Gas in scattering media absorption spectroscopy – from basic studies to biomedical applications

Abstract The recently introduced Gas in Scattering Media Absorption Spectroscopy (GASMAS) technique provides novel possibilities for analysis in biophotonics. Free gas in pores or cavities is monitored with narrow‐band laser radiation, which can discern the gas absorptive imprints which are typically several orders of magnitude more narrow than the features of the surrounding tissue through which the diffusely scattered light emerges to the detector. Important gases monitored are oxygen and water vapour. Applications include diagnosis of human sinus cavities and surveillance of neonatal children, but also characterization of food‐stuffs, food packages and pharmaceutical preparations. Non‐biological applications include the study of construction materials such as wood, polystyrene foams and ceramics. For nano‐porous materials, information on the pore sizes can be obtained from observed line broadening. Apart from concentration measurements, the GASMAS technique also allows the study of gas transport and diffusion, and pressure and temperature information can also be obtained.