Multi-objective optimization of solvent cast 3D printing process parameters for fabrication of biodegradable composite stents

A solvent cast 3D printing (SC-3DP) technique was explored comprehensively to fabricate bioresorbable polymer matrix composite stent in the present study. The developed methodology was assessed by printing the customized shape stent on the rotating mandrel. The polymeric composite was developed by blending bioresorbable carbonyl iron powder (CIP) and polycaprolactone (PCL). The process parameter’s effect on percentage shrinkage in strut width and strut thickness, radial compression load and flexibility of stents was evaluated. Response surface methodology (RSM) was used for designing the experiments utilizing the process parameters like material compositions, printing speed and layer thickness. Analysis of variance was used to find out the significant parameters. The regression analysis was performed to obtain statistical equations with significant terms. It was noted that the reinforcement of CIP improved the fluidity of the material for better deposition as compared to pure PCL. The printing speed and layer thickness were observed to have a significant effect on the process. The significant interaction between layer thickness and printing speed parameters was also observed for shrinkage in width and thickness, compression and flexibility properties. Moreover, multi-objective optimization was performed using a genetic algorithm technique to minimize the percentage shrinkage of strut width and thickness, and load for bending to evaluate flexibility and maximize radial compression load. The method opens a unique way to fabricate patient-specific bioresorbable composite stents with customized properties.