Procedure developed by
Joseph Muskin and and Mechelle Noronha from the Center for Nanoscale Chemical-Electrical-Mechanical
Manufacturing Systems, University of Illinois, Urbana-Champaign.
A fluidic channel is created in polydimethylsiloxane
by casting the PDMS on a master made with puffy paint. PDMS is cured by an
organometallic crosslinking reaction to
give an optically transparent polymer. Different colored isopropanol is dispensed
into the channels to observe fluid mixing.
Trace a petri dish. Mark the location of the holes in the plexiglas square.
Draw a Y-shape connecting the holes.
Place a petri dish over the paper with the pattern. Dispense puffy
paint along the pattern.
Measuring the viscous PDMS liquid can be messy. Cover the work surface
and the balance with aluminum foil. Wear gloves.
Add xxxx g of Sylgard polymer
base to a plastic cup. Add xxxx
g of curing agent using a disposable dropper. Thorough mixing of the PDMS
components is essential for good curing.
After the puffy paint has hardened, add the PDMS mixture.
Evacuate to remove bubbles from the PDMS. (It will look like even
more bubbles appear in vacuum but when air is reintroduced the bubbles
will pop.) Alternatively waiting and gently blowing over the surface may also eliminate bubbles.
Cure the PDMS at 60 degrees C for an hour.
Remove the PDMS from the Petri dish.
Make a plexiglas sandwich with a PDMS filling, being sure that the
holes drilled through the plexiglas align with the ends of the channel.
Add colored isopropanol to each channel. Do the solutions mix?
Plastic Petri dish
Plexiglass rectangle with holes and not with holes