High resolution fluorescence-based temperature sensor for stand-off detection in physiological range

Fluorescence ratiometric temperature sensing system for stand-off temperature measurements in the physiological range is presented. It is based on the use of fluorescence dyes and an integrating photodetector system. The system is intended for use in neonatal intensive care units (NICU). It utilizes a measurement and a reference fluorescence dyes encapsulated in a film. Fluorescence is excited using LEDs and the emission is detected using photodiodes equipped with optical band pass filters. The current generated by the photodiodes is integrated and the charge is digitized. The fluorescence intensity is calculated as the difference in the measured intensities when the LED is on or off. The ratio of the two emission intensities depends linearly on the temperature. The system operates under room-light illumination with resolution <;0.1°C at a rate 1 sample per second. It is capable to better suppress the influence of the ambient light intensity as compared with previous camera based systems.