Laser-induced Breakdown Spectroscopy (LIBS): Screening of Human lifestyle using fingernails

Laser-induced Breakdown Spectroscopy (LIBS) is a rapid, non-invasive analytical technique which makes it particularly well-suited to biomedical screening applications. For biomedical screening applications usually blood samples are used. Unlike blood samples, which exhibit short-term fluctuations and require an invasive puncture to collect, fingernails allow long-term health assessment over several months due to their slow growth. In this study, 43 fingernail samples from volunteers were analysed to determine sex, age and lifestyle factors. LIBS revealed differences in elemental composition: women exhibited higher Ca/K intensity ratios, whereas men showed higher Mg/K and H/K levels. Age significantly influenced the concentrations of the elements C, Fe, H, Mg, N, Na, O, and S. Non-drinkers displayed higher Ca/K, Fe/K and Mg/K levels. Dietary factors showed significant influence for Ca, N, Na, O and S on elemental concentrations. These findings were statistically validated using mixed models. Regardless of sex, age, or lifestyle, LIBS analysis identified three distinct spectral groups with characteristic patterns across all measurements, suggesting previously unrecognised physiological relationships. These results demonstrate the potential of LIBS for the non-invasive, long-term monitoring of elemental status and lifestyle parameters via fingernail analysis. This could create new opportunities for screening human lifestyles or clinical disease indicators.