Intelligent Machines

Sorting Out Life

Rubber chip promises a cheap way to segregate cells.

To understand disease and develop new drugs, researchers often must begin by sorting the jumble of cell types in a living organism-tumor cells from normal cells, for instance. In some cases, a refrigerator-sized “fluorescence-activated cell sorter,” or FACS, can do the job. These machines, however, are expensive ($250,000), tricky to operate and prone to contamination. Now a team at Caltech, led by applied physicist Stephen Quake, has built a “microFACS,” reducing the complicated system of pumps, tubes and nozzles to micrometers-wide channels in a stamp-sized rubber chip.

George Whitesides, a Harvard University chemist who developed some of the technology used by the Caltech team says, “Quake brings the perspective of a physicist to this problem in bioanalysis, with results that are, to me, spectacular.” Bay Area-based Mycometrix aims to make prototype microFACS systems available to potential customers by year’s end; the startup was formed in 1999 to commercialize technologies from Quake’s lab. Vice president of business development Todd Krueger estimates that the reader will sell for $40,000, the disposable chips for less than $20 apiece. By making cell sorting cheaper and simpler, he says, the system should open up a host of new applications for the technique outside the lab, including doctor’s-office diagnosis and food or water screening.

The microFACS uses laser light and electricity to sort a cell mixture. Three 2-millimeter-wide wells on the chip are connected by a T-shaped network of channels. A researcher first tags the cells with fluorescent markers, then loads them into the bottom well and drives them toward the channel junction with an electric current. The channels narrow to just a few micrometers near the junction, forcing the cells to proceed in single file. A laser aimed at the junction hits the different markers and causes each cell type to fluoresce in a particular color-say, red for tumor and blue for normal. A detector prompts a computer to adjust the current to drive each cell to the left or the right, into a waste well or a collection well.

This story is part of our January/February 2000 Issue
See the rest of the issue
Subscribe

One reason the microFACS is so cheap is that the chips are made by soft lithography, an experimental process developed by Whitesides. It’s potentially far less expensive than micromachining; instead of carving individual chips, researchers cast them in a reusable silicon mold.

Whitesides calls Quake’s cell sorter “an elegant piece of design,” and points out that it could be coupled to other ultrasmall analytical systems, such as single-cell DNA sequencers. Indeed, one of Quake’s future aims is to build the sorter and all the other scaled-down devices needed for a particular experiment linked together on one chip, a goal that many others in the field are hotly pursuing.

Become an MIT Technology Review Insider for in-depth analysis and unparalleled perspective.
Subscribe today

Uh oh–you've read all five of your free articles for this month.

Insider Premium

$179.95/yr US PRICE

More from Intelligent Machines

Artificial intelligence and robots are transforming how we work and live.

Want more award-winning journalism? Subscribe to Insider Premium.

  • Insider Premium {! insider.prices.premium !}*

    {! insider.display.menuOptionsLabel !}

    Our award winning magazine, unlimited access to our story archive, special discounts to MIT Technology Review Events, and exclusive content.

    See details+

    What's Included

    Bimonthly home delivery and unlimited 24/7 access to MIT Technology Review’s website.

    The Download. Our daily newsletter of what's important in technology and innovation.

    Access to the Magazine archive. Over 24,000 articles going back to 1899 at your fingertips.

    Special Discounts to select partner offerings

    Discount to MIT Technology Review events

    Ad-free web experience

    First Look. Exclusive early access to stories.

    Insider Conversations. Join in and ask questions as our editors talk to innovators from around the world.

You've read of free articles this month.