레이저 및 광수력 공정을 이용한 생체재료 미세가공기술에 관한 연구

Abstract

Processing of several biomaterials, particularly enamel, MACOR and gelatin is studied. Enamel is hard biological material and MACOR is mimetic material of enamel. Gelatin is denaturant of collagen, a main component of soft tissues. Both biomaterials are used in experiments as model substances for biological tissue and these materials are used in a tissue engineering and clinical applications. In this work, we compare and analysis the machining characteristics induced by micro DOP (micro Droplet Opto-hydrodynamic Processing) and those of pulsed laser ablation. Micro DOP technique is hybrid machining processing. Laser-induced breakdown (LIB) of micro water droplet generates a high-speed pulsed micro jet, which, together with the transmitted laser pulse, can effectively and precisely ablate materials with little thermal effect. Pulsed laser ablation is conducted with two laser sources, nanosecond excimer laser and femtosecond Ti-Sapphire laser system. Morphological characteristics on irradiated area and ablation rates are investigated by optical microscope, scanning electron microscopy (SEM) and interferometric surface profiler. Processing of hard biomaterials, DOP enables micro scale removal of hard dental tissue and ceramic with similar mechanical properties, without causing thermal side effects. Furthermore, the removal rate using this process is substantially higher than that using conventional pulsed laser ablation processing. Processing of gelatin, pulsed laser ablation can control the surface topography (swelling of the surface and ablation depth) by adjusting the process parameters. In particular, femtosecond laser can ablate the gelatin without substantial thermal damages and debris.