A highly sensitive optical fiber based near-infrared laser induced fluorescence detector (LIF) for parathyroid gland detection

A highly sensitive optical fiber based laser-induced fluorescence (LIF) detector was developed for identification of in-vitro parathyroid gland (PG). An optical fiber probe with included angle of 20° was designed to reduce the “blind area” and collection of reflected light. Compared with collinear bundles probe, the sensitivity was increased by 53.4% (converted to equivalent collection area), and the short-term fluctuation and long-term drift were reduced by 61.1% and 58.3%, respectively. Besides, by adding the designed dichroic mirror module to the emission optical path, the baseline and noise were further reduced by 96.7% and 92.1%, respectively, and the signal-to-noise ratio (SNR) was improved by about 9 times. The limit of detection (LOD) for CF790 dye was 5.1 × 10−14 mol/L (SNR=3, peak-to-peak noise) under evaluation of standard cuvette, which was hundreds times lower than other optical fiber based LIFs. Then, the detector was applied to detect in-vitro diseased PG samples, with diagnostic accuracy of 83.3%, which met the demand of clinical PG detection.