Multiphysics Modeling of Laser-Bioink Interaction in Laser-Induced Forward Transfer (LIFT) for Skin Tissue Bioprinting: A Comparative Study of Pulse Duration Effects

Laser-Induced Forward Transfer (LIFT) has emerged as a promising technique for high-precision bioprinting of skin tissue constructs. However, the complex multiphysics governing the interaction between laser pulses and bioinks remains incompletely understood, particularly regarding the influence of laser pulse duration on printing outcomes and its impact on cell viability. This study presents a comprehensive axisymmetric multiphysics model comparing femtosecond (fs), picosecond (ps), and nanosecond (ns) laser regimes in LIFT bioprinting, integrating a novel theoretical framework for predicting cell viability based on thermal dose, specifically utilizing the Arrhenius and CEM43 models. Our model integrates laser energy absorption, thermal diffusion, phase change dynamics, bubble formation, and jet ejection physics to predict printing outcomes for skin tissue applications. Results demonstrate fundamentally different energy coupling mechanisms across these ultrashort (fs, ps) and longer (ns) pulses. Three-dimensional temperature profiles reveal that fs pulses generate the steepest thermal gradients ([Formula: see text] [Formula: see text]K/[Formula: see text]m) and most localized heating, followed by ps pulses, leading to more controlled bubble dynamics and jet formation compared to ns pulses. Furthermore, our theoretical predictions for cell viability indicate that ultrashort pulses (fs and ps) offer superior cell survival rates and spatial control over thermal damage compared to nanosecond pulses. This work provides a theoretical framework for optimizing laser parameters in skin tissue bioprinting applications and offers insights into the underlying physical mechanisms governing the LIFT process outcomes, with a particular emphasis on enhancing cell viability.