Almost everyone has a scar somewhere on their body. Scar tissue forms whenever an injury affects not just the uppermost skin layers but also the underlying connective tissue. To close the injury, the body first forms collagen fibres that pull the edges of the wound together again. However, the resulting scar tissue is tougher and less elastic than healthy skin. It can take years for the original skin structure to be restored.

In the case of severe skin injuries such as burns, the scar may also undergo pathological alteration. Overproduction of collagen makes it thick and bulging, which can cause pain and limit mobility. That is why doctors observe the healing of scar tissue for at least a year. Bettina Müller, a postdoc at the Institute for Mechanical Systems at ETH Zurich, has now developed a measuring device called “Nimble” to assist in these examinations.

Medicine and technology combined

When she was still in secondary school, Müller already knew that her profession would have something to do with medicine. But at the age of 14, this native of Feldkirch, Austria decided to specialise in electrical engineering, so she ended up taking subjects like computer science and high-frequency engineering instead of biology. Nevertheless, she later found a way to combine her technical background with her interest in medicine: by studying medical technology at the Technical University of Munich.

For her doctoral thesis, she then deliberately sought out a project with an immediate practical application. The scientist says:

The development of a skin examination device as a subproject of the interdisciplinary Skintegrity.CH call_made alliance has more than fulfilled these expectations.

The measurement method was already established in the group led by Edoardo Mazza, Professor at the Department of Mechanical and Process Engineering, when Müller began her work. Her task as a biomechanical engineer was to make a device that is flexible and easy to use in medical skin checks. For one thing, it requires a small measuring head that can reach every corner of the body.

Measuring skin elasticity with a vacuum

Today – five years after starting her doctoral thesis – the 32-year-old is closer to application than ever before. In early September, she received an ETH Pioneer Fellowship to pursue the project. The goal is to bring “Nimble” to market as a medical device within two years. “From a medical perspective, the device’s added value is undisputed,” Müller says, adding that this became clear in discussions with doctors during the clinical trials.

Is the scar hard and immobile or soft and elastic? Today, dermatologists examine this using a technique called palpation. This involves the doctor grasping a fold of skin and assessing how much it gives when they pull on it. “If you have enough experience, palpation works well,” Müller says. But the technique has some disadvantages: the results depend on the person performing the examination, and it is difficult to register tiny changes over time.

This is where “Nimble” comes in. Whereas dermatologists previously had to feel for any changes in skin structure, “Nimble” now makes them measurable for the first time. The measurement principle is simple to understand: A round suction head pulls at the skin with a vacuum, lifting it by a few millimetres. The stiffer the skin, the more negative pressure this requires. In a clinical study involving burn patients at the Children’s Hospital Zurich, the measuring device reliably distinguished between healthy skin and scar tissue on different parts of the body.

Motivation from practical experience in the hospital

In a second study, Müller showed that the measuring device is also suitable for diagnosing the rare autoimmune disease scleroderma. In affected individuals, the skin on the fingers and face hardens as a result of excessive collagen production – similar to a scar. The progression of this disease is already measured by changes in the skin; “Nimble” can document these more accurately over time.

However, getting the measuring device out of the workshop and into the clinic was definitely one of the greatest challenges. “We always talk about a prototype. But in fact, what you’re dealing with is a device made up of many individual parts,” Müller explains. For example, the software installation in the hospital didn’t work right away. Seemingly mundane things like attaching the measuring head didn’t come as naturally to the medical staff as it did to Müller.

Müller particularly likes working on clinical trials. “Seeing your research being applied in the hospital is incredibly motivating,” she says, adding that input from doctors played a decisive role in developing “Nimble”.

From researcher to entrepreneur

Conduct a market analysis, calculate company costs, write a business plan: recently, Müller’s daily routine has centred around entrepreneurial work rather than research. Although Müller often feels “like a beginner”, the consulting services and the opportunity for exchange with other Pioneer Fellows make her feel up to these new tasks.

“I’m aware that there’s no guarantee the start-up will succeed,” Müller says, “but it’s precisely because the measurements work so well that I’m highly motivated to bring this device to market.” Her friends and family are also very aware of her enthusiasm for her project: “Sometimes I talk about it so much that it’s probably a bit annoying,” she says with a laugh.

Regardless of this, the ETH researcher receives great support from her boyfriend and her family. “They’re really understanding of the fact that I don’t have much time for them right now,” Müller says. She likes to spend her free days outdoors, hiking or cycling. And when she doesn’t manage to get away, she can at least enjoy a splendid view of the mountains from her office desk.