In 2025, students from TUM won a gold medal with their concept for a tattoo that monitors health-related parameters. In 2026, a team from Munich is competing again.

From dragons to hearts to butterflies, the drawings in Kalina Elkin's hand could easily be from the local tattoo studio. But there's more to these designs than meets the eye; they're for very special tattoos: "Our aim is to use the colored surface areas as a biosensor for the sex hormone progesterone," says Elkin.

The idea: When the body's progesterone concentration exceeds a certain level, the tattoo darkens in color. This makes it possible to read the body's  hormone status at a glance, without the need to draw blood and perform laboratory tests. "A tattoo like this could help track the female cycle, for example in pregnancy planning," Elkin explains. "But the principle could also be applied to other biomarkers." She is a Bachelor's student in Life Sciences Biology at TUM and is active in the iGEM Munich student initiative. 

The Munich team participated in the October 2025 iGEM finals in Paris with its "InkSight" concept. The students reached the top 10 in the overall ranking and won a gold medal as well as several special prizes. iGEM stands for the "International Genetically Engineered Machine (iGEM)" competition, a student competition in the field of synthetic biology. The goal of the contest is to introduce students to scientific work practices as early as possible.

What began in 2004 as an event with just five university teams in Boston has grown to become an internationally renowned meeting that showcases research questions related to all aspects of synthetic biology. In 2025, more than 400 teams from high schools and universities around the world participated in the three-day finals held at the Paris Convention Centre. The competition itself was complemented by a program featuring expert lectures; start-ups and established companies also had the opportunity to present themselves. 

Teams in München and Straubing

The eight-member team wasn't Munich's first time in the iGEM competition: Interested students from TUM and Ludwig-Maximilians-Universität Munich (LMU) come together in November every year. They spend two semesters working together on their research projects, from the initial idea through planning and execution of the experiments, all the way to final documentation. The competition's requirements include organizing financial subsidies as well as interaction with the public. For instance, the 2025 team organized a three-day bioengineering crash course for advanced biology students at the Werner-Heisenberg-Gymnasium in Garching.

The TUM Campus Straubing for Biotechnology and Sustainability fielded its first iGEM team in 2024. The Straubing students plan to enter the synthetic biology competition in 2026 again.

Designing and assembling molecular components

Synthetic biology, also referred to as Engineering Biology, applies engineering science principles in designing molecular building blocks, usually proteins or DNA, in such a way that they perform particular functions. These components can be assembled to form larger biological systems. The findings generated in the process are then transferred to the development of new medications and materials.

"The iGEM competition provides students with valuable insights into the application areas of synthetic biology," says Gil Westmeyer, Professor of Neurobiological Engineering at TUM, who advised the 2025 iGEM Munich team. "It's exciting to see how dedicated they are to turning their ideas into reality in the lab. 'BioSysteM', the new Cluster of Excellence for synthetic biology in Munich‚ will generate exciting possibilities for many more students in the future."

The iGEM Munich student research projects have already earned several awards. For example, in 2016 the students brought the main prize home to Munich with a 3D printing process for live tissue. The higher-level objective was to artificially generate human organs for transplantation medicine.

"Living biosensors" for a variety of biomarkers

The  idea of the biosensor tattoo, the 2025 iGEM team's entry in the competition, is based on human cells which are embedded in a hydrogel. In their experiments the students used genetic technology methods to add nanocages to these cells. These nanostructures produce the skin pigment melanin. In the experimental setup, a receptor on the cell’s surface detects when progesterone levels exceed a certain threshold. This triggers a signal cascade, causing the nanocages to distribute evenly throughout the cells – making them appear darker. “Such a biosensor tattoo would let you see at a glance whether a critical range has been reached,” says Elkin. “That’s the idea.”

The vision behind the project would be to create a tattoo with surfaces of various colors that can simultaneously measure changes in several biomarkers. "The 'living biosensor' concept together with our software could in the future be applied to other biomarkers which serve as indicators for certain biomarkers," says Friedrich Irmer, a Bachelor's student in Bioinformatics at TUM and LMU. As an example, he cites excessive levels of troponin, which may indicate heart disease.

“We’re at an early experimental stage,” Irmer says. For the iGEM finals, though, that was more than enough. In addition to the gold medal, the students won special prizes for “Best Diagnostics Project,” “Best Software,” and “Best Wiki.” “But it would be a long road to actually put the biosensor tattoo into use,” he adds.

All the hours spent in the lab and at the computer have paid off, says Aeneas Tews, also a Bioinformatics Bachelor's student. "We were able to put a lot of the things we've heard in the lecture hall into practice in our project. And we're also learning a lot from one another, from students who are at home in entirely different disciplines. It's a fantastic experience." That’s why he will be taking part again in 2026, when the new iGEM student team from Munich competes in the iGEM finals in Paris.

Friedrich Irmer will then support the students in an advisory capacity this year, as will Kalina Elkin. She is especially pleased about the objective of the iGEM competition: Finding solutions for a healthier and more sustainable world. “You get to develop something entirely new which someday might help people,” she says. “And that’s a very addictive feeling!” 

Further information and links

• At the iGEM finals, the team reached the top 10 in the overall ranking and won a gold medal for excellence in synthetic biology. The students also received special awards for “Best Diagnostics Project,” “Best Software,” and “Best Wiki.”
• The iGEM Munich team is supported by the two Munich universities TUM und LMU. The support at TUM came from the Anneliese Pfannenberg-Stiftung and Freunde der TUM e.V. (TUM Association of Alumni and Friends), among others.
• The Excellence Cluster Biosystem Design Munich (BioSysteM) will receive new supportfunding starting 2026. BioSysteM's objective is to create self-organizing molecular and cellular systems with programmable, life-like properties. The researchers develop biomolecular machines, intelligent materials and pattern-based therapeutics. As a basis for new medical applications, they are also researching the control of cell differentiation and organ formation. The participating institutions are TUM, Ludwig-Maximilians-Universität Munich (LMU), the Max Planck Institute of Biochemistry and Helmholtz Munich.

Technical University of Munich
Corporate Communications Center

Undine Ziller
undine.ziller@tum.de
presse@tum.de
Teamwebsite

Contact about this article

Prof. Gil Westmeyer
Technical University of Munich
Chair of Neurobiological Engineering
gil.westmeyer@tum.de 

Original article: https://www.tum.de/en/news-and-events/all-news/press-releases/details/a-tattoo-as-biosensor