by R. Colin Johnson, EE Times
PORTLAND, Ore. — Michelle Khine, a professor at the University of California at Irvine, will be honored next month for inventing a method for fabricating microfluidic devices without a clean room.
Khine will be one of 35 innovators under age 35 to be honored during the Massachusetts Institute of Technology’s Emerging Technologies Conference (EmTech2@MIT, Sept. 22-24).
She used a toy called Shrinky Dinks (K&B Innovations Inc. (North Lake, Wis.) to make prototypes of a microfluidic lab-on-a-chip. Traditional microfluidic channels used for routing fluids through a battery of tests are manufactured in a clean room using semiconductor and MEMS fabrication equipment. Khine’s innovation was to print microfluidic channels on Shrinky Dink plastic sheets, then shrink them in a low-temperature oven from the millimeter to the micron scale.
Khine founded Shrink Nanotechnologies Inc. (Carlsbad, Calif.), which is developing a prototyping method for both microfluidic devices and one-time medical tests for used as medical scaffolds to grow stem cell tissues and for a new type of solar concentrator. Khine claims the latter technology could advance the solar panel industry by shifting out-of-range wavelengths like ultraviolet into the infrared range frequencies already converted by conventional solar cells into electricity.
“It all started as just a way of making microfluidic devices–labs-on-a-chip–which had been piggybacking on
semiconductor and MEMS fabrication equipment using standard photolithorgraphy,” Khine said. The latter requires a clean room, “but that is such overkill for microfluidics where 100-micron resolution is all that’s required.”
Using their own version of the Shrinky Dink material, Khine demonstrated how an ink-jet printer can be used to emboss the microfluidic channels necessary to create labs-on-a-chip. The ink forms the microfluidic channels as raised lines with millimeter resolution. When shrunk down to micron sizes, the features become about nine times taller with rounded edges–the perfect aspect-ratio and shape for microfluidic channels.
Liquid plastic is poured in the resulting template, where the raised lines become mirror images–channels–which can be peeled off as a finished device after cooling.
Since recruiting Heiner Dreismann, former Roche Molecular Systems president and CEO, Khine’s company has
discovered several related applications for its process. For instance, by embedding small metallic components
alongside fluorescent materials used to sense medical conditions, Shrink Nanotechnologies claims to have harnessed metal-enhanced fluorescence for inexpensive medical assay tests, which it hopes to market by 2010.
The solar concentrator application is a film that can be installed like a window shade over the top of existing solar panels to shift UV frequencies into the infrared range, thereby enhancing their efficiency. The technique works by embedding frequency-shifting quantum dots into the transparent material before it is shrunk. Incident UV wavelengths, which are usually wasted in conventional solar cells, are then absorbed by the quantum dots, then re-emitted as the near infrared wavelengths which can be converted by a conventional solar cell.
“We think it could become a standard accessory for solar cells,” said Khine.
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