Study on precise identification of remote bacterial species using multi-temporal LIBS optimized by plasma electron temperature coefficient of variation

Abstract

Background

Laser-Induced Breakdown Spectroscopy (LIBS) has demonstrated significant potential in microbial detection due to its rapid, non-contact, and multi-element analytical capabilities. However, remote detection is hindered by challenges such as signal attenuation and the high similarity of spectral features, which reduce classification accuracy. To address these issues, this study proposes a multi-temporal LIBS remote identification method optimized based on the plasma electron temperature coefficient of variation (CV_T). By analyzing CV_T values across different delay ranges, optimal time delays were selected and combined to amplify spectral differentiation, thereby improving classification performance.

Results

A coaxial-design LIBS telemetry system with adjustable focus was constructed, and multi-substrate telemetry testing was conducted on 10 common pathogenic bacteria at distances of 5 m and 10 m. By optimizing multiple temporal delays within the 100–1000 ns range, the classification performance of single-temporal, dual-temporal, and multi-temporal spectral combinations was evaluated. The results showed that the multi-temporal approach improved the classification performance across all substrates. At a distance of 5 m, a 100 % identification rate was achieved for all substrates, with Precision, Recall, and F1-score all reaching 1.0. At 10 m, the identification rate for the aluminum substrate increased from 76 % to 93 %. In addition, the contribution of the four major elements, Ca, Na, C, and K, was found to account for up to 60 % of the classification results.

Significance and novelty

It is demonstrated that the CV_T-optimized multi-temporal LIBS technology effectively overcomes the signal attenuation bottleneck at long distances, significantly enhancing the robustness and analytical capability of remote microbial identification. This approach provides a novel method for remote detection in areas such as public safety, medical diagnostics, and military defense.