Low cost laser induced breakdown spectroscopy technique for detection of microorganisms

Identification of microorganisms using Laser Induced Breakdown Spectroscopy (LIBS) is currently an experimental technique in the early development stage. The highly expensive and complex instrumentation involved in this technique is a severe limitation to its translation into a commercial diagnostic device. In this study, we have investigated the efficacy of using low cost, non-intensified and portable CCD spectrometer systems for identification and discrimination of microorganisms, such as species of gram-positive (Staphylococcus aureus) and gram-negative bacteria (Escherichia coli and Klebsiella pneumoniae) using their spectral fingerprint. Comparison of the resulting emission spectra from these detectors, on ablation using nanosecond pulsed Nd: YAG (1064 nm) laser source has been carried out. We have established the efficiency of classification for discrimination between gram-positive and gram-negative bacteria and also between 2 different species of gram negative bacteria. We also present the results of ablation of the microbial smears on several organic as well as inorganic substrates and their relative efficiency in identification of the microbial species. The results indicate the feasibility of porting this technique onto a PDMS (Polydimethylsiloxane) or paper based microfluidic point of care device which can eliminate the complex sample preparation steps required currently. This study has huge potential for the development of a low-cost commercial LIBS based microfluidic device for detection of microorganisms.