Optimization of Gas Permeability in PDMS Microfluidic Chips for Organ-on-Chip Modeling

Polydimethylsiloxane (PDMS) remains one of the most popular materials for microfluidic chips, but its high gas permeability can lead to the formation of gas bubbles in microchannels, which hampers the reproducibility of experiments in organ-on-a-chip systems. The dependence of the gas permeability of PDMS on the ratio of base to hardener (2.5 : 1, 5 : 1, and 10 : 1) and polymerization temperature (25, 75, and 125°C) was investigated. According to the results obtained, the 5 : 1 ratio at 125°C provides an optimal combination of low gas permeability, fast polymerization, and economical consumption of components. Cytotoxicity testing on BeWo b30 and EA.hy926 cell lines, representing the trophoblast and endothelium in a placenta-on-a-chip model, demonstrated the absence of cytotoxic effects using different ratios of PDMS components, which confirms its safety for cellular experiments.