Precision Removal of Uneven Skin Tissue at Micrometre Levels by means of Focus-corrected Femtosecond-laser Ablation

Skin surgery requires micrometre levels precise tools that do not damage the healthy tissues to minimize aesthetic deterioration. Femtosecond (fs) laser has potential to realize micrometre levelsoperation in skin surgery, but the uneven skin surface which lead to laser defocus impedes the investigation of the dose-response relationship of fs-laser on skin and gives rise to secondary damage. In this study, a focus-corrected method based on two-dimensional interpolation for uneven skin surface was applied to our self-developed fs-laser microfabrication platform. Different laser powers and velocities were used for linear, planar, and 3D scanning of pig skin, respectively. The tissue elimination depths were detected via histopathology. The results showed that a micrometre levels controllable removal of target skin tissues couldbe achieved using the novel focus-corrected fs-laser ablation. The tissue elimination depth was related to the single pulse energy of the fs-laser and, within a certain range, reducing the scanning speed of the laser would not lead to a deeper tissue loss. Additionally, the use of fs-lasers for parallel linear scanning could achieve ablations of different 3D shapes. We demonstrated the focus-corrected fs-laser microfabrication platform we developed enables a micrometre levels precise removal of necrotic tissues while acceptably preserving the surrounding healthy skin by selecting appropriate fs-laser processing parameters.