Processing of Biomedical Tissue Materials by Femtosecond Laser Pulse

Abstract

The micromachining of hydroxyapatite (HAp) and collagen is highly required for orthopedics and dentistry, because human bone and tooth consist mainly of HAp oriented along the collagen. We have evaluated ultrashort Ti:sapphire laser ablation of HAp and collagen with pulsewidth of 50 fs -2 ps at 820 nm and 1 kpps. The crucial medical issue is to preserve the chemical property of the ablated surface. If chemical properties of HAp and collagen change once, the human bone or tooth cannot re-grow after laser processing. Using x-ray photoelectron spectroscopy we have observed chemical properties of the HAp ablated in air. As a result it is found that the ablated surface is unchanged after laser ablation over the pulsewidth range used in this experiment. Human tooth enamel is precisely ablated with 60 fs and 2 ps laser pulses. Collagen is also found to preserve the initial infrared properties during 160 fs laser ablation.