Bubble Formation Modeling During Laser Direct Writing of Glycerol Solutions

Laser direct writing, a noncontact modified laser-induced forward transfer (LIFT) technique, has emerged as a promising technology for various applications from microelectronics printing to biofabrication. For it to be a viable technology, the bubble formation process during laser direct writing should be carefully examined. In this study, the bubble formation process during the laser direct writing of glycerol-water solutions has been studied using a nucleation-based phase explosion modeling approach. The effects of laser fluence and material properties of glycerol solution on the resulting bubble geometry have been examined both analytically and experimentally. Overall, a satisfactory modeling accuracy has been achieved, while the proposed modeling approach slightly underestimates the bubble diameter. Both the measured and predicted bubble diameters increase when the laser fluence increases. Interestingly, the measured and predicted diameters first decrease, then increase, and decrease again with the increase of glycerol concentration. Furthermore, it is noted that the bubble diameter is more sensitive to the laser fluence than the glycerol concentration.