Trace explosive detection based on fluorescence sensing and similarity measures for time series classification

Currently, almost all explosives involved in bombings are nitro compounds, especially 2,4,6-trinitrotoluene (TNT) is the most widely used. In order to detect and prevent potential explosive threats in time, it is of great significance to detect trace TNT quickly and conveniently. We investigated a fluorescence sensor and designed a trace explosive fluorescence detection system for detecting TNT acetone solutions and common chemical reagents. Experiments were conducted on the detection of TNT acetone solution with different concentrations, common chemical reagents, the influence of different injection volumes and injection flow rates, and the influence of UV irradiation time. In addition, the time series similarity measures, including the Pearson correlation coefficient, Spearman correlation coefficient, Dynamic Time Warping (DTW) distance, and Derivative Dynamic Time Warping (DDTW) distance, were used to classify the detection results. The results show that the limit of detection (LOD) of the fluorescent sensor for TNT acetone solution is 0.03 ng/μL, and the response time is less than 5 s. Moreover, the fluorescent sensor is specific, reversible and repeatable, and the recovery response time is less than 1 min. In addition, the method of integrating the calculation of Spearman correlation coefficient and DDTW distance can effectively classify the detection results.