Next-generation medical devices: 3D printing with medical-grade silicone

The integration of silicones with 3D printing brings ground-breaking possibilities for personalised and more sustainable medical devices such as prostheses, anatomic models, and the latest diagnostic innovations.

A highly versatile material, medical-grade silicone is a material of choice for medical device OEMs. Estimates of the size of the global market for medical-grade silicone are reported to be US$1.6bn in 2022, following years of growth fuelled by its use in implants, drug delivery devices, prosthetics, dental tools, and other medical applications. Silicone continues to be a key pillar of innovation and is now being combined with the latest advancements in 3D printing – leading to ground-breaking patient-customised medical devices.

Also known as additive manufacturing, 3D printing creates three-dimensional objects from CAD or 3D model templates via a ‘printed’ matrix. This matrix is built up layer by layer or used to make fast prototyping moulds. It can enable the fabrication of 3D structures that are extremely complex or one-offs that are usually prohibitively expensive or impossible to produce using traditional manufacturing.

GlobalData reports that the 3D printing market is set to follow a steep growth curve, from around $19bn in 2019 to more than $60bn globally by 2030. For devices with small production runs and high precision demands, the trend is that 3D printing will increasingly replace traditional means of manufacturing.

Previous to the Covid-19 pandemic, 3D printing was already opening up many new applications in the medical sector, notably in orthopedics, creating bespoke replacement joints. During the pandemic, with materials often in short supply, the process helped with the rapid development, prototyping and manufacturing of new emergency medical devices. Moving forward, 3D printing has become one of the cornerstones of manufacturing for surgical guides, medical instruments, and other implants, including dental devices and hearing aids.

Silicones and 3D printing

Philipp Schattling, Project Leader Diagnostics and Long-Term Medical Implants at Elkem Silicones, one of the world’s leading, fully integrated silicone manufacturers, is a keen proponent of using silicone in 3D printing for medical devices, both structural and diagnostic. He says that previous manufacturing methods only had two states, prototyping and mass manufacturing, with nothing in-between. 3D printing is the process that can fill that gap, and silicone is perfect to work with this innovative technology.

The latest diagnostic devices include microfluidics – miniaturised devices that manipulate the behaviour of a fluid through a series of reagents, sometimes referred to as ‘lab-on-a-chip.’ Schattling explains how this kind of innovative device can benefit from 3D printing: “You can use 3D printing of silicone to 3D print the microfluidic structures. This is an emerging trend, at least for medium volume microfluidic devices. You basically 3D print the cartridge of the microfluidic device.”

Often in short supply during the pandemic, nasal swabs are one example of how 3D printing can help with emergencies and shortages. Once regulatory agencies approved the use of 3D printing for mass production, companies were able to quickly print nasal swabs for use during the outbreak. Silicone is used on the very tip to help collect the sample from the nasal passage.

Bob Waitt, Global Marketing Manager for Elkem Silicones, explains how 3D printing using silicones is also perfect for anatomical modelling: “This is where a doctor will take a scan of an organ, such as the oesophagus, and replicate it using a 3D printer. They typically use silicone to create the anatomical models. This then enables them to perform a practice procedure and work with the model in their hands, so they can determine what the best approach will be to address the issue.”

Lighter liners and a better fit

3D printing with silicone materials enables clinicians to create lighter devices that have equal or superior mechanical properties compared to standard manufacturing methods, due to the lattice structure of the printed matrix. A prosthetic liner, for example, can be built entirely out of silicone. Typically, this would add considerable weight to the prosthetic, but 3D printing results in a lighter liner with the same or better properties in terms of mechanics and comfort.

One of the challenges with prosthetics and implantable devices is that every patient is different, observes Waitt: “The ability to customise geometry per patient is extremely powerful. 3D printing could theoretically create a way in which the device could be customised specifically to a particular patient.”

One example is how for millions of people who suffer from sleep apnoea, a badly fitting mask for their CPAP machine can not only be uncomfortable and cause irritation to the skin but can also mean they will not get the full air pressure they need. Currently, masks are mass produced but 3D printing will enable customisation of masks for better fit and comfort, facilitating an important industry trend to a more personalised model of healthcare.

Following this model closely, Elkem Silicones has now developed a production process called Liquid Deposition Modelling (LDM) which allows the use of a new series of customised silicone materials (the AMSil series) for use in 3D printing. This process allows high-performance parts with 100% silicones and with complex geometries and overhangs that are impossible to achieve using traditional dies or moulds. The AMSil Silbione 24 000 series is designed specifically for medical applications.

To find out more about silicone technologies and how they are supporting developments in four innovative medical device trends, download the whitepaper below.