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[Display omitted] • Flexible resins, TPU and TPE materials have been investigated, fabricated with SLA, FFF and SLS AM technologies. • Effects of ethanol and chlorine solution on the mechanical properties and structure were determined. • A cell viability assay was used to test the release of toxic and harmful substances from the material. • The most noticeable changes occurred in Flexfill TPE 90A (FFF) after surface disinfection. • Flexible materials printed with additive manufacturing have potential medical applications. 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. [ABSTRACT FROM AUTHOR]

[Display omitted] • Proper sterilization and disinfection is essential in biomedical-related AM. • PLA, ABS, PETG, ABS, HIPS polyamide, and resins were investigated. • Effects of chlorine, ethanol, H 2 O 2 , autoclave, and dry heat were evaluated. • Changes in mechanical behavior and structure were analyzed. • Microbiological tests and cell viability tests were performed. Continuous development of additive manufacturing technologies has reached new areas, including medical research and healthcare applications, where precision, highly accurate reproducibility, disinfection, or even sterility of the end product is essential. The study aims to critically evaluate the effect of different sterilization and disinfection methods for most commonly used additive manufacturing technologies and materials in medical device development: PLA (polylactic acid), PETG (polyethylene terephthalate glycol), ABS (acrylonitrile butadiene styrene), and HIPS (high impact polystyrene) for material extrusion technology (FFF; fused filament fabrication), polyamide (PA2200) for powder bed fusion technology (SLS; selective laser sintering), MED610™ for PolyJet™ material jetting, and standard Formlabs™ white resin (V4) for SLA (stereolithography) technology. The materials were tested before and after different sterilization and disinfection protocols, including treatment with 70% ethanol, chlorine solution, H 2 O 2 plasma sterilization, autoclave and dry heat sterilization, applying 10 and 20 cycles in all cases. Bacteriostatic/fungistatic and sterility tests were performed using Escherichia coli , Enterococcus faecalis, and Candida albicans as reference strains. Cytotoxicity was evaluated using A549 cells. The samples showed significant structural or aesthetic alterations detected by various mechanical tests, scanning electron microscopy, or differential scanning calorimetry (DSC-TGA). No significant cytotoxic effect was revealed during the experiment. Our results can serve as a guide for the selection of effective sterilization and disinfection methods for the most common materials used in 3D printing in medical and healthcare applications. [ABSTRACT FROM AUTHOR]