Enhancement of the surface free energy of PDMS for reversible and leakage-free bonding of PDMS–PS microfluidic cell-culture systems

Polydimethylsiloxane (PDMS) has become one of the most widely used materials in the fabrication of microfluidic systems bonded onto glass substrates, especially for cell biology applications. However, PDMS is often unsuitable for building microfluidic systems onto polystyrene (PS) which is the preferred substrate in most cell-culture protocols. In particular, PS is required for culturing many stem cell and primary cell types. Here, we propose a novel approach to building PDMS–PS microfluidic cell-culture systems, specifically realizing a strong and reversible bonding of PDMS on PS without using chemical agents which can have negative effects on cell viability. Our strategy to strengthen the bonding of PDMS to PS surfaces is to increase the surface free energy (SFE) by adjusting the mixing ratio of PDMS base to curing agent and by treating the surfaces of PDMS and PS with O₂ plasma and annealing. Our results show that using this method for PDMS–PS bonding, we are able to produce reliable reversible and leakage-free PDMS–PS microfluidic cell-culture systems.