Christian Niederauer/Notebook/RacingBacterias/Protocols/Microfluidics/PDMS

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How to Create a PDMS-Stamp from Silicone/Araldite Mold

Preparation of PDMS mixture

  • with pipette boy and 5ml stripette pour ~4g of elastomer into a cup
  • with micropipette (1000µl) add one tenth of elastomer mass (~0.4g) of linker fluid to the cup
  • mix well with stripette
  • degass for 30min-60min

Preparation of PDMS membrane

  • pour degassed mixture onto wafer placed in petri dish with aluminium foil
  • pour just enough to cover the waver
  • use Leveling Petri Dish to ensure constant thickness
  • araldite wafer: cure it for 3-4 hours in oven at 60°C
  • silicon wafer: cure it for 2 hours in oven at 80°C for
  • peel off membrane from wafer surface with forceps
  • cut out the pattern but leave enough space around it

Final Processing

  • punch holes with 2mm coring tool at the desired connection points under dissection microscope (tip: target the hole with coring tool under microscope, then put the stamp onto one finger with alufoil between stamp and finger and push/turn until you feel the coring tool on your skin)
  • plasma Clean the treated face of the stamp and a coverslip and press them together with alufoil in order to prevent contamination


If the stamp is too thin

BEFORE PUNCHING HOLES

  • take a slice of PDMS with bigger or same area than the stamp
  • plasma Clean unshaped face of stamp and extra slice and stick them together
  • now punch desired holes with 2mm coring tool