The same chip found in digital cameras can produce high-resolution images of cells, thereby turning it into a microscope a without a large conventional lens. Inventor and Caltech engineer Changhuei Yang says such devices could be made for about $10 each and built into arrays for high-throughput imaging in biology labs. And by building shirt-pocket-size devices, the microscopes could let doctors in remote locations carry sophisticated imaging systems.

The device uses microfluidics or small channels to direct cells and even microscopic organisms over the light-sensing chip. A thin layer of metal covers the chip to block out most of its pixels. Light enters through a few hundred apertures punched in the metal along the fluid channel. Each aperture captures an image as a sample flows through the device. One version of the design uses gravity to control the sample flow across apertures. Another drives cell flow with an electric potential.

An overhead light source, such as sunlight, illuminates samples. Simple image-processing software then combines the 100 to 200 images. Resolution is similar to a conventional microscope, about a micrometer, and is limited by the aperture size. The processing power in a PDA is enough to run calculations, says Yang.

Such microscopes could be manufactured in conventional semiconductor fabs and grouped in arrays of hundreds for high-throughput imaging. And image-processing software could be written to automatically look for cells of interest in samples, freeing up researchers' time.

Yang sees several applications. “The standard way to detect malaria examines blood under a high-power microscope. But conventional microscopes are too fragile, cumbersome, and power hungry for use in many where the blood parasite is prevalent. Chip-based microscopes, however, could be inserted into PDA-size devices that display images on small screens and cost about $100. The devices might also be useful for tracking cancer,” he says.

Yang is also working on modifications to increase the scopes' resolution and let it handle fluorescence imaging. The design does not yet detect colors. If talks with manufacturers pan out, the microscope-on-a-chip could be available in five years.