'Labs On A Chip' May Detect Diseases In The Field

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Can the most modern of technologies help solve the health woes in the poorest countries in the world? Some biomedical engineers say yes. They are designing diagnostic laboratories that fit on something as small as a credit card, and give results in minutes instead of hours or days.

These devices are sometimes referred to as a "lab on a chip." To use them, all you need to do is obtain a drop of someone's blood.

"The drop of blood goes into the chip, and you wait about 15 minutes, and you will get the results," says Samuel Sia, a professor of biomedical engineering at Columbia University in New York. Inside the chip are tiny channels that expose the blood to chemicals that can detect diseases.

If a disease is present, a dark line will appear in a window on the chip. You can read the results by eye, or if you want to be more precise, you can use a simple reader.

"You don't need an expensive microscope or something with lasers to look at it — it's something you can build with components from RadioShack if you want," he says.

In the current issue of Nature Medicine, Sia and his colleagues describe a chip that can detect the presence of both the AIDS virus and syphilis in someone's blood. Tests in Rwanda showed they could detect these diseases nearly 99 percent of the time.

"You really want high sensitivity because if you want to have a test be used as a screening test ... you don't want to miss people who can possibly have the disease," says Sia.

Simple And Robust

Not only is the test portable, it's relatively cheap. The chip itself is only 10 to 20 cents. The cost goes up once you add in the chemicals you need and the appropriate packaging, but "we think we can do it for $2 to $3 dollars per chip, and that would include the ability to diagnose multiple diseases on one card," he says.

The device Sia has produced is not yet ready for widespread use. But Catherine Klapperich of Boston University says she's impressed with Sia's work. Klapperich is also building these labs on a chip.

"What makes Sam's approach and the approach of this group unique is that they are focused on making the instrumentation simple to use and robust to use in a low-resource environment," she says.

Klapperich says it seems straightforward to transfer this technology to countries with limited resources. "But once you start designing these things, and you really go to the developing world and you look at how people are doing clinical medicine, and you realize all of the things you can't take for granted," says Klapperich. "Even though you think it's very simple, it's not very simple.

So, even some who are enthusiastic about these devices worry they may never live up to their promise. Bernhard Weigl is a staff scientist at PATH, an international nonprofit organization that tries to bring appropriate health technologies to developing countries. Weigl says for these devices to be truly useful, they will have to be able to test for several diseases at once. And that's where the problems start.

"Pretty soon you have sort of a relatively complex system that either costs a lot, or is complex to use or has a lot of potential failures and such things," says Weigl. "So, because of those drawbacks, it's still not — after probably about seven, eight or maybe 10 years of people working on this — it's still not completely clear that this is really going to be the way to go."

Cheap, easy to use, accurate. Easy to say, hard to accomplish.



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