Laser-induced breakdown spectroscopy in a biological tissue

The relative atomic composition of the laser-generated ablation plume in chicken myocardium is investigated by using luminescence spectroscopy. A Q-switched Nd:YAG laser emitting at 1064 nm with 9 ns pulse duration was used for the tissue ablation. The selected ou tput energy was 210 mJ and the beam was focused to a 0.8 mm diameter spot size by using a 40 cm focal length lens. The luminescence emitted by the lasers-generated plasma due to the tissue ablation was collected by a 600 μm fused silica fiber. The collected light was coupled into a o m spectrometer. An intensified CCD with 256 x1024 pixels was connected a t t he monocromator detector port. The specified CCD gating capability was 5 n s and it was controlled b y a DG535 model delay generator. The gate width was adjusted electronically to the desired time window. Four gates (100 μs, 10 μs, 5 μs and 100 ns) were tested and the ideal one, that presented more information about the samples under s tudy, was the 5 μs window. The analysis of the spectral emission pointed out the presence of sodium, potassium, calcium, hydrogen and others. Each element was identified separately and compared to the c ommon elements in tissues. In the extra-cellular matrix the presence of sodium prevails and in the intra-cellular s pace potassium predominates together with calcium and magnesium. The water diffusion through the membranes of living tissues carries ions of these elements. The perfect equilibrium between these distributions is necessary for the healthy maintenance of the organism. The measurement of the relative atomic composition by means of the laser ablation might lead to a diagnosis technique for the discrimination of different materials or tissues and even pathological conditions that promote chemical alterations to them.