Originally Published MPMN October 2009

Biomedical engineering isn't exactly child's play--unless you're Michelle Khine. The 32-year-old engineer drew inspiration from a popular low-tech children's toy to fabricate a sophisticated yet inexpensive microfluidic device that demonstrates the power of creative thinking.

The field of microfluidics has attracted widespread interest in the medical device sector. Following the ubiquitous biomedical trend of miniaturization, microfluidic systems have tremendous potential in next-generation clinical diagnostic and lab-on-a-chip devices. Unfortunately, the diminutive devices can also come with significant overhead.
Primarily employing precision etching or lithography techniques on silicon substrates, microfluidic chip fabrication can require equipment sporting a six-figure price tag. Khine discovered this harsh reality when embarking on microfluidics research in her first lab at the University of California's Merced campus several years ago. And she realized that she had to get creative if she wanted to pursue her research.
Taking a stroll down memory lane led Khine to a toy she enjoyed in her youth: Shrinky Dinks. Consisting of plastic sheets fashioned into shapes, Shrinky Dinks are designed to be decorated and then placed into an oven for two minutes. During that time, the plastic shrinks to roughly 1/3 its original size and becomes nine times thicker.
A seemingly magical miracle to children, the toy could serve, Khine thought, as a simple platform for microfluidic systems. "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," Khine told MIT's Technology Review, which named her a 2009 Young Innovator.
Her hypothesis was correct. The Shrinky Dinks proved to be a sufficient material on which Khine could print an AutoCAD-generated channel design. When heated in an oven, the ink clumped and formed ridges. Upon cooling of the plastic, Khine poured the polymer PDMS on the surface of the toy. As it hardened, the ink ridges created minute channels in the surface of the flexible polymer. Removing the PMDS from the Shrinky Dink mold yielded the final product. Since her initial prototypes, Khine has moved on to etching the channel design directly in the Shrinky Dink using syringe tips, a technique that produces the narrow but deep channels desired for microfluidics.
Although Khine admits there are some flaws in her method, it is a truly unique and functional approach to microfluidic system design. Using a children's toy that is sold in packs at the store for typically less than $20, Khine is able to produce--in mere minutes--a unique and functional microfluidic system. This kind of innovative thinking and determination is what spurs true progress. Researchers, designers, and engineers should follow Khine's example and problem solve using knowledge gleaned outside of the lab as well. After all, inspiration can come from anywhere, and, as cliché as it sounds, it's important to think outside the box. Unless, like Khine, you find inspiration inside the toy box.
Shana Leonard
Editor
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