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How to make PDMS membranes

PDMS is the acronym for polydimethylsiloxane which is a liquid silicon-based organic polymer. A cross-linking agent is added to the polymer to get a solid and rubbery compound. We can give any shape to the solid compound by pouring the polymer/cross-linker solution in a mold. The stiffness can be controlled by the concentration of the cross-linking agent in the polymer/cross-linker solution and the temperature and time of curing. Dow Corning sells a kit (liquid PDMS + liquid cross-linker) called Sylgard 184 for making solid PDMS polymer.

  1. Pour the cross-linker and the PDMS at a ratio of 1:10 by weight (cross-linker:PDMS) in a weighing dish.
  2. Mix for 5 mins with a pipette tip. A uniform mixture is essential to get uniform mechanical properties.
  3. Put the solution in a vacuum chamber to get rid of the air bubbles introduced during the mixing process.
  4. Cure the mixture at 80 degrees for at least 4 hours.

Remember, increasing cross-linker concentration (2:10 or 3:10) and/or curing time and temperature will increase stiffness.

Funtionalization procedure coming soon