Modelling of Direct Laser Patterning of Self Assembled Monolayers (SAMs) on Cobalt-Chromium Alloy

Abstract

The implantation of biomedical devices is often accompanied with complications such as post-operative infections, lack of tissue integration, and biofilm formation. A strategy that will limit these complications by administering a focused multi-therapeutic treatment is needed. The direct laser patterning of self-assembled monolayers (SAMs) onto the implant can be used to modify the surface and provide a platform for multi-therapeutic treatment. Conventionally, surface patterning of SAMs requires a uniform surface, but most bio-implants are irregularly shaped. Laser patterning is able to bypass this problem and modify the surface of an implant of irregular shape with precision. Effective optimization of patterning process is needed to minimize experimental trials and error for the development of laser assisted patterns. In this abstract, we report the development of a model to simulate the direct laser patterning process on Cobalt-Chromium (Co-Cr) Alloy. COMSOL Multiphysics 4.3b was used to create the 3D model. Governing equations associated with heat transfer in solids were used with the heat source being the heat provided by the laser. The model calculated the resulting temperature gradient on the cobalt chromium surface giving an indication of SAM desorption based on the surface temperature of the metal. Temperature profiles as simulated by the model indicated a laser etch diameter of approximately 11µm. Experimental results of direct laser etching of SAMs on cobalt chromium alloy gave a laser etch of 12µm. The close proximity of the predicted and experimental diameter confirms the validation of the developed model.