Cellphone Principles Help Microfluidic Chip Digitize Information on Living Cells

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The underlying principle for the cell identification is called code division multiple access (CDMA), and it's essential for helping cellular networks separate the signals from each user. The microfluidic channels are fabricated from a plastic material using soft lithographic techniques. The electrical pattern is fabricated separately on a glass substrate, then aligned with the plastic chip

"We have created an electronic sensor without any active components," Sarioglu said. "It's just a layer of metal, cleverly patterned. The cells and the metallic layer work together to generate digital signals in the same way that cellular telephone networks keep track of each caller's identity. We are creating the equivalent of a cellphone network on a microfluidic chip."

The next step in the research will be to combine the electronic sensor with a microfluidic chip able to actively sort cells. Beyond cancer cells, bacteria and viruses, such a system could also sort and analyze inorganic particles.

The computing requirements of the system would be minimal, requiring no more than the processor power of smartphones that already handle decoding of CDMA signals. The proof-of-principle device contains just four channels, but Sarioglu believes the design could easily be scaled up to include many more channels.

"This is like putting a USB port on a microfluidic chip," he explained. "Our technique could turn all of the microfluidic manipulations that are happening on the chip into quantitative data related to diagnostic measurements.

Ultimately, the researchers hope to create inexpensive chips that could be used for sophisticated diagnostic testing in physician offices or remote locations. Chips might be contained on cartridges that would automate the testing process.

"It will be very exciting to scale this up, and I think that will open up the possibility for many different assays to become accessible electronically," Sarioglu said. "Decentralizing health care is an important trend, and our technology might one day allow many kinds of diagnostic tests to be done beyond hospitals and large medical facilities."

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