Skin temperature measurement based on diffuse reflection light at scattering variation independent source-detector separation

Abstract

This study presents a method for predicting skin temperature using near-infrared light at 1314 nm and 1409 nm wavelengths. Skin temperature is a critical factor in the precision of in vivo optical measurements, necessitating accurate determination. Our approach detects temperature-induced tissue absorption changes, utilizing absorbance variations at specific scattering independent source-detector separations (SVI-SDSs) to estimate temperature. The 1409 nm wavelength is the main indicator for temperature prediction, with the 1314 nm wavelength used to identify the SVI-SDS for the 1409 nm light. Experimental data from four subjects were collected using an optical sensor across five SDSs ranging from 0.9 mm to 2.3 mm. We identified the SVI-SDS for the 1409 nm light at approximately 2.3 mm, where absorbance exhibited the most sensitivity to temperature changes, resulting in the lowest root mean square error (RMSE) and highest temperature sensitivity. These findings offer a valuable reference for the real-time monitoring and calibration of in vivo skin temperature, enhancing the accuracy of optical measurement techniques.