Anal. Chem. MOBILE MEDICINE An attachment clips onto a cell phone to turn it into a medical device.

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Adding one more function to a growing list of applications for cell phones, researchers have developed a medical device that turns a cell phone into a miniature flow cytometer (Anal. Chem., DOI: 10.1021/ac201587a).

Doctors use flow cytometry to test for diseases including AIDS, cancer, and simple microbial infections. These conditions cause a change in a person's number of white blood cells; a flow cytometer allows doctors to quickly count the cells in a blood sample. Unfortunately, many doctors don't have access to the instruments, because a standard flow cytometer costs between $50,000 and $100,000 and is too bulky to carry to remote areas.

But, says Aydogan Ozcan of the University of California, Los Angeles, "there are 5 billion cell phones in the world." Since they also send and receive data rapidly, they are an attractive platform for developing medical equipment that can go anywhere, he says.

Ozcan and his team built a cell phone attachment from small components, including lenses for magnification, two light-emitting devices as light sources, and a plastic color filter to cut down on ambient light.

To test the device, the researchers added a fluorescent molecule that labels white blood cells to whole blood samples. Then they pumped the blood through a tiny chamber that passes over the cell phone's camera. They exported the resulting movie from the cell phone to a laptop computer that counted the fluorescent cells. The counts were accurate enough to distinguish between healthy and sick patients, Ozcan says. He hopes the attachment will be on the market in a couple of years, selling for less than $50.