Fiber optic sensor enhanced by NIR spectroscopy for bacteria identification

Recent advances in optics, lasers and optical fiber technology have caused massive increase in the interest in fiber optic sensors. At the present time, the main areas of fiber optic sensors (FOS) research are biomedicine and chemical research, environmental monitoring and industrial control. Substantial amount of benefits make FOS highly attractive for biosensing and microbiology. In microbiology, development of reliable technique for rapid bacteria identification without tedious sample preparation is still challenging. Fusion of FOS technology and NIR spectroscopy leads to development of unique device with enormous sensitivity and selectivity, which could be a perfect tool for distinguishing between bacterial species.
In the work, possibilities and limits of NIR and IR spectroscopy for bacterial identification are studied. The spectra of three common food pathogens (Escherichia Coli, Listeria, and Salmonella) were acquired. Chemical composition of bacteria were examined by transmission, diffuse reflectance and microspectroscopy techniques. Acquired data were processed by standard chemometrics methods (PCA,PLS-DA,SIMCA…), cluster analysis and artificial intelligence techniques (ANN, EA). The correct classification rate is close to 100% on limited dataset. Mass spectroscopy served as supportive technique for spectra interpretation. On the basis of gained results, a novel NIR-FOS was proposed.
Even if the initial experiments show suitability of NIR for bacteria identification, classical NIR spectroscopy does not seem to be sufficiently sensitive measurement technique for these purposes. The proposed NIR-FOS, with cavity-enhanced sensitivity, can overcome these limitations and make breakthrough in microbiology, immunology and other related areas, where the liquid sample analyze is required.