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How 3D printing is disrupting medical device design

07 March 2017

3D printing is transforming the medical field, from surgical instruments and skeletal reconstruction, to medical devices and anatomical models.

Cardioplegia clamp

It is becoming increasingly clear that it is part of the future of patient treatment, for more than just complex procedures - it’s fast becoming part of the everyday as it matures and costs continue to fall. 

Government pressure to improve the quality of patient care while still reducing costs, has prompted some health trusts to search for solutions that are bespoke, yet affordable. One area that 3D printing is helping to transform is the high volume medical device market such as the specialist clamps and instrument holders typically found in operating theatres. These are being replaced with bespoke solutions that are not only cost effective and easy to use, but can be developed in a fraction of the time to provide a far cleaner and safer environment – helping to save lives.

A bespoke 3D printed cardioplegia clamp

Bennett Engineering Design Solutions were approached by a health trust, late last year to help develop a bespoke solution to support the use of cardioplegia sets in its operating theatres. 

The Trust had been pleased with the quality of a pressure gauge holder developed previously by the design team and wanted a clamp based on similar principles.

John Bennett, director, Bennett Engineering Design Solutions, explains that the clamps that were available at the time for holding the cardioplegia set’s heat exchangers, which cool down the patient’s blood during cardiac surgery, were no longer meeting the Trust’s requirements. The clamps simply didn’t secure the heat exchangers well enough, they could also be slow and difficult to use.

The Trust required a complete design rethink; it needed a solution that would attach easily to standard masts and instrument stands as the heat exchanger must be quickly changed in an emergency. The unit needed to be easy to clean and suitable for sterilisation. It must also be possible to adjust the orientation of the heat exchanger through 360° so blood can run without interruption and the set’s tubes not be strained.

John Bennett notes that the challenge with the design was to create the right geometry to satisfy the Trust’s requirements. The initial prototype needed to be improved to make the changeover quicker. Adjusting the geometry of the catch took two iterations and Bennett also needed to minimise the number of parts required, to ensure ease of use while being aesthetically pleasing. The clamp for example, features an over centre clip finger for the attachment so the removal of the heat exchanger is simple and intuitive to use. 

Bennett chose to develop the design using 3D printing as it believed it offered greater flexibility on the design geometry, enabling the creation of more organic shapes. This was then followed by the material Alumide, to deliver a tough, highly professional ‘look and feel’ to the end product.

Alumide is a very versatile material due to its composition, nylon and grey aluminium powder. It provides both lightness and strength; is cost effective to print and can be sealed for cleaning and sterilisation - ideal for certain types of medical equipment.

The completed design used standard components along with 3D printed parts to achieve a simple and cost effective solution. By adopting 3D printing, complicated geometry and shapes could be included at no extra cost, allowing the design team far greater design freedom to deliver improved aesthetics. 

No manufacturing tools were required, which helped to ease this critical design update and change of parts during the product development process, which took just eight weeks to complete and has been in use by the Trust since June 2016. It now benefits from a bespoke design solution, rather than the generic clamps produced in high volume by heat exchanger manufacturers.

The cardioplegia clamp, although a bespoke design can also be adapted to be used in any operating theatre by the team at Bennett Engineering Design Solutions. 

3D printing promises to deliver greater flexibility for design engineers, by decreasing wastage in design, eliminating tooling and lowering life-cycle costs. This combined with the recent maturity of the 3D printing process, with advanced materials, printer and innovations means the technology is now ready to develop new medical devices that were previously either too difficult or expensive to create.

3D printed mitral valve model for pre-surgery planning

The design team has recently been approached by another health trust to engineer bespoke parts for medical research, including the development of research equipment for testing the feasibility of a proposed new mitral valve intervention.  

The equipment holds and tests valves that have been made to simulate diseased ones and then repeats the tests with the proposed interventions in place. Pressure and flow are measured to prove that the valve is being tested at realistic conditions. Additionally, because the valves are tested with forward and reverse flow, their ability to seal and minimise regurgitation can be checked and quantified. This is the very first step to proving if the intervention is feasible.

A further benefit that was designed into the equipment, is that is allows almost any artificial Tricusp valve to be demonstrated and tested along similar lines to the mitral valve. The need for many different tube connections meant that it was the perfect project for additive manufacturing.

The proposed solution combines standard medical components and 3D printed parts of different materials as well as a metal mounting panel to provide a compact and neat tool with all the necessary features built in.

The future

John Bennett concludes that the bespoke medical devices that Bennett have designed are making a difference already. They are helping to provide cleaner and safer operating theatres through more efficient ergonomic design that aids sterilisation and saves precious time. This however, is just the periphery of what can be achieved.

Great strides have been taken in recent years, leading to both biological (the ability to print living tissues) and artificial 3D printing applications for bone, arteries, skin and even organs. This growth will transform the medical sector, providing new biological advances right through to improvements on a smaller scale, in the busy operating theatres where mass produced devices are increasingly being customised to deliver healthcare improvements.

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