Process parameter optimization of pulsed laser deposition of hydroxyapatite coated polymer implant for better surface roughness and cell viability

In this work, the roughness of the implant was predicted by statistical and experimental methods. A customised bone implant was fabricated using the additive manufacturing process. Hydroxyapatite was deposited on the implant using Pulsed Laser Deposition. Taguchi philosophy was used to determine the optimal deposition condition. The characterization result suggests that the particles were deposited in the form of droplets with various particle sizes. Based on an analytical study, it was found that the Oxygen Partial Pressure was the most influential parameter, accounting for about 47.64% of the contribution, followed by Laser Energy (26.76%), Substrate Temperature (18.35%) and Coating Duration (6.98%), which were the least influential parameters on the surface roughness produced by HA coating. A cell line study was carried out on different surface roughness values obtained, and based on cell growth, an optimal surface roughness was predicted. The favourable surface roughness predicted by the Taguchi method was around Ra = 403 nm, whereas based on cell line studies, it was predicted around Ra = 384 nm. From both the experimental and simulation results, it is suggested that the surface roughness range of 384 to 403 nm offers better cell viability.