DETERMINATION OF CONCENTRATIONS OF BIOLOGICAL SUBSTANCES USING RAMAN SPECTROSCOPY AND ARTIFICIAL NEURAL NETWORK DISCRIMINATOR

摘要

The concentration of a substance, such as glucose, in a biological sample, such as human tissue (e.g. the skin of an index finger) (102) is non-invasive determined by directing the output beam (28) of a laser diode (21) onto and into the skin so as to cause Raman scattering. The output of a charge coupled device (40), upon which the scattered light is spatially dispersed according to frequency is digitized and applied to a processor (63). The processor compares the Raman scattering intensity characteristics of the sample with a comparative model, in particular, an artificial neural network discriminator (ANND). The ANND is trained with a plurality of Raman spectral characteristics from biological fluids or tissue, possessing known Raman scattered light intensities versus wavelength characteristics at known concentrations. A preferred implementation of the ANND employs fuzzy adaptive resonance theory mapping (ARTMAP), which has robust noise rejection capabilities and can readily handle nonlinear phenomena.