The Shrinky Dink Solution

From Technology Review:

In 2006, Michelle Khine arrived at the University of California­'s brand-new Merced campus eager to establish her first lab. She was experimenting with tiny liquid-filled channels in hopes of devising chip-based diagnostic tests, a discipline called microfluidics. The trouble was, the specialized equipment that she previously used to make microfluidic chips cost more than $100,000--money that wasn't immediately available. "I'm a very impatient person," says Khine, now an assistant professor at the University of California, Irvine. "I wanted to figure out how I could set things up really quickly." Racking her brain for a quick-and-dirty way to make microfluidic devices, Khine remembered her favorite childhood toy: Shrinky Dinks, large sheets of thin plastic that can be colored with paint or ink and then shrunk in a hot oven. "I thought if I could print out the [designs] at a certain resolution and then make them shrink, I could make channels the right size for micro­fluidics," she says. To test her idea, she whipped up a channel design in AutoCAD, printed it out on Shrinky Dink material using a laser printer, and stuck the result in a toaster oven. As the plastic shrank, the ink particles on its surface clumped together, forming tiny ridges. That was exactly the effect Khine wanted. When she poured a flexible polymer known as PDMS onto the surface of the cooled Shrinky Dink, the ink ridges created tiny channels in the surface of the polymer as it hardened. She pulled the PDMS away from the Shrinky Dink mold, and voilà: a finished microfluidic device that cost less than a fast-food meal.

Read the whole article