Multi-layering of SU-8 exhibits distinct geometrical transitions from circular to planarized profiles

Abstract

The negative tone photoresist SU-8 permits the creation of micrometer-scale structures by optical lithography. It is also the most used photoresist in soft lithography for the fast-prototyping of microfluidic devices. Despite its importance, the effect of capillary forces on SU-8 multi-layering onto topographical features has not been thoroughly studied. In particular, the profile of the added layer has not been examined in detail. The overlaying process exhibits a set of distinct behaviors, or regimes, depending on the relative thickness of the overlay and the underlying rectangular pattern. We demonstrate how capillary effects control the profile of multi-layer microchannels in a predictable manner. We derive a simple static model to describe the evolution of the overlay as a function of dimensionless geometric parameters. Our study provides a critical understanding of the parameters that govern multi-layer spin coating.

Magnetically Functionalized Hydrogels for High‐Throughput Genomic Applications

“…[ 19 ] An established protocol to create a double‐layer mold was used. [ 20 ] The microfluidic circuits using the AutoCAD software (AutoDesk, San Francisco, CA, USA) and had them printed onto mylar masks (CAD/Art services, Bandon, OR, USA) were designed. A negative photoresist (SU‐8, Kayaku Advanced Materials, Westborough, MA, USA) onto 3″ silicon wafers was spincoated.…”

Robust and rapid partitioning in thermoplastic

“…The branched inlet and outlet were patterned onto a second 80 μm deep layer using an established protocol. 19 The mold was treated with a vapor of fluorinated silane overnight in a vacuum chamber. A 10 : 1 (w/w) PDMS secondary mold was created by casting the silicon SU8 hybrid mold.…”