Micro-texturing of molds via Stereolithography for the fabrication of medical components

The effects of micro texturing on several surface characteristics, i.e. biofouling, wetting, lubrication, cell adhesion, have been widely investigated. In the healthcare sector, and specifically medical devices, micro-structured surfaces are exploited to improve tribological properties or foster the osseointegration of surgical implants. Polymeric components in joint implants substitute cartilages of natural joints guaranteeing biocompatibility, low friction and wear, high load bearing capacity, impact strength and stiffness. Among these, tribological properties are very important for their direct impact on the implant lifespan. Micro-structuring of on-contact sliding surfaces can drastically reduce the friction and wear by promoting hydrostatic friction due to synovial fluid at the components interface. In these applications, Ultra-High Molecular Weight Polyethylene (UHMWPE) is a successful material but its current manufacturing process hinders surface micro-texturing. In this scenario, a production process chain, combining micro-injection molding of UHMWPE with molds made by Stereolithography (SLA) can be a successful option for investigating several micro-structuring designs reducing time and cost for the analysis. In this work, the micro-texturing surface manufacturing capability of an SLA technology is investigated through four micro-textures, two mold materials, three orientations in 3Dprinting and two micro-features heights. Micro-texturing patterns are realized and characterized on the molds. The same molds are then used for injection molding of parts, studying the process parameters and the replication capability on molded samples. The results show that dimension of the micro-textures brings the SLA to its limit, with good agreement on pin height and an error on the pin diameter between 24 and 108?m. The 3Dprinting orientation can improve both pin shape and surface roughness. The injection molding experimentation allows to obtain a good replication capability.