Based on NDIR gas sensor technology, the OptoScannar™ relies upon wavelengths in the visible spectrum. This technology has been recently employed for sensing glucose in interstitial fluid for improved diabetes management.
With non-dispersive infrared spectroscopy, an infrared beam passes through a sampling chamber and each gas component in the sample absorbs some particular frequency. By measuring the amount of absorbed infrared at the necessary frequency, the concentration of the gas component can be determined. It is called non-dispersive because the wavelength which passes through the sampling chamber is not pre-filtered, and instead the optical filter is in front of the detector to eliminate all light except the wavelength which the selected gas molecules can absorb.
Until recently, this sensing technique has been used sporadically for detecting concentration of molecules in the liquid phase and without much success. In the gaseous phase, molecules are very well separated in space detecting them optically is relatively free from deleterious scattering related noises.
When this optical sensing technique is used with liquids such as blood or interstitial space in the human body, the molecular density is many fold greater. This density drives noise from the greater scattering of the source radiation away from the detector. Heretofore, near IR detection of compounds in skin has been unsuccessful.
OptoScannar’s parent company, Airware, has recently introduced a new measurement technique to can control this deleterious scattering noise.