Surface disinfection change the mechanical, structural and biological properties of flexible materials used for additive manufacturing of medical devices

Additive manufacturing (AM) is a versatile technology with potential applications in healthcare and medical instruments, where surface disinfection or sterilization is essential. This study comprehensively the effect of commonly used cost-effective disinfectants, ethanol (70 V/V%) and chlorine solution on the mechanical and thermal properties of flexible 3D printed materials. The following materials were tested before and after a 5 -cycle surface disinfection: Flexfill TPE 90A, Phyton Flex (TPU) for material extrusion, Flexible (resin), Elastic 50A (resin) for vat photopolymerization and Flexa Black (TPU) material for powder bed fusion technology. Mechanical tests included tensile, compression, Charpy impact, flex resistance and stress relaxation tests, as well as Shore A hardness and volume measurements. The structure was analyzed using scanning electron microscopy (SEM)and Raman spectroscopy. The cytotoxicity was assessed using a A549 cell viability assay. The results show that after disinfection, significant changes occurred mainly in the tensile and Shore A properties, such as the tensile strength of the disinfected Flexible (resin) materials was 3.44 MPa +/- 0.51 MPa (ethanol) and 2.62 MPa +/- 0.31 MPa compared to the native 2.02 MPa +/- 0.24 MPa. Interestingly, the applied surface disinfectants can negatively affect biocompatibility. Medical devices have been designed and fabricated based on the findings. Our findings can serve as a guide to the potential applications of commonly used 3D printed flexible materials in the biomedical field.