The Rise of 3D Printed Prosthetic Eyes

Recently there’s been quite a lot of attention on the use of 3D printing to manufacture artificial eyes (aka. ocular prostheses). This has largely been due to an announcement out of the UK that the world’s first 3D printed artificial eye was implanted in a patient.

Quite a cool milestone and application of 3D printing, and also happens to be a field I’ve been investigating for the past 6 months with some of my colleagues at the Herston Biofabrication Institute. We’ve just published a review of all research into the use of 3D printing for orbital and ocular prostheses, and you can access the full article for free here.

The graph above does a nice job of showing the overall trend for research on this topic, with the first ever paper dating back to 2004. Early studies like this certainly weren’t 3D printing eyes and implanting them in patients, but instead used 3D printing as part of the process, creating moulds and similar devices. The first time a 3D printed part was directly used as part of a prosthesis was in 2014.

Perhaps one of the best ways to demonstrate what is possible now using full-colour 3D print methods (material jetting) is the below video from Weta Workshop. While these may be eyes for monsters, the same principle is being used for human prosthetic eyes. One of the key differences between what Weta Workshop have achieved, and what is being done for patients, is the need for biocompatible materials, as well as the need for a patient’s eye to perfectly match their existing “good” eye.

While it’s early days in the clinical trial phase of implementing 3D printing for prosthetic eyes, there are many benefits which we summarised from our research, including:

• Manual steps in prosthesis fabrication can be replaced by digital methods, potentially saving time
• Less discomfort to patients through use of medical imaging or 3D scanning techniques
• Weight reduction compared to traditional methods
• Improved accuracy and fitting of prosthesis
• Minimised need for gluing a prosthesis to the skin
• Good realism of eye
• Ability to easily re-print the same components in the future

Of course, there are currently some limitations as well, such as:

• End-use 3D printed parts are typically not biocompatible and require coating with PMMA or used as a mould to cast with biocompatible material (although the UK trial shows that direct 3D printing of multi-colour biocompatible materials may be possible)
• Experience in computer-aided design (CAD) technology is required, which is not part of traditional skillset for prosthetist
• AM times are slow (although they can also happen overnight or while a specialist does other things)
• Rough surface quality of parts requires additional post-processing e.g. polishing
• Challenges associated with using 3D scanners e.g. patient movement or scanning anatomy with hair
• Expert manual skills are still required for some steps of the workflow
• Use of CT scanning for the purposes of creating a prosthetic increases patient exposure to potentially harmful radiation

Research to-date has been limited to small case studies and engineering experiments, making it difficult to understand whether outcomes will translate to the clinical context. It will be great to see how the UK clinical trial progresses, and hopefully provides improved outcomes for patients. Let’s watch this space!

– Posted by James Novak

From bespoke seats to titanium arms, 3D printing is helping Paralympians gain an edge

Jeff Crow/AAP Image

Authors: James Novak, The University of Queensland | Andrew Novak, The University of Technology Sydney

** Please note: this is a copy of an article I wrote for The Conversation, published on 3rd September, 2021, and is shared under a CC-BY-ND license. You can access the original article by clicking here.**

Major sporting events like the Paralympics are a breeding ground for technological innovation. Athletes, coaches, designers, engineers and sports scientists are constantly looking for the next improvement that will give them the edge. Over the past decade, 3D printing has become a tool to drive improvements in sports like running and cycling, and is increasingly used by paralympic athletes.

The Paralympics features athletes with a diverse range of abilities, competing in a wide range of different categories. Many competitors use prosthetics, wheelchairs or other specialised components to enable them to perform at their best.

One interesting question is whether 3D printing widens or narrows the divide between athletes with access to specialised technologies, and those without. To put it another way, does the widespread availability of 3D printers — which can now be found in many homes, schools, universities and makerspaces — help to level the playing field?

Forget mass production

Mass-manufactured equipment, such as gloves, shoes and bicycles, is generally designed to suit typical able-bodied body shapes and playing styles. As such, it may not be suitable for many paralympians. But one-off, bespoke equipment is expensive and time-consuming to produce. This can limit access for some athletes, or require them to come up with their own “do-it-yourself” solutions, which may not be as advanced as professionally produced equipment.

3D printing can deliver bespoke equipment at a more affordable price. Several former paralympians, such as British triathlete Joe Townsend and US track athlete Arielle Rausin, now use 3D printing to create personalised gloves for themselves and their fellow wheelchair athletes. These gloves fit as if they were moulded over the athlete’s hands, and can be printed in different materials for different conditions. For example, Townsend uses stiff materials for maximum performance in competition, and softer gloves for training that are comfortable and less likely to cause injury.

