Fabrication of Biomimetic Cell Culture Membranes Using Robust and Reusable Nickel Micropillar Molds

In the practical application of organ-on-a-chip, mass production technology for flexible porous membranes is an essential element for mimicking the basement membrane of the body. Porous PDMS membrane is a promising material due to its high optical transparency, flexibility, and biocompatibility. However, the fabrication process is complex and costly. Even with soft lithography, a relatively straightforward method, there is a risk that the negative resist pillars used as molds peeling off from the substrate in mass production. In this study, we propose a novel mass production method for fabricating porous PDMS membranes using high-strength nickel (Ni) micropillars as molds by combining photolithography and electroforming technologies. The unibody structure of Ni micropillars ensures high reliability and provides a semi-permanent mold without degradation or detachment. We successfully fabricated two types of Ni micropillars and subsequently formed their corresponding porous PDMS membranes (D (diameter) = 8 μm, P (pitch) = 30 μm, and D = 10 μm, P = 20 μm). The porous PDMS membrane showed non-inferiority to the control group in terms of viability when cultured with human vascular endothelial cells. Furthermore, we showed that the porous PDMS membrane can be used to evaluate the vascular permeability of nanoparticles.