Miniaturised spectroscopy has potential for portable greenhouse gas monitoring

Fourier-transform Infrared (FTIR) spectroscopy is a basic tool for chemistry. Infrared radiation excites the bonds between atoms in organic molecules, making them vibrate at a frequency which is characteristic to the type of bond. The main advantage of FTIR is that it uses a burst of multifrequency infrared radiation, rather than slowly scanning across frequencies. Processors incorporated into the spectrometer analyse the waveform transmitted through the sample, using a mathematical technique called a Fourier transform to derive the frequencies which were absorbed.

Despite this being a very established technology, FTIR spectrometers are large instruments, usually confined to laboratories. Researchers from the University of Campinas’ device research laboratory in Brazil, collaborating with colleagues at the University of California San Diego, have now developed an FTIR spectrometer based on silicon photonics, a technique which uses the optical properties of silicon, whose components can be made using the same processes used to mass manufacture electronic components.