Researchers at Princeton University have made a huge step towards enabling laboratory-quality diagnostics with handheld devices. They adapted silicon chip technology similar to that found in personal computers and mobile phones to function as a biosensor, which uses tiny metal layers embedded in a microchip to eliminate all complex, bulky, and expensive optical instrumentation employed in the diagnostic labs. The chips take advantage of light's unusual behavior when interacting with structures smaller than a single wavelength of light. Harnessing the light in this way allows for detection of thousands of biological substances from bacterial DNA to hormones. Although the researchers said more work is necessary, they expect the technology to lead to diagnostic systems contained in a pill or deployed on a smartphone.