A high-yield method for generating mass-transfer gradients in elastomer microfluidics using impermeable capillaries.

We demonstrated a robust, inexpensive method for fabricating high-throughput gas gradient generation devices which combined classic mass-transfer limited techniques with the versatility of elastomer microfluidics. The method allowed for dozens of replicate mass-transfer gradient experiments per day, including fabrication and assembly of devices. We demonstrated how our devices can be interfaced with microfluidics and how gradient parameters can be varied. In this work, we applied the method to characterize gradients of pH and cell viability generated in mass-transfer limited cultures of HeLa cells and observed the morphology of differentiating C2C12 myoblasts in an oxygen gradient.