3D knitting for an artificial heart: Charlotte won the Saxion Talent Award for her master's thesis

Studying abroad

Charlotte, who hails from Germany, had long wished to study abroad. During her undergraduate studies in Textile Technology and Textile Management at Reutlingen University, near Stuttgart, she planned to spend a semester at another university across the border. The corona pandemic threw a spanner in the works, after which Charlotte, who had by now earned her degree, reconsidered her options for studying abroad. She found one in the form of the master's degree in Innovative Textile Development at Saxion. So, Charlotte moved to Enschede two years ago to start her master's degree programme. “This master's degree matched my desire to explore the world of textiles in more depth and at the same time learn even more about innovative and sustainable applications of textiles,” says Charlotte.

Holland Hybrid Heart

The first year of her master's degree was spent attending classes and taking part in team work and projects. After that, Charlotte was allowed to start her research. “I was particularly drawn to an assignment of the Saxion Sustainable and Functional Textiles Research Group, as part of the extensive, long-term research initiative with the Holland Hybrid Heart consortium. The development of an artificial heart has sparked interest in further research into textile applications. I was immediately interested. Above all, I was impressed by having the opportunity to contribute to such an important project, which helps people with heart failure.”

Soft robotics and 3D knitting

Charlotte's research focused on combining soft robotics and 3D knitting techniques to create a seamless, one-piece object which forms part of an artificial heart. During her bachelor's degree she wanted to explore the world of knitting techniques in more depth. While doing her master's degree, she got the opportunity to conduct research into a highly innovative application that could ultimately contribute to the development of a maximum functioning artificial heart. “Although a prototype already existed, the research group was keen to explore the use of new materials that might offer a more sustainable alternative. Textile applications could be a good option. The discussion also covered 3D knitting, a process that allows you to produce an entire object from the machine in a single step, using just one yarn. A major advantage is that you have no connections between the various parts. That's usually where the weak points lie.”

Artificial heart

Let's zoom out for a moment. An artificial heart. What is the current state of play? Charlotte also had to delve into that subject in preparation for her research. “If people have severe heart failure, a heart transplant is usually the best option to positively influence the quality and length of their life. But there is a shortage of donors, so there is an increasing number of applications being developed to partially or completely support the heart. Both in the heart and externally. Holland Hybrid Heart research aims to improve these applications, including the use of soft materials that are more compatible with the body."

Flexible materials

There are plenty of challenges, for example in the areas of technology, stability and the risk of infections or rejection, Charlotte explains. “With an external support device, there is always a connection line to the body. This may lead to an increased risk of bleeding and infections. That is why researchers are now investigating a bio-compatible hybrid heart. Hybrid means that it is an artificial heart powered by soft robotics, flexible, pliable materials with properties similar to those of a muscle, for example. The aim is to create a heartbeat and blood circulation in a more natural way. Inside the body, without connection to an external support device. It is not available yet, only as a prototype. And that's where I stepped in with my research into the use of seamless knitted 3D textiles.”

Seamless knitting

After extensive literature research and discussions with researchers from the medical and robotics world, Charlotte initially made several designs that she discussed with specialists. She chose polyester because of its application in other medical textiles. While other medically approved textile types were more suitable, their prohibitive cost made them impractical for use at this proof-of-concept stage. “It was really a proof of concept: is it even possible to seamlessly shape a heart, or a part of it, using 3D knitting of textiles? My prototype could not be implanted but you can see it as a basic preliminary study. Textiles, for example, are more sustainable than silicone. They are stronger and therefore last longer. I also examined the pneumatic properties of the textile, which involves using air to create movement. Because the fabric isn't airtight, I had to use an extra balloon with a cover. This ensures that parts are set in motion. Ideally, the fabric should be airtight, making the balloon unnecessary. But that is complex and requires further research in the future.”

Combining disciplines

The heart is an extremely complex organ. “Of course, I already knew this,” says Charlotte, “but I became even more aware of it through my studies of literature and conversations with physicians and specialists in the field of soft robotics. Our heart pumps in beats, but some artificial hearts work with a circulatory system. This does not involve a pumping function; rather, it is the constant rotation of the blood. Before I could start working on my prototype, I needed to develop a solid understanding of all these variations. I also needed to understand how soft robotics specialists view the relationship between their field and mine, i.e. technical textiles. After creating and evaluating several of my own design concepts, I transformed part of an existing design from the Holland Hybrid Heart Project into a seamless 3D knitted textile with a new structure. I used a flatbed knitting machine for this. That was also a challenge because I had to learn how to programme the machine.”

Pushing boundaries

How were Charlotte's prototype and accompanying master's thesis received? “People found the construction of textiles remarkably interesting because there was not much knowledge in that specific field. It has inspired the researchers involved to consider new possibilities. To push the boundaries of their use of materials.” Looking back, Charlotte realises that pushing boundaries certainly applied to her own situation. She had to combine her own area of expertise with knowledge of medicine and robotics, while also learning about pneumatic drive techniques. Programming the knitting machine was also new to her. “It was fantastic to push my own boundaries in such an enthusiastic interdisciplinary team. Everyone had a different background but ultimately, we had the same goal. My research will be continued by another student who will further develop my proof of concept. It was great that I could be a link in an extensive line of research.”

Saving lives

And finally, what was it like to receive her Saxion Talent Award on stage last week? “I was incredibly surprised. I really hadn’t expected to win first prize. In fact, I was already very honoured by the nomination and invitation to attend the opening of the academic year. In the end, it only got better. I hope my research can inspire others to think about textile applications. Textiles are so much more than the clothes we wear. There is a vast number of possible applications, including medical. I think there's a lot more to come. More than we currently realise. I personally thought it was great that I was given the opportunity to show what is possible. These types of applications could ultimately save lives. This master's thesis was a huge step outside my comfort zone. I never imagined that I would win a prize with it. Aside from the higher research goal, I found it personally rewarding. Totally unexpected. But sometimes you just have to try it.”

Fotography winners: Eric Brinkhorst
Other: Charlotte Wohlmeiner
Translation: Diane Huibers (Saxion Translation Services)