Liquid-filled sealed MEMS capsules fabricated by fluidic self-assembly

We present a new method to encapsulate functional liquids into sealed MEMS capsules by fluidic self-assembly. Self-assembly of 200 μm SU-8 cargos and picoliter liquid co-encapsulation are driven by the interplay of global fluidic drag and short-range capillary forces. The latter ensues from the localized surface-selective precipitation of a photopolymerizable adhesive onto the capsules´ rim. Assembly yield higher than 50% is achieved, and can be improved by optimized agitation and shape matching. The method is massively parallel, scalable and compatible with batch MEMS fabrication. It can address a variety of applications, including distributed MEMS, cell encapsulation and drug delivery.