Caltech researchers have developed a "microscope on a chip" using an inexpensive lensless magnifying system that relies on a light-sensing chip to achieve the resolving power of a conventional microscope costing thousands of times more.
The chip could be incorporated in an iPod-size device that could be used by rural physicians to detect malaria parasites in blood, hikers to identify microbes in stream water, and oncologists to detect cancer cells in the blood of chemotherapy patients.
Such devices could be readily made using current technology and should be available in about five years. They would probably cost about $100, said designer Changhuei Yang, a Caltech bioengineer.
The key to the device is a thin layer of metal with a few hundred tiny holes, one above each pixel in the light-sensing chip, Yang reported Thursday in the journal Nature. A microfluidic channel, through which the sample liquid flows at a diagonal to the pixel array, is added above the metal film.
As the fluid flows through the channel, any specimens suspended in it block the passage of light to the sensors. This produces a series of images, consisting of light and shadow, akin to the output of a pinhole camera.
Because the images are skewed by the diagonal flow and overlap, they can be pieced together to create a surprisingly precise two-dimensional, black-and-white picture of the subject.
Using a processor with computing power similar to that found in a Blackberry, the device can scan cells as small as 0.8 to 0.9 microns. (A micron is a thousandth of a millimeter.) The image would be displayed on a screen and, if desired, captured to memory.
The device would be extremely rugged because "there's no lens to break," Yang said. A physician or hiker could simply "stick this in his back pocket."