Design and functionalisation of shoe outsoles with antimicrobial properties using additive manufacturing technologies: industrial applications

Cross-contamination by people movement is a serious problem in food and health environments. This is caused by the need for workers to move around different areas of the workspace, carrying bacterial agents in their shoes from one place to another. The disinfection methods commonly used do not completely eliminate the microorganisms, mainly due to the porous structure of the outsole of the footwear used. This document presents a new prototype of functional footwear for these environments, whose outsole design has been functionalised in such a way that it is presented through two independent fundamental elements: a main body made of EVA by injection; and a footprint, in direct contact with the pavement, which can be exchanged for another pathogen-free footprint when deemed necessary, avoiding the transfer of microorganisms when the user moves from one place to another. This footprint is manufactured by fused-filament 3D printing, using thermoplastic polyurethane (TPU) material additivated with silver nanoparticles (AgNPs), which give it antimicrobial properties. The industrial design of these two elements has been carried out with the aim of guaranteeing a solid attachment between them, but at the same time allowing the replacement of footprints in a simple and fast way, and without requiring the use of additional auxiliary elements. Through the experimentation phase, the antimicrobial and cytotoxic properties of the developed footprint have been analysed, and the physical-mechanical properties of the footprint as a whole have been evaluated according to various standards. (C) 2020 Elsevier B.V. All rights reserved.