Mask-Free Plasma Patterning for Biocompatible Material Using Atmospheric Pressure Plasma Jet

In this paper, plasma patterning was investigated using an atmospheric pressure plasma jet (APPJ) on biocompatible microdevices constructed using polydimethylsiloxane (PDMS) without the use of mask. This paper aims to identify an alternative approach to the conventional low-pressure plasma patterning with a mask. The reliability of this method was investigated through the hydrophilization of PDMS surfaces for different irradiation times and at different gas flow rates. A parallel electrode configuration with an applied voltage of 20 kV(P-P) was used to generate APPJ. Similar to its behavior under exposure to conventional low-pressure plasmas, the surface of the PDMS became hydrophilic when irradiated using the APPJ. Surface-modifying radicals, such as OH, N-2, and O were identified through optical emission spectroscopy. Hydrophilized areas became larger with a decrease in contact angles when the irradiation time increases. In addition, the APPJ-irradiated PDMS substrate showed the adherence of gene transfer in human-induced pluripotent stem cells (hiPSCs) using fluorescence observation. These results confirmed that mask-free plasma patterning could be achieved using the APPJ.