Fabrication and characterization of Parylene C-caulked PDMS for low-permeable microfluidics

This paper proposed a simple and effective fabrication method of Parylene C-caulked PDMS (pcPDMS) for low-permeability required microfluidics applications. Parylene C was deposited into PDMS to caulk the permeable sites and then the over-deposited Parylene C on top of PDMS surface was etched off by oxygen plasma. A buffered hydro-fluoride acid treatment was adopted to recover the over-oxygen-plasma-treated PDMS surface for the following pcPDMS-pcPDMS bonding. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were used to characterize the Parylene C caulked status in the PDMS matrix. Dynamic diffusions of Rhodamine B inside the native PDMS and the pcPDMS were experimentally compared. The preliminary results indicated that the proposed pcPDMS can dramatically suppress the diffusion of small molecules into the PDMS matrix, making it suitable for corresponding microfluidics applications.