3D-printed gloves are inexpensive, rapidly produced, and can be reprinted whenever they break. Because the design is digital, just like a photo or video, it can be modified based on the athlete’s feedback, or even sent to the nearest 3D printer when parts are urgently needed.

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Read more: Paralympians still don’t get the kind of media attention they deserve as elite athletes

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Harder, better, faster, stronger

An elite athlete might be concerned about whether 3D-printed parts will be strong enough to withstand the required performance demands. Fortunately, materials for 3D printing have come a long way, with many 3D printing companies developing their own formulas to suit applications in various industries – from medical to aerospace.

Back in 2016, we saw the first 3D-printed prosthetic leg used in the Paralympics by German track cyclist Denise Schindler. Made of polycarbonate, it was lighter than her previous carbon-fibre prosthetic, but just as strong and better-fitting.

With research showing sprint cyclists can generate more than 1,000 Newtons of force during acceleration (the same force you would feel if a 100-kilogram person were to stand on top of you!), such prosthetics need to be incredibly strong and durable. Schindler’s helped her win a bronze medal at the Tokyo games.

Denise Schindler on her way to a medal in Tokyo. Thomas Lovelock

More advanced materials being 3D printed for Paralympic equipment include carbon fibre, with Townsend using it to produce the perfect crank arms for his handbike. 3D printing allows reinforced carbon fibre to be placed exactly where it is needed to improve the stiffness of a part, while remaining lightweight. This results in a better-performing part than one made from aluminium.

3D-printed titanium is also being used for custom prosthetic arms, such as those that allow New Zealand paralympian Anna Grimaldi to securely grip 50kg weights, in a way a standard prosthetic couldn’t achieve.

Different technologies working together

For 3D printing to deliver maximum results, it needs to be used in conjunction with other technologies. For example, 3D scanning is often an important part of the design process, using a collection of photographs, or dedicated 3D scanners, to digitise part of an athlete’s body.

Such technology has been used to 3D-scan a seat mould for Australian wheelchair tennis champion Dylan Alcott, allowing engineers to manufacture a seat that gives him maximum comfort, stability and performance.

3D scanning was also used to create the perfect-fitting grip for Australian archer Taymon Kenton-Smith, who was born with a partial left hand. The grip was then 3D-printed in both hard and soft materials at the Australian Institute of Sport, providing a more reliable bow grip with shock-absorbing abilities. If the grip breaks, an identical one can be easily reprinted, rather than relying on someone to hand-craft a new one that might have slight variations and take a long time to produce.

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Read more: 3 reasons why Paralympic powerlifters shift seemingly impossible weights

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All these technologies are increasingly accessible, meaning more non-elite athletes can experiment with unique parts. Amateurs and professionals alike can already buy running shoes with 3D-printed soles, and 3D-printed custom bike frames. For those with access to their own 3D printer, surf fins, cycling accessories and more can be downloaded for free and printed for just a few dollars.

However, don’t expect your home 3D printer to be making titanium parts anytime soon. While the technology is levelling the playing field to a certain extent, elite athletes still have access to specialised materials and engineering expertise, giving them the technological edge.

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This article was co-authored by Julian Chua, a sports technology consultant at ReEngineering Labs and author of the Sports Technology Blog.

3D Printed Flexible Lens Cover

I’ve said it countless times before, and I’ll say it again – some of my favourite 3D printing projects are the ones which are quick, easy, and either add value to an existing product (e.g. see my 3D printed webcam mount or lucky bamboo holder), replace something broken or lost (e.g. my SUP paddle lock),  or in this case, something missing.

I recently bought an old pair of binoculars (or is it just a binocular?) from an antique store. They came in a pretty beaten up case, and were missing two of the protective lens covers, but overall worked nicely with lenses that weren’t scratched. The lens covers that did come with the binocular were cracking and didn’t really stay in place any more, so it was 3D printing to the rescue.

Planning to use some PolyFlex TPU95 filament from Polymaker to create a soft, rubber-like lens cover, I ended up designing the lens covers to be just slightly smaller than the measured diameter of each lens, 0.25mm smaller to be specific, with the intent of creating a secure friction fit, but not so tight they had to be stretched over the lenses. The design is very simple, a couple of extrudes in Fusion 360, before adding the circular pattern detail around the outside (which was not part of the original lens caps!) to add a personal touch. Now that they’re printed they remind me of beer bottle caps, but the intent was just something a bit rugged and easy to grip without spending a long time trying to be too clever in CAD.

