H: Patterned Silk Films – Generating a Mold TIMING: 6 hours
If reusing a mold, skip to step xii.
Prepare work area by laying down a sheet of aluminum foil and collecting the required materials (a plastic pipet, a box of Kim wipes®, a paper cup, a needle, Sylgard base and curing agent, bottle of 70 v/v% ethanol, and diffraction grating).
Critical: Ensure that the diffraction grating is free of debris. Spray with ethanol, wipe, and blow dry with pressurized air from bench top.
Place paper cup on balance, weigh out appropriate amount of base and then curing agent from the Sylgard kit. For 1 mold (5 cm × 5 cm) use 4.5 g base and 0.5 g of curing agent (10:1 ratio).
Mix with plastic pipet for 1 min.
Place PDMS in vacuum oven for 30 to 60 min to remove air bubbles.
Place the diffraction grating in a Petri dish.
Slowly pour the PDMS over the diffraction grating, try not to introduce bubbles.
Once the grating is covered, remove any bubbles with a needle.
Gently move the Petri dish to a 60°C oven for 4 hours or leave at room temperature for over 24 hrs.
Remove the PDMS from the diffraction grating. Be careful not to rip the PDMS.
Clean mold with a Kim wipe® and ethanol.
PAUSE POINT: PDMS molds can be stored at room temperature and used indefinitely. Discontinue use when there is damage present on the casting face.