New microscope the size of an iPod

The old optical microscopes that everyone used in high-school biology class may be a step closer to the glass heap, as researchers at the California Institute of Technology, Pasadena, have announced the invention of an optofluidic microscope that uses no lens elements and could revolutionize the diagnosis of certain diseases such as malaria. Although similar in resolution and magnifying power to a conventional top-quality optical microscope, the optofluidic chip is only the size of a quarter, and the entire device--imaging screen and all--will be about the size of an iPod.

"This is a new way of doing microscopy," declares Changhuei Yang, assistant professor of electrical engineering. "Its imaging principle is similar to the way we see floaters in our eyes. If you can see it in a conventional microscope and it can flow in a microfluidic channel, we can image it with this tiny chip."

That list of target objects includes many pathogens that are most dangerous to human life and health, including the organism that causes malaria. The typical method of diagnosing malaria is to draw a blood sample and send it to a lab where the sample can be inspected for malaria parasites. A high-powered optical microscope with lens elements is far too big and cumbersome for inspection of samples in the field. With a palm-sized optofluidic microscope, however, a doctor would be able to draw a drop of blood from the patient and analyze it immediately. This process would be much simpler and faster than the current method, and the equipment would be far cheaper and more readily available to physicians in Third World countries.

The device works by literally flowing a target sample across a tiny fluid pathway. Normally, the image would be low in resolution because the target would interrupt the light on a single pixel, thus limiting the resolution to pixel size. However, the researchers have avoided this by attaching an opaque metal film to a microfluidic chip. The film contains an etched array of submicron apertures that are spaced in such a way that adjacent line scans overlap and all parts of the target are imaged.

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