Bubble Dynamics during Laser Irradiated Thermo-Mechanical Response of Pigmented Skin Phantom

During the laser treatment of pigmented dermatosis such as Nevus of Ota, vapor bubbles will be generated by the laser with short pulse width and high energy density. Laser irradiation is efficacious for the clinical treatment of Ota's Nevus caused by hyperplasia of melanosomes in dermis. Since the mechanism of the laser-melanosome interaction is not yet clear, the clearance rate is generally low and bleeding of irradiated skin frequently occurs. This work conducted a flow visualization experiment to investigate the laser-melanosome interaction mechanism by using high-speed imaging. Pigmented phantom was prepared to simulate the diseased dermis tissue, where agar acted as substrate and synthetic melanin particles was infused as hyperplastic melanosomes. Putting the phantom into water, its thermo-mechanical responses to single-pulse 1064-nm Nd:YAG laser irradiation with energy density of 4-7 J/cm(2) and pulse duration of 6 ns were recorded. The results indicated that laser-induced bubble formation caused by the gasification of tissue moisture is the key mechanism of laser-melanosome interaction, and an optimal energy density of 6 J/cm(2) is recommended.

Automated summary

This study investigated the laser-melanosome interaction mechanism through a flow visualization experiment using a pigmented phantom. The results suggest that laser-induced bubble formation is the key mechanism, with an optimal energy density of 6 J/cm(2) recommended for treatment.