A sensitive portable fluorometer coupled with miniaturized integrating sphere

摘要

This paper presents a portable fluorescence detector with a tested limit of detection (LOD) at 0.4?nM of the fluorescein solution. This detector was prototyped with a miniaturized integrating sphere that couples a sample-filled glass flow-cell, a 450?nm laser diode, a 550?nm long-pass optical filter, and a light sensor. The integrating sphere is shown to improve the sensitivity and resolution of detection by collecting all the fluorescence emanation. A comparative study with two integrating spheres of 0.75-in. diameter, reflective versus black, shows that the former enables (1) a larger amount of irradiance at the light sensor, (2) a lower LOD, and (3) better resolution of detection. An estimation of the battery lifetime is given for various scenarios of operating this fluorometer for measurements.