Suspended SU-8 structures for monolithic microfluidic channels

SU-8 photoresist is commonly used in the field of microfabrication as structural material or for molding of microfluidic devices. One major limitation, however, is the difficulty to process partially freestanding SU-8 structures or monolithic closed cavities and channels on-chip

Fabrication process of a suspended SU-8 structure for a monolithic closed SU-8 microchannel. a A standard SU-8 layer is spin-coated on a silicon wafer, followed by a soft-bake, exposure to define the channel walls (mask 1) and a post-bake. b A second layer using a modified high-UV-absorption SU-8 is spin-coated, soft-baked, and exposed to define the roof of the microchannel (mask 2).c Exposure through mask 1 is applied before the post-bake to improve the adhesion between the two SU-8 layers. d The SU-8 double layer is developed to release the microchannel

Y. Moser • R. Forti • S. Jiguet • T. Lehnert • M. A. M. Gij

Microfluid Nanofluid (2011) 10:219–224