafer level. |
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