One-dimensional thermomechanical bio-heating analysis of viscoelastic tissue to laser radiation shapes

Abstract

This article studies the coupled thermo-vibrational response of skin tissues to different laser irradiation inputs. The presented model uses four different phase lags to capture various mechanical responses, like viscoelastic properties of the skin, the finite thermal propagation speed, thermal inertia, or temperature gradient phase lag. Here the dynamic motion differential equation of the skin tissues is jerk dependent and expressed through a third-order time derivative due to the stress dependence of the constitutive behavior. The transient response of the model for various laser inputs is obtained through numerical integration over time. Experimental studies with various applicable laser input samples are tested in the laboratory. The obtained temperature results of these studies are compared with the numerical results to validate the model. In this comparison, good agreement was obtained despite the one-dimensionality of the modeling due to the large radiating area. Furthermore, the steady-state response due to a harmonic laser irradiation input is obtained to evaluate the temperature and displacement in the tissue and validate the simulation results. The results illustrate that tissue response depends on the steady amount of different energies in different periods. By controlling the energy and the radiation of the tissue, the expected tissue response can be received with the least entered energy.