The influence of glucose concentration upon the transport of light in tissue-simulating phantoms

The effect of glucose upon the transport of light in tissue-simulating phantoms is shown and its possible application for non-invasive glucose monitoring in diabetic patients is discussed. The aim of this paper is to investigate the physical background of this effect. The presence of glucose in an aqueous solution increases its refractive index and therefore has an influence upon the scattering properties of particles suspended in solution. Experimental data on the effect of glucose upon the scattering coefficient and the phase function of aqueous suspensions of spherical polystyrene particles are presented for near-infrared wavelengths and compared to values predicted by Mie theory. The subsequent effect upon light transport in multiple scattering, tissue-simulating phantoms is demonstrated experimentally in a slab geometry and theoretically by applying diffusion theory. It is furthermore shown that optional measurements in the frequency domain allow changes of absorption and scattering coefficient to be separately determined. The possible magnitude of this glucose effect in tissue in vivo is discussed.