6.021/PDMS

How to make a PDMS chip
Material used (both from Dow Corning):
 * Sylgard 184 silicone elastomer curing agent
 * Sylgard 184 silicone elastomer base


 * 1) by weight, make mixture base:curing agent of 10:1. For 6 inch wafer, 70g-77g total gives good height to avoid hitting objective on microscope.
 * 2) mix gently with glass rod for 10 min
 * 3) put mixture into vacuum chamber to get rid of air bubbles inside mixture (1-2 hours)
 * 4) * Turning on and off the vacuum also helps in eliminating bubbles
 * 5) With alumninum foil, create a container around the wafer
 * 6) Pour mixture onto the master wafer (gently without generating too many air bubbles)
 * 7) If air bubbles are present, blow on it with a nitrogen gun
 * 8) Put wafer into over @ 65C for at least 2 hours (overnight preferred)
 * 9) Cut carefully the foil off the wafer and pull off the PDMS from the wafer. It is easiest to start at the bottom of the wafer.
 * 10) Cut the chips out of the PDMS
 * 11) Avoid touching the surface to be bonded (the side with the microfluidic channels, i.e. the bottom) with fingers

Plasma bonding
To attach the PDMS to glass:
 * 1) Clean the glass with soap, DI water, isopropanol, then dry with nitrogen
 * 2) Use scotch tape to remove any particles that may be on the PDMS chip. Just stick some tape on to the surface and pull. Repeat.
 * 3) Turn the power on the plasma machine
 * 4) Put samples in the machine with the bonding face up
 * 5) Make sure RF power is in off position
 * 6) Close the valve completely
 * 7) Turn on vacuum for at least 3 minutes
 * 8) Turn RF power to high. Open the vent valve on the door slowly until the plasma turns pink
 * 9) Hit the sample with pink plasma for 1 min
 * 10) Turn off RF power, vacuum, and main power
 * 11) Place glass on bench with bonding surface up. Then place the PDMS on top of the glass. Watch it bond.
 * 12) After bonding, apply a bit of force to remove any air that may remain between the PDMS and glass