Researchers have successfully demonstrated a spectrometer that is orders of magnitude smaller than current technologies and can accurately measure wavelengths of light from ultraviolet to the near-infrared. The technology makes it possible to create hand-held spectroscopy devices and holds promise for the development of devices that incorporate an array of the new sensors to serve as next-generation imaging spectrometers.
“We’ve created a spectrometer that operates quickly, at low voltage, and that is sensitive to a wide spectrum of light,” said Brendan O’Connor, corresponding author of a paper on the work and a professor of mechanical and aerospace engineering at North Carolina State University. “Our demonstration prototype is only a few square millimeters in size — it could fit on your phone. You could make it as small as a pixel, if you wanted to.”
The technology makes use of a tiny photodetector capable of sensing wavelengths of light after the light interacts with a target material. By applying different voltages to the photodetector, you can manipulate which wavelengths of light the photodetector is most sensitive to.
“If you rapidly apply a range of voltages to the photodetector, and measure all of the wavelengths of light being captured at each voltage, you have enough data that a simple computational program can recreate an accurate signature of the light that is passing through or reflecting off of the target material,” O’Connor said. “The range of voltages is less than one volt, and the entire process can take place in less than a millisecond.”
In proof-of-concept testing, the researchers found their pixel-sized spectrometer was as accurate as a conventional spectrometer and had sensitivity comparable to commercial photodetection devices.