These were 3D printed on a Wanaho Duplicator i3 Plus with an upgraded Flexion Extruder. What’s a Flexion Extruder? Well, you can read my whole series documenting early experiments trying to 3D print flexible materials here, but long story short, a Flexion Extruder is the ultimate upgrade for cheap desktop FDM machines that allows you to successfully and reliably 3D print with soft TPU materials. If you don’t have a Flexion, or a good quality system like the Prusa MK3S which has been designed to print a whole range of materials including TPU, chances are you will end up with a tangled mess of filament coming out the side of your extruder, or worse! They’re just too soft to be forced down into the hotend and come out of a tiny nozzle.

The other trick is getting the right settings to print with – you will find loads of different theories and recommendations online, 3D printing TPU is a bit of a dark art and there are many different types of flexible TPU that require different settings. So getting things right will take some time. This is a good general guide to follow, and I’d reiterate that you MUST print extremely slow – I used 20mm/s for the lens caps. Also, follow the recommendations from your filament supplier, this material from Polymaker was printed at 220°C with the build plate at 50°C. Seemed to be about perfect.

Above you can see just how flexible the end result is, the lens caps easily bend and squash without permanent deformation. If you’ve got any settings you’ve found are reliable, or just general tips and tricks for 3D printing TPU, please comment below to build up some resources for others to find.

Happy 3D printing.

– Posted by James Novak

Motorbike Indicator Adapters

An issue with owning an older (well 2007 isn’t really that old!) motorcycle is that finding parts gets harder and harder. The previous 3D prints for my bike (such as rear peg plugs, key guard and mirror plugs) have really just been cosmetic, but after buying some sleek little LED indicators to replace the huge stock ones, I came across a problem – the fitting point for the rear indicators is specific to the shape of the stock ones, which is a really large cut-out and has nowhere to install the standard indicators designed to fit most bikes. There was also nothing online I could find ready to buy. One option would be to simply drill a new hole through the plastic mud guard, but this would leave the previous holes on show and mean that if for some reason someone ever wanted to put the stock indicators back on, they would now have these new holes to deal with.

No, not on my watch! My first idea started with trying to fit something from the inside of the mud guard, plugging the hole and providing a new point to mount the LED indicators inside of this. The problem was measuring this area, with other wires and complex shapes, it became quite challenging to get any accurate measurements. Since I’ve already used the green PET+ filament on the bike, I may as well make this indicator adapter a feature, and use the flat outside face of the mud guard to easily create a paper template as shown in the top left image. This was scanned, traced in Adobe Illustrator, exported as a .dxf file, and then imported into Solidworks to create the final 3D form. This might seem like a lot of processes, but is a really accurate method of getting a starting point for 3D modeling when dealing with flat surfaces using basic equipment at home.

The final 3D print pictured was done on my new Cocoon Create using 0.2mm layer thickness and took about 55 minutes to print. While the final design looks flat, there are a few tricky details on the back used to lock it in place with only 1 screw (thankfully the mud guard had a useful threaded hole for mounting). I will now be interested to see how well the PET+ plastic holds up out on the road – it seems quite secure, and the indicators are very lightweight, but who knows what can happen out on the road.

– Posted by James Novak

UPDATE: I am now trialing the use of Sketchfab so you can easily view 3D models of my work – check it out below!

Rear Indicator Panel – Right by edditive on Sketchfab

3D Printed Wood vs. Plastic

Well here it is – my 3D printed wooden phone amplifier fresh from i.Materialise, which won their 3D printed wood challenge! Now it’s time to have your say:

Which sounds better? 3D printed wood, or 3D printed ABS plastic?

On first impressions it’s definitely a fragile material, a bit like something between MDF timber and an egg carton. The graininess can be rubbed off like sand, and you can already see one of the dots in the ‘i’ has broken off. But it smells really nice, I just can’t quite put my finger on what it reminds me of. But definitely very wood-like.

For those wanting to print one yourself, the plastic version is freely available for you to download from my Thingiverse or Pinshape profiles. This wooden one is slightly different to meet the requirements of the printing process, but I may add this to the i.Materialise shop very soon so you too can enjoy the natural sounds of timber.

– Posted by James Novak

Winner – 3D Printed Wooden Amplifier

It was a while ago now that I first 3D printed a phone amplifier and stand, sharing my design on Thingiverse (see the original design and video here). Well after seeing i.Materialise’s new wood material, and a competition to launch it, I just had to bring it back! What could be more cool than a 3D printed wooden amplifier, mixing the old-school with the new-school?

It did take some work to modify the original design to meet the criteria of the wood material, including thicker wall sections and more exaggerated details, and you can see the render I submitted above on the right. The final print from i.Materialise on the left looks awesome, I’m looking forward to hearing it play music when it arrives – I’ll have to post a video comparing the sound of the wood vs. plastic versions, so watch this space.

See the full i.Materialise article, along with the other winning designs here.

– Posted by James Novak