Facile fabrication of microperforated membranes with re-useable SU-8 molds for organs-on-chips

Microperforated membranes are essential components of various organ-on-a-chip (OOC) barrier models devel-
oped to study transport of molecular compounds and cells across cell layers in e.g. the intestine and blood-brain
barrier. These OOC membranes have two functions: 1) to support growth of cells on one or both sides, and 2) to
act as a filter-like barrier to separate adjacent compartments. Thin, microperforated poly(dimethylsiloxane)
(PDMS) membranes can be fabricated by micromolding from silicon molds comprising arrays of micropillars for
the formation of micropores. However, these molds are made by deep reactive ion etching (DRIE) and are
expensive to fabricate. We describe the micromolding of thin PDMS membranes with easier-to-make, SU-8 epoxy
photoresist molds. With a multilayer, SU-8, pillar microarray mold, massively parallel arrays of micropores can
be formed in a thin layer of PDMS, resulting in a flexible barrier membrane that can be easily incorporated and
sealed between other layers making up the OOC device. The membranes we describe here have a 30-μm
thickness, with 12-μm-diameter circular pores arranged at a 100-μm pitch in a square array. We show application
of these membranes in gut-on-a-chip devices, and expect that the reported fabrication strategy will also be
suitable for other membrane dimensions