Bespoke biotech

Additive manufacturing and 3D printing technology have a lot to offer makers of biomedical devices.

They were a perfect match: dental appliance company Oventus had a problem in need of a solution and CSIRO’s Lab 22 had the solution on hand just waiting for a problem to show up.

Oventus’s idea was for a new device to combat sleep apnoea, a disorder that occurs when breathing is disrupted during sleep. Sleep apnoea is a surprisingly prevalent disorder affecting around one million Australians and has been linked to insomnia, cardiovascular disease, diabetes and a slew of other ill health effects.

Existing appliances that seek to treat the disorder by improving airflow through to the back of the throat have suffered from being overly cumbersome or uncomfortable.

Oventus’s idea was for a slim new device that would aid breathing while being unobtrusive enough that it wouldn’t further disrupt sleep. The inventor, Dr Chris Hart, imagined a device in the form of a U-shaped mouthpiece that sits between the teeth and opens a pathway for air to reach the back of the throat unimpeded.

It was a simple enough concept, but the design proved challenging for traditional manufacturing. This was in part because Oventus demanded the device be as slim as possible so it could be light and comfortable to wear yet sturdy and durable enough to last. Also, because each mouth is different, it had to be tailored to each patient.

Mass production and bespoke devices aren’t typically a good fit.

So, Oventus turned to the rising star of unconventional manufacturing: 3D printing. Specifically, they engaged CSIRO’s Lab 22, which was established in 2011 to develop the technology and to engage with industry to put it into practice. Teaming up with Oventus proved to be the perfect opportunity to show off what 3D printing is capable of right now.

Layer upon layer

3D printing is straightforward in concept but revolutionary in its potential. While there are many individual 3D printing technologies, what they all have in common is that they build objects one layer at a time.

Typically, the process starts with a computer aided design (CAD) file, which is a three-dimensional representation of the object you want to create. This can be designed from scratch or derived from a 3D scan of an existing object.

The object is then digitally sliced into thin horizontal cross-sections and the CAD file uploaded into the 3D printer. The material - commonly plastic, although metals and ceramics are increasingly being used - is then loaded into the printer in a fine powdered form.

In the case of the Arcam 3D printer at Lab 22, an electron beam scans across the surface of titanium powder in the pattern of the topmost cross-section. This precisely melts the tiny pellets in the powder, bonding them together to form a solid. This thin slice of the object is then lowered and another layer of powder carefully raked across the top. The electron beam then repeats the process for each layer, lowering them one by one and covering them with more powder. Finally, the excess of loose powder is blown away - to be re-used in future print runs - and only the finished object remains.

Additive manufacturing

The last decade has seen something of a Cambrian explosion of 3D printing technologies using a wide variety of approaches and materials.

Many technologies use the same powdered-bed technique as Arcam, but others take different approaches. For example, Lab 22 also operates a cold-spray machine, which shoots a fine stream of metal particles at ultrahigh speed towards a surface. When they impact the surface they form a metallurgical bond, building up layer upon layer.

According to John Barnes, who holds the exciting title of Titanium Technologies Theme Leader at CSIRO, it is not likely that any one approach to 3D printing will end up dominating. Instead, each technology and every material has its strengths and weaknesses. Some are better at producing fine detail, while others can build things faster, while other printers can use multiple different materials simultaneously.

“It’s a bit like asking someone whether you should buy a truck or a car,” he says. “It really depends on what you want to do. If you run a moving company, you should buy a truck, but if you want to commute you should buy a car.” The key, he says, is in picking the right technology for the job.

Another term you might hear a lot is ‘additive manufacturing’, which Chad Henry, Additive Manufacturing Operations Manager at Lab 22, points out is best conceived as the overall process that has 3D printing at its core.

“Additive manufacturing incorporates all the steps, including making the input material, designing the right file, uploading that file into the machine, the post processing and things like non-destructive inspection and heat treatment. All of that is additive manufacturing. 3D printing is just the printing step,” said Henry.

Printer power

Traditional manufacturing processes, such as forging, casting or extrusion, are ideal for mass-producing thousands of identical objects, although they have their limitations. Often design is constrained by the minimum possible thickness of parts, or an inability to vary thickness throughout the object as required. Other limitations include the kinds of complex structures that can be cast, or the level of detail that can be built into or onto an object.

Also, traditional manufacturing is relatively inflexible: if you wanted to make a lot of slightly different products, or a very short run of identical objects, then you often had to turn to handmade pieces, which could end up being prohibitively expensive. This is precisely the hurdle that Oventus ran into. It wanted to be able to produce a mouthpiece that was thinner than most traditional manufacturers could handle, and it wanted each mouthpiece to be individually tailored to its user.

One of the areas where 3D printing shines is in customisability, said Barnes. All you need to do is tweak the CAD file and print out your one-of-a-kind object. In fact, you can create a couple of dozen unique objects in a single print run.

This kind of customisability was precisely what Oventus needed for its mouthpiece. After taking moulds of its patient’s mouths, it can tweak each device to suit.

