Measuring temperature-induced effective attenuation coefficient spectra of biological tissue based on diffuse reflection spectroscopy

In the non-invasive blood glucose measurement based on near-infrared spectroscopy, the glucose signal is very weak and easy to be disturbed. Tissue temperature fluctuation is a primary disturbance source, since it would greatly affect the accuracy of blood glucose concentration results. We present a method called differential diffuse reflection spectroscopy, which makes a differential processing on the data from multiple source-detector distances (SDDs), and it can directly estimate the change in effective attenuation coefficient (EAC) of tissue. Using EAC spectra, we investigated the influence of temperature on the tissue spectra and then used a multivariable analysis of external parameters orthogonalization (EPO) to calibrate the spectra. The spectra of 1000-1800 nm caused by temperature and glucose are compared. Theoretical computing, Monte Carlo simulations and experiments were used to test this method. In conclusion, this proposed method using EAC spectrum to monitor the tissue change shows a promising application potential in non-invasive blood glucose measurement.