Inkjet printed SU-8 hemispherical microcapsules and silicon chip embedding

Abstract

Planar lithography techniques are not effective for precise fabrication of microdevices with hemispherical shapes. Drop-on-demand (DOD) inkjet printing (IJP) of photo-curable ink is a more appropriate fabrication approach as it takes advantage of the surface tension as well as of the delivery of a well-defined ink volume. Described is a DOD IJP technique onto geometrically-patterned silicon substrates enabling the controlled fabrication of SU-8 hemispherical microcapsules. Open half capsules of 100 µm in diameter with inner cavity volumes of 5, 20 and 45 pl with a printing yield above 96% are demonstrated. The same technique is directly adapted to the fabrication of microcapsules embedding silicon microchips. The reported findings open new paths for controlled encapsulation of liquids into smart microsystems.

Self-assembly of micro/nanosystems across scales and interfaces

“…We started with wafer-level, inkjet printing (IJP)-based fabrication of SU-8 hemispherical caps which could either host on their flat side hollow cavities of arbitrary geometrical shape or encapsulate thin silicon chips [37]. Hemispheres, easily fabricated by IJP on pedestals, are geometrically well conducive to pair-wise assembly [19].…”

“…As an alternative to capillary self-folding and sealing of polyhedral microvoxels [13], fluidic SA affords simpler fabrication still compatible with the embedding of functionalities within the microcapsules [37], although the process is limited to work in polar liquids. Liquid release may be triggered by bioerosion when the capsules are fabricated with biodegradable polymers, such as polylactic acid.…”

Inkjet Printing of High Aspect Ratio Superparamagnetic SU-8 Microstructures with Preferential Magnetic Directions

“…Technically, confining a liquid drop by pinning its contact line on a convex edge can be done with edges whose minimum heights are as low as the length range of the polymer chain [24,25]. Yet the confinement of inkjet printed micro drops has been so far described only on much higher pedestals, 5 μm [26]. Confinement on lower edges may be useful for a lot of applications, for example in micro-optics.…”

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

“…Computing and sensing capabilities can be embedded in such barely visible cargos [4], whose collective potential is tackled in large distributed swarms [3]. In this perspective, optimal and cost-effective resource utilization require massive parallelism and scalability for both fabrication and assembly of microcapsules.…”

“…As an alternative to capillary self-folding and sealing of polyhedral microcontainers [10], our SA method affords a simpler fabrication process still compatible with the embedding of functionalities (e.g. microchip [4]) within the microcapsules.…”