“That’s a unique attribute of the 3D printing technology that enables something to exist where it would have otherwise been cost prohibitive,” said Barnes.

3D printing also enables a greater level of detail than can be achieved with other manufacturing methods, such as injection moulding. One of the challenges with the Oventus mouthpiece, for example, was the complex internal structure.

“If you look at the device itself, it has a hollow channel running through it in the shape of a T on its side. That’s where the teeth rest. Having that channel is essential to having the device work, as it allows the air to come in through the mouth, bypass the tongue and teeth, and move directly to the back of the throat.

“It seems simple - you just want a hollow channel - but how do you make a hollow channel in a U-shaped piece with an oval opening to it? That’s not an easy thing to manufacture,” he recounted.

Adding to this was Oventus’s desire for the mouthpiece to be as thin as possible, which made titanium an attractive material. With Lab 22’s expertise in 3D printing and particularly in titanium materials, all of these stringent requirements could be met, and be done economically.

Low volume, high complexity

There is currently a groundswell of biomedical device vendors actively exploring additive manufacturing for a wide range of applications.

Ben Batagol is the business development manager for Amaero Engineering, which was spun out of Monash University to handle requests from the private sector to use its 3D printing machines.

“We’ve had a lot of interest from the dental space - dentures, copings, implants, bridges - all things that have traditionally been made by hand in a dental laboratory. Every part is tailored to a patient and it fits very nicely into additive manufacturing, where you can quickly print 10 patients’ worth of parts in one job.”

Batagol’s customers often want low volumes of highly complex parts, which have been either difficult to make or prohibitively costly using traditional manufacturing techniques.

“We’ve got a range of customers who are doing parts by traditional methods, and they’re finding the process can be very expensive for low volumes, and they have high failure rates for very complex parts. They often had a lead time of over 12 months, whereas we were able to manufacture that part in a matter of days, and could produce large volumes in a much faster and easier and customisable manner.”

Improving implants

Professor Tim Sercombe, from the University of Western Australia, has also been engaging with companies in the biomedical sector to investigate the potential of 3D printing implants such as artificial hips and cranial plates.

One feature of 3D printing that gives it an edge over conventional manufacturing techniques is the ability to make the surface of the implant porous.

“This then allows the bone to grow into the surface. With conventional manufacturing the best you can do is create a patterned surface, which allows some bone adhesion, but the porous structure will allow the bone to grow into it and give some mechanical fixation other than the screws.”

Sercombe and his colleagues are currently working with titanium to make it more suitable for 3D printed implants.

“One of the problems with titanium in the body is it’s too stiff. If you get the surface properties correct then bone will happily grow onto it and into it, but if the implant is too stiff, you run the risk of the bone dying off and the implant coming loose.”

He is currently working on a new titanium alloy developed in China that has a stiffness roughly half of conventional titanium, and he’s confident they can continue to make refinements until they reach a material that is ideal for implants.

Rewriting the rulebook

While 3D printing is changing the way biomedical products are made, it is also changing the way that designers have to think when it comes to conjuring them in the CAD program.

“3D printing requires its designers to forget about everything they’ve learnt,” said Sercombe.

“At the moment designers are having to temper their designs with concerns about manufacturability. They can’t design how they want to design because they have to make the thing at the end of the day.

“Traditional manufacturing processes put all kinds of restrictions and constraints on the kinds of geometries that can be produced. If we can convince them to forget about how you’re going to make it, and design the thing how you want to design it, and we can make it, then that changes the paradigm significantly.”

One of these limitations is the thickness that materials have to be when made with traditional manufacturing techniques.

“Designers need to move away from the idea you have a uniform thickness on all walls,” added Batagol. “If you don’t need strength in a certain area, it makes sense to remove materials.”

Additive manufacturing does have its limits. The surface finish on many 3D printed objects is not as smooth as forged or machined parts, thus requiring post processing to polish them up. 3D printers also aren’t well suited to mass production of identical objects, which can often be done far cheaper with conventional manufacturing. But 3D printing is finding a complementary role with traditional manufacturing and is likely to displace it in some areas, particularly in the biomedical space.

For companies like Oventus, its experiment with 3D printing has proven to be a boon. It has been very pleased with the collaboration with Lab 22 and is currently on track to have its custom titanium sleep apnoea device ready for sale to patients in 2015. It may not be long before other biomedical device companies are also breathing easier thanks to the power of 3D printing.

Professor Tim Sercombe received his PhD from the University of Queensland (UQ), where he first explored 3D printing using aluminium. He continued this research as a postdoc in the University of Birmingham in the UK before returning to UQ in 2001. In 2006, he moved to the University of Western Australia, where he started looking at 3D printing using titanium, particularly for biomedical applications.

Ben Batagol has a Bachelor of Business from Monash University and is currently studying a master’s in project management through the University of South Australia. He has worked in the defence industry for over 12 years. In 2014 he joined Amero Engineering, which was spun out of Monash University, as Business Development Manager.

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