Apr 24, 2020 
Stefan Leonhardt studied medical engineering at the Technical University of Munich. His research during his studies was focused on the influence of materials and manufacturing processes on the biocompatibility of polymer parts.
In 2015 he started his Ph.D. programme at the Institute of medical and polymer engineering at the Technical University of Munich, about the development of a biocompatible photopolymer for the production of individualized bioreactors used in tissue engineering processes.
Since October 2017 he is a managing partner of the Kumovis GmbH, a startup that develops innovative 3D-printing systems for the production of individualized implants out of PEEK. Stefan will be speaking at 3DHEALS2020.
(You can read Stefan’s previous interview with us here.)
Jenny: It’s more than a year since 3DHEALS interviewed you, can you share with us some of the major milestones with Kumovis since our last interview?
Stefan: The major milestone was the market launch of our first serial 3D printer, the Kumovis R1. We were able to win renowned medical technology companies as customers and partners and work together on applications that have a real impact in the medical sector.
I would also like to make special mention of our great team, which has grown strongly over the past year. It is really great to see how everyone is committed to Kumovis and to bring 3D-printing to the next level.
Jenny: How are you dealing with COVID19 personally and how is Kumovis responding to the crisis?
Stefan: Personally, I try to avoid as much contact as possible to other people. I really look forward to meeting again with friends and family but now everybody has to stay at home as much as possible.
At Kumovis most of the team stays at home and works in-home office. Only a small team is at the office to make sure the printers are running and that the customer projects are going on.
Jenny: Were there requests for Kumovis to produce 3D printing PPE locally? If so, please share the story with us.
Stefan: Yes, we were in contact with some hospitals here in Germany. We printed face-shields to support them and still have some open requests regarding reusable y-connectors for ventilators, which will be printed in the coming days.
Jenny: Kumovis’ products focus on point of care (POC) delivery of healthcare, locally produced 3D printed implants are probably the best example of that conceptually. Do you think we are really there when it comes to providing POC solutions to patients? If not, what are the remaining challenges?
Stefan: If we focus on implants printed at the point of care, we definitely need some more time. The major challenge is to set up an appropriate quality management system with qualified machines, materials, and validated processes. Also, we must focus on usability and implement all single steps of a full workflow including data processing and postprocessing. We are working on all these topics and hopefully can already present some first solutions in the near future 😊.
Jenny: What was your biggest victory in 2019? Please share that story with us.
Stefan: For us, it was always an internal goal to prove that we can achieve mechanical properties of 3D printed products made from high-performance polymers like PEEK that are comparable to traditional processing methods. This was an internal standard we set ourselves to hit before launching our series of printers. Achieving this goal was one of our biggest victories in 2019.
Jenny: What are you looking forward to or the biggest goals for Kumovis in 2020, especially in the context of the ongoing COVID19 crisis?
Stefan: One of the biggest goals is to go the next step in POC 3D-printing. Especially the ongoing COVID19 crisis shows us that it is important to provide medical solutions for patients even if supply chains are interrupted. POC 3D-printing really can make a difference here.
Jenny: In your previous interview, you mentioned that you were fascinated with the potential of 3DP to remove the production restriction of ideas. What were some of the examples you saw in the last 1-2 years that validated this belief?
Stefan: Yes, and I still am. I think it is great that more and more people are understanding the possibilities of 3D printing and are changing their way how to design products, for example, we saw developments of innovative instruments which included specific areas with features like a good radiopacity. Or all the new approaches to add bone-like structures at specific regions of an implant to improve ingrowth. The list goes on and on and is still rising as long as 3D-printing enters the medical market more and more.
Jenny: What were some of the major research breakthroughs relevant to your work at Kumovis in the past year?
Stefan: Besides high-performance polymers, we also put a lot of research resources into biodegradable polymers. We adjusted our temperature management system to find an optimal process that leads to minimized degradation during printing.
Another research topic was the development of new structures for optimized bone ingrowth. PEEK itself shows a hydrophobic behavior. In combination with coating technologies, we could create capillary effects within porous PEEK structures that are needed for nutrition transport and thus also favors bone ingrowth.
Jenny: Software, materials, or 3D printers. It has been an ongoing debate in the industry forever as to which is the most important player. Which do you think is the most important player in healthcare 3D printing?
Stefan: I truly believe that there is not ONE most important player. Of course, the hardware is very important as you can see that with different types of printers you can reach completely different values regarding quality and mechanical properties. But also, there must be medically approved materials on the market.
And of course, the software is in most cases the initial starting point. Without software solutions, we are not getting the models we want to print, and we also see a huge influence of for example slicing software on the final outcome of printed products. So, all in all, we have to focus on the whole process chain and that is exactly what we are also doing at Kumovis. In the end, we have to provide a full solution.
Jenny: There are a lot of talks around using machine learning or artificial intelligence to streamline the 3D printing workflow and production process (using in-print monitoring, etc.). How close are we to complete autonomous 3D printing with ML/AI?
Stefan: I think it still is a huge step to reach complete autonomous 3D printing. We have several projects regarding in-print monitoring, process documentation and how to learn from the generated data. In the future, we can benefit from ML/AI especially regarding the printing process and design optimizations.
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