Miriam Haerst in front of the 3D printer she developed.

Together with her fellow founders, TUM alumna Miriam Haerst has developed a 3D printer that makes it possible to produce plastic implants and surgical aids with a precise fit (Image: Alexander Gerner/TUM).

Young talents
Entrepreneur Miriam Haerst
“To Be Truly Creative, You Have to Think outside the Box of Tried and True Methods”
21. Oct 2021  |  
Reading time Min.
Even as a schoolgirl, Miriam Haerst loved working with her hands and assisted her father in his hobby workshop. Her joy in experimenting and coming up with ideas has brought her a long way: from Diploma to Doctorate and finally to starting her own company. Her innovation is a 3D printer that can create individual bone implants from plastic.
In her school days, the main thing in Miriam Haerst’s cupboard were arts and crafts books. And her affinity for scientific topics already showed in high school. To this day, what fascinates her most are the logical processes in the world. Her Diploma thesis at TUM was on silicone elastomers in the field of Plastics Processing. Here she stood at the injection molding machine herself, produced test specimens and then examined the results mechanically. Working at the machine, fiddling with components, designing tools and testing specimens, physically looking at the results – in all of this, Miriam Haerst was fully in her element, and in the process had the best ideas. “It’s probably part of my personality that I can’t get hung up on simulation down to the last detail, but that I have to move into trial and error fairly quickly,” says the young Engineer.

And yet, for a long time, she found it hard to imagine studying Natural Sciences – and especially pursuing a Doctorate. She thought it would be too theoretical and not practical enough. Nevertheless, a year before her high school graduation, she attended the Herbstuni at TUM. This is a program specifically for schoolgirls, offering various courses in which, for example, they can program a robot or build bridges and learn about mechanics, trusses and force transmission. Being able to jump directly into hands-on experience and test the application of theoretical concepts appealed to Miriam Haerst and convinced her to enroll in Mechanical Engineering at TUM.


Today, she is the CEO of her own company and, together with her fellow founders – all four of whom are also TUM Alumni – has developed a 3D printer that makes it possible to produce plastic implants and surgical aids with a custom fit. The 3D printer, called Kumovis R1, has roughly the dimensions of a large refrigerator and can generate heat of up to 250 degrees Celsius. Together with hospitals and manufacturers of medical devices, the start-up is producing implants from high-performance polymers by using the 3D printer to apply the material layer by layer. The implants can be used to replace skull and facial bones, but also printed intervertebral disc replacements are conceivable.

Founder Miriam Haerst looks into the interior of Kumovis' 3-D printer, where a bone implant is currently being produced.

Founder Miriam Haerst looks into the interior of Kumovis' 3-D printer, where a bone implant is currently being produced (Photo: Alexander Gerner/TUM).

“It’s probably part of my personality that I can’t get hung up on simulation to the last detail, but I have to get into trial and error pretty quickly.”

Miriam Haerst

A genuine innovation on the market. “Compared to conventional methods, our process saves time and is relatively cheap,” Miriam Haerst says. Until now, individual implants, such as skull implants, have either had to be made by hand by the surgeon in the operating room or custom-milled in a medical technology company from a block of plastic. “The first method depends mainly on the skill of the surgeon, while the second method delivers high-quality results but often takes up to six weeks and is very expensive,” explains Miriam Haerst. With Kumovis’ technology, implants can be fitted within 48 hours. Printing could even take place directly on site at the hospital. Due to the lower costs, the likelihood that patients will receive custom-fit implants increases.


Talking about her time at TUM today, she emphasizes how much she enjoyed the free thinking at the Chair of Medical Engineering. “We were given the opportunity to think in all kinds of directions, to develop ideas and directly put them to the test,” she says. Even the foundations for the technology of her 3D printer were developed in a project seminar during her Doctorate.

Der 3-D-Drucker namens Kumovis R1 hat etwa die Dimensionen eines großen Kühlschranks und kann bis zu 250 Grad Celsius an Hitze erzeugen. Er produziert Implantate aus Hochleistungspolymeren, indem der 3-D-Drucker das Material Schicht für Schicht aufträgt (Bild: Alexander Gerner/TUM).

During its development, the young engineer and her co-founders continually faced new challenges. A good example was the innovation surrounding the temperature management of the 3D printer: “In order to create a product that meets the mechanical requirements of a bone substitute, the implant must be printed in high heat. Until now, people have tried to achieve this effect by applying heat from the outside, for example, by using infrared radiators.” The founding team of Kumovis initially also took this approach, but had not arrived at a suitable solution.

Finally, the five founders came up with the idea of trying a circulating air flow – similar to an oven with circulating heat. This was a decisive leap forward in development, because it meant that the air could also be filtered at the same time. “We didn’t stick with the old and instead consciously decided on a new approach,” Miriam Haerst reports. For this path, she was honored as one of the best innovators under 35 in 2019. “To be truly creative and develop solutions for existing problems, you have to think unconventionally and outside the box,” she is convinced. Experimenting with new things together as a team is her preferred method for doing so. “I always make sure to give us freedom as a team to spin ideas and to experiment. You never know what you’ll discover in the end.”

Porträtaufnahme von TUM Alumna Miriam Haerst.

Picture: Alexander Gerner/TUM.

Dr. Miriam Haerst

Diploma Mechanical Engineering 2011, Doctorate 2016

Still a student of Mechanical Engineering at TUM, Miriam Haerst gained her first experience in 3D printing while working for a manufacturer of hearing aids. During her Doctorate and work at the Chair of Medical Engineering at TUM, she focused on the processing of plastics for medical applications and the effects of a medical environment on plastics.

In a project seminar, she worked together with TUM Alumni Stefan Leonhardt, Stefan Fischer, Sebastian Pammer and Alexander Henhammer on a 3D printer for the high-performance polymer PEEK. After its first laboratory samples, it was clear that the group would keep at it for further development.

In 2017, Miriam Haerst co-founded the start-up Kumovis – with the help of TUM Start-up Consulting and an EXIST research transfer funding project from the German federal government. Kumovis currently has 25 employees, successfully completed its Series A financing round last year, and raised 3.6 million. This year, a subsidiary in the US was set up, Kumovis Inc.