Low Cost Microwave Plasma Generation for the Irreversible Sealing of PDMS Microfluidic Devices-

Sealing of Poly-dimethylsiloxane (PDMS) microdevices onto glass or PDMS substrate is an important step to achieve hydrophillicity and form closed microfluidic channels. PDMS is very hydrophobic and to enhance hydrophilic behavior, PDMS substrates can be treated using a UVO or plasma cleaner. Commercial plasma cleaners are expensive (~4K) and often rely on clean air or oxygen to generate the required plasma. Our goal was to develop a cheaper working plasma generation system for less than $100, using parts easily obtainable from an average hardware store, and with no specialized tools. A low cost room-air microwave plasma generator was fabricated using a 400W, 2450MHz Sharp brand “Household Microwave Oven” for the purpose of exploring the possibility of irreversible sealing onto glass with minimal budgetary commitment. Irreversible sealing was observed via peel testing. Goniometry testing to verify hydrophilicity was performed on PDMS substrates treated with the room-air microwave plasma system developed here, and was compared with the commercially available Harrick Plasma (PDC-32G) plasma cleaner.