Surface characterization of plasma-treated PDMS-PCTE-PDMS microfluidic chip for particle separation

Integrating membranes into microfluidic chips expands applications in many fields. A key challenge in fabrication of membrane-integrated microfluidic chips is the effective bonding of membrane and the substrate. Herein, the surface of polycarbonate track-etched membrane was modified by oxygen plasma treatment to enhance the bonding strength. Contact angle measurements confirmed the wettability of the membrane surfaces was significantly improved by plasma treatment. X-ray photoelectron spectroscopy and scanning electron microscopy analyses revealed increased oxygen incorporation onto the surface of the membranes and a linear increase in the membrane's pore size with treatment time. Two models of modification were proposed in molecular dynamics simulations to study the wetting mechanism of plasma-treat membrane at a micro scale. Burst pressure test and particle separation experiment were conducted to study the optimal parameters for plasma treatment and validate the performance of microfluidic chip. Oxygen plasma treatment effectively enhances the hydrophilicity of the membrane, generates robust intermolecular interactions and strengthens its bonding strength with the substrate.