3D printing notes

1. . 2016; 4: e2661.

Published online 2016 Dec 1. doi: 10.7717/peerj.2661
PMCID: PMC5136128
PMID: 27920950

On the intrinsic sterility of 3D printing

One of the most important properties of basic labware in the biological sciences is sterility, and one of the most frequent questions laboratory biologists ask when they first learn of 3D printing is, “Can I autoclave these things?” Unfortunately, most thermoplastics that are widely used in biomedical applications, particularly polylactic acid (PLA) and polyglycolic acid (PGA), will not survive a standard autoclave cycle (). Sterilization with γ-radiation is effective, but causes drastic changes to the biochemical properties of the material ().1 Here we detail our work demonstrating that the 3D printing process itself appears to be sufficient for ensuring sterility.
We note that the fused deposition modeling (FDM) 3D printing process, in which a thermoplastic filament is heated to melting and forced through a narrow tube under high pressure, resembles a sort of extreme pasteurization. Figure 1 compares the FDM 3D printing to several sterilization processes (note that thermal contact time is in log scale). The 3D printing process holds the material at a higher temperature for longer duration than both Ultra-High Temperature (UTH) pasteurization, which is used to produce shelf-stable milk (138 °C for two seconds) and high-temperature, short-time (HTST) pasteurization used for dairy, juice and other beverages and liquid ingredients (71.5 °C–74 °C for 15–30 s). The only legal pasteurization method that exceeds the thermal contact time typical of FDM 3D printing is mentioned in Title 21, Sec. 1240.61 of the Code of Federal Regulations, which permits milk to be treated at 63 °C for 30 min. This is a convenient sanitation regime for milk in non-commercial settings (indicated in  Fig. 1 as “stovetop” pasteurization). 3D printing is also both hotter and longer duration than thermization, a process used to extend the shelf life of raw milk that cannot be immediately used, such as at cheese making facilities.

2. . 2018 Mar; 9(1): 17.

Published online 2018 Feb 7. doi: 10.3390/jfb9010017
PMCID: PMC5872103
PMID: 29414913

Novel Biomaterials Used in Medical 3D Printing Techniques

Table 1

Types of 3D printing technologies.
Process Principle
Extrusion Printing
Fused Deposition Modeling (FDM) [] A thermoplastic material is melted and laid on to the build platform in layer-by-layer fashion, until the object is formed.
Materials: acrylonitrile butadiene styrene (ABS), poly-lactic acid (PLA), nylon.
Bioprinting [] Biological materials are extruded through a nozzle under pressure to lay down materials in sequential layers till the scaffold is built.
Materials: alginate, chitosan, gelatin, collagen, fibrin.
Material Sintering
Selective Laser Sintering (SLS) [] A high-power laser beam fuses the powdered materials in layer-by-layer pattern to form an object.
Materials: nylon, polyamide.
Electron Beam Manufacturing (EBM) EBM is similar to SLS, except for high power electron beam is used to fuse the powdered particles.
Materials: titanium, cobalt−chrome alloy.
Stereolithography (SLA) [] A UV laser beam selectively hardens the photo-polymer resin in layers.
Each layer is solidified and built on top of next until the object is formed.
Materials: photopolymers.
Continuous Liquid Interface Production (CLIP) [] CLIP is similar to SLA, except for UV beam is passed through a transparent window at the bottom of the resin and build platform raises upwards holding the 3D printed object.
Materials: photopolymers.
Material Binding
Binder Jetting/Inkjet [] A liquid binding material is selectively dropped into the powder bed in alternative layers of powder–binding liquid–powder, until the final object is formed.
Materials: starch or gypsum (powder bed) and water (binding agent)
Polyjet Polyjet printing is similar to inkjet, but instead of binding agents, photopolymer liquid is sprayed in layers onto the build platform and is instantaneously cured using UV light.
Materials: polypropylene, polystyrene, polycarbonate.
Laminated Object Manufacturing (LOM) Layers of adhesive coated material are successively glued together and cut in required shapes using a laser.
Materials: thin sheets of paper, polyvinyl caprolactam (PVC) plastic, or metal laminates

3D printing sounds like a concept from a sci-fi movie or an Isaac Asimov novel. It involves creating a physical, three-dimensional object from a digital file. The technology has been used for some time in niche markets, generally for prototyping. However, new breakthroughs are propelling 3D printing into the mainstream, and the technology is poised to cause serious disruptions in manufacturing and healthcare.
recent PricewaterhouseCoopers survey of US manufacturers revealed that two out of three companies have already begun adopting 3D printing, from experimenting with the technology to using it to create final products. The same survey found that about 30% of manufacturers believe widespread adoption of 3D printing will revolutionize supply chains, shrinking them so that end-users get ahold of products faster, and without the need for costly.
Some of the most fascinating applications for 3D printing can be found within the healthcare industry. Already, enterprising researchers are using the technology to manufacture artificial tissue, organs, and the equipment needed to perform treatment procedures. For the field of ophthalmology, this can present tremendous benefits. A 3D printer can utilize patients’ cells to create their own transplant organs, or print intraocular cataract lenses and artificial eyes. The technology shrinks the healthcare supply chain, reducing a patient’s and clinican’s dependence on costly equipment, long turnaround times for custom devices, and even human eye donors.
The Spanish Institute for Biomedical Research, at the La Paz Hospital (Instituto de Investigación Biomédica del Hospital La Paz (IdiPAZ) in Madrid is actively working toward developing 3D printed corneas by 2022, which will deliver cost-effective and highly-customizable treatment products to patients suffering from corneal pathologies. The technology will completely eliminate the need to locate suitable human donors, saving time and the vision of many patients. Manufacturers will be able to produce the required corneas in mere days, or prosthetic eyes and spectacles at the push of a button.

3D printing technology can assist in creating more specialized ophthalmology

Equipment and products, all in a way that is faster and more cost-effective than how the current supply chain operates. As a leading provider of instruments and equipment vital to the ophthalmology industry, Accutome is excited to explore how 3D printing will shape the future of eye care. Discover more about what is happening in the ophthalmic community by subscribing to the EyeOpener today!
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