Just what the doctor ordered!

Additive manufacturing has been identified by many as a game changing technology. But while it does clearly have limitations, there are those who are experimenting with the possibilities - and in the case of medical manufacturer Owen Mumford it has completely transformed the prototyping process.

Medical device design comes with a unique set of problems. High on this list would be product usability for patients of vastly varying ability levels, limited material options, the drive for self monitoring/medicating and of course the regulatory framework around it. Such challenges are all in a day’s work for Owen Mumford, a company that specialises in drug delivery and blood sampling devices and who have formed partnerships with most of the world’s leading pharmaceutical companies.

“In order to remain in that kind of market we need to innovate,” claimed Andy Varde, director of research and development at Owen Mumford. “As a result of that, we have about 130 active patents filed or granted and about 600 patent families across the world to use as our IP portfolio.” One product based on such IP was the world’s first automatic insulin pen, and this captures the essence of the recent trend for self-administered medication, often requiring the device to be both simple and disposable.

“Human factors are critical in this space - user-centred design is really important to us,” continued Varde “The needs of a patient with multiple sclerosis are very different from the needs of a patient with rheumatoid arthritis, for example, or some other differences in terms of dexterity, or vision, or side implications of the disease itself.”

It means there is significant input at all stages of the design process from a number of stakeholders, which includes user groups and clinical experts organised in structured studies to resolve particular issues, and the consequence is products that first and foremost fulfil a need. Varde explained: “Innovation is an interesting thing to define, but for me, it's bringing something to the world that makes a difference and has value in some way in that market. There is tremendous virtue in medical devices in simplicity. Devices need to be utterly easy and simple to use. They need to give the user what they need, they need to give it exactly at the time that they need it, and they need to help them as far as possible. They mustn't confuse.”

Simplicity in innovation is not easy to achieve, particularly in such an iterative design process with so many people involved. But Owen Mumford has changed its whole prototyping strategy to make it a reality, and 3D printing was the enabling technology.

3D printers are increasingly used in industry as part of the product development process, but their use is restricted by the materials that can be used on them. Particularly in the medical environment, if the prototype is to be used in any trials involving humans or a drug which they are going to come in contact with, the materials used in the prototype need to be the same as those that would be used in the end product. Such medically-approved materials are not yet widely available for 3D printing.

Until two years ago Owen Mumford outsourced all of its prototyping, using a variety of techniques – like 3D printing, injection moulding, CNC machining and metal fabrication – as each application demanded. Toby Cowe, technology development group manager, explained the approach when it was important to get components made in the correct materials: “Three years ago we would go to a soft tool manufacturer. That would have cost round about £4000 to £6000, and it would have taken two to six weeks to make a tool.”

It may have been accepted industry practice and timescales, but it was not helping the company meet its prototyping schedules. Varde started investigating the potential of buying a 3D printer outright. “We looked very carefully at what the cost benefit of doing it was, and they were really quite significant. We saved the money back we were spending on prototyping within about 12 months. The printer actually exceeded our expectations, in terms of how it assisted us. We were expecting to get about 50% reduction in our outsourcing of our prototyping work, and we've achieved about a 95% reduction.”

The machine selected was the Objet 260 from Stratasys, selected at the time because Varde and Cowe believed it to be the most accurate on the market with resolution of 16um. As stated before, even with high quality printing at their disposal, printing prototype parts was of limited use. “Direct 3D printing can be suitable for dental applications or potentially surgical applications, but when you're looking at high volume products such as lancing devices or drug delivery devices, the inherent variability and weakness of the materials that are currently available from 3D printing would introduce risk and significant cost to the product as well. So we are using the 3D printer to create tools with which we can then use whatever material we want.”

With an injection moulding machine sitting alongside the 3D printer in the lab, prototypes are thus produced overnight, in end product materials, without the lengthy and costly procedure of having to outsource the tool design.

Cowe’s team has taken the process one step further by standardising the insert sizes. A metal bolster holds the insert (the tool) which can be of two standard sizes 70 x 70mm or 140 x 230mm. This simple innovation has opened up usage of the printer to the whole design team. Varde commented: “If it had been just left ad hoc everybody would have to reinvent the wheel every time they were trying to do something. This way all they have to worry about is getting the cavity right and then the rest of it is all predetermined. That's what makes it so much easier and faster to use as a prototyping tool for a wider group of people.”

It has made the whole design and prototyping process far more dynamic, as Varde explains: “We can do three iterations in three days rather than three months. Our ability to fail early is improved by having the technology. So there's been not only the tangible benefits, the reduction in cost of paying to outsource the prototyping, but we've also had the added benefit of dramatically increasing the speed of our ability to prototype quickly and fail early, and also our ability to then change what the design is, based on our understanding of what we get from those prototypes.”

And such has been the success that Varde is considering expanding the 3D printing capability. “We are considering maybe having one or two lower end machines - more your kind of desktop type of machine - just to give another string to our bow, to do very quick representational models. There are some relatively small machines now for £1500 that can produce some relatively passable representational models, just to get some early ideas.”

The Stratasys Objet 260 Connex printer features dual jetting technology, which allows the use of ‘digital materials’ – combining two base resins in specific concentrations to provide a whole range of materials of certain hardness, opacity, flexibility or thermal properties. Build size is 255 x 252 x 200mm and the layers (i.e. the resolution) is 16 microns.

Describing the choice of the Objet 260, Varde said; “But we had a look across the board at various technologies and this was one that I think for us, for our particular needs, was head and shoulders above some of the others.”