Light spectrometry is used extensively in clinical medicine, biomedical research, and many others fields of inquiry. The machines that are able to accurately detect the wavelengths of light emitted by small objects tend to be quite large and immobile, confined to labs with samples being brought to the machines rather than the other way around. Now a pair of MIT researchers has developed an entirely new approach, which utilizes quantum dots, to reduce the size of spectrometers by orders of magnitude.
Traditional spectrometers separate light into component wavelengths using prisms and diffraction gratings, but the new approach relies on quantum dots, semiconductor nanocrystals that have quantum properties. These can be made to absorb different wavelengths of light depending on how the dots were manufactured, a property long known but never fully taken advantage of.
The new device, about the size of a large coin, includes groups of quantum dots that filter light within specific ranges of wavelengths. A camera placed behind a sheet printed with different groups of microdots can measure the amount of light that penetrates onto the photodetector. By combining the measurements gathered of light coming through different groups of quantum dots, the device is able to identify the wavelength and intensity parameters of light emitted by the object studied. While the latest prototype is able to measure light of wavelengths within about 300 nanometers, by using more groups of quantum dots that range can be significantly expanded and the resolution increased.
Study in Nature: A colloidal quantum dot spectrometer…
Source: MIT…