A comparative study of nanosecond laser wavelengths for improved LIBS analysis of soft tissues

Abstract

Laser-based techniques, such as LIBS, enable rapid elemental detection and spatially resolved mapping of biological tissues; however, their performance strongly depends on the laser–matter interaction and the physical and chemical properties of the sample. Since every material responds differently to laser radiation, each matrix generates plasma with distinct characteristics, and the emissions of individual elements evolve uniquely during the plasma lifetime. Soft tissues, due to their natural complexity and heterogeneity, therefore, require careful optimization of measurement parameters. In this work, we systematically investigated the influence of nanosecond Nd:YAG laser wavelengths (266 nm, 532 nm, and 1064 nm), pulse energy, and gate delay for collection on LIBS analysis of mouse liver tissue in ambient air and under argon purging. For each wavelength, a defined range of pulse energies and gate delays were explored. LIBS performance was evaluated using irradiance calculations, signal-to-noise ratios, and the relative standard deviation of selected biogenic elements (Mg and Ca). Moreover, the ablation crater diameter and depth were analyzed to assess the effect of irradiation on tissues and to determine the spatial-resolution limits for LIBS elemental mapping. The results demonstrate that optimized parameter combinations significantly improved the signal quality and crater characteristics, highlighting the potential of LIBS for reliable elemental analysis of biological tissues.