Professor Anne Ladegaard Skov

Strengthening Soft Robotics

torsdag 20 okt 22
af Morten Andersen


Anne Ladegaard Skov
DTU Kemiteknik
45 25 28 25

Soft Robotics

Unlike classic robots, soft robotics are made from soft and compliant materials, and thus has a smoother interaction with humans or can be used for implantable devices due to their compatibility with soft tissue. Soft robotics often rely on very thin materials, e.g., elastomers in thickness of less than 0.1 mm, and upscaling is not simple but sometimes requires independent innovations. The soft robotics era thus requires scientists involved in materials science, chemical engineering, production technologies, and other disciplines involved throughout the maturation from lab curiosity to commodity product.


Tailor-made polymers connected to a power supply can replicate the labour carried out by human muscles. The challenge is to increase the power to levels that may, for instance, improve the everyday life of people recovering from illness or accidents.

Imagine a person with reduced muscle strength putting on a shirt with built-in artificial muscles. This may become reality a few years from now, according to Professor Anne Ladegaard Skov, DTU Chemical and Biochemical Engineering.

“In our labs we have developed artificial muscles strong enough to lift a strawberry, or even a small apple. But to become commercially interesting they need to perform somewhat better. If, for instance, a person barely able to lift his or her own arms can suddenly lift two bags filled with groceries just think how much this would improve quality of life.”

How is the magic done? Anne Ladegaard Skov shows a di-electric silicone elastomer sample in size and shape much like the tiniest weight stick you might find in your fitness center. The polymer sample bends or stretches easily, and it feels very much like a relaxed human muscle. Due to the di-electric properties, the sample will bend or extend when voltage is applied. The amount of movement can be controlled through the voltage level and is fully reversible. This is much like the way electric signals from the brain triggers movement in our muscles.

Next generation pacemakers

Notably, the strength of the artificial muscles can be varied for a person under rehabilitation.

“Possibly you would not want the devices to do all the work for you. You might want your own muscles to take part for training purposes. And gradually you can change the ratio, so your own muscles lift more as they become stronger,” says Anne Ladegaard Skov, continuing:

“This is not just relevant for patients under rehabilitation. We all become weaker as we get old and will at some point be inclined to want a bit of help. Also, a market is likely to emerge for people who have normal muscle strength but may still want some relief for instance because they have a physically demanding job.”

On top of this comes entirely different applications:

“Take pacemakers as an example. These devices have become very advanced, when it comes to the main challenge of controlling the heart rhythm of the patient. However, many patients also have a secondary problem, which is lack of sheer muscle power of the heart. Imagine a dual function pacemaker that could both keep the right pace and deliver additional power through an artificial muscle.”

High safety requirements

What does Anne Ladegaard Skov see as critical for achieving the desired increase in strength of the artificial muscles?

“Well, since we are looking at devices that are in close contact with the body, or even implants, the safety requirements are obviously high. On the one hand, the materials need to be soft and biocompatible. On the other hand, we need materials, which are very stable, so they do not break due to the repeated contractions. Stability is also key to avoid short-circuits. I can say from personal experience that the typical voltage level we currently operate at, about 2 kilovolts, while not dangerous may still give you a very unpleasant experience.”

Therefore, the critical task ahead is to develop materials, which meet both the stability and biocompatibility requirements.

“This will take a highly cross-disciplinary research effort over the coming years.”

The research is anchored at the Danish Polymer Center (DPC) that is led by Anne Ladegaard Skov but will include groups outside the center and even outside DTU Chemical and Biochemical Engineering, not to mention industry partners.

“As a chemical engineer I find it very natural to engage in such broad collaborations. The polymer research is the core but many other disciplines such as electronics, physics, and mechanics are essential to get the necessary results,” says Anne Ladegaard Skov, adding that this is not just about development:

“We still have a range of basic research issues to tackle.”

Early approach from venture companies

As an example, Anne Ladegaard Skov mentions a polymer material developed in another project. The polymer in question performed well in the lab and seemed to have all the right properties but failed once being worn for several months by subjects during a real-life trial.

“This goes to show that many issues remain to be understood even for someone like me who has worked in the field for more than 20 years. Of course, experience will help you. Sometimes you just know that a given solution will work, but you cannot explain why. As a scientist, you want to be able to understand the mechanism behind your innovation. Not only because this is fulfilling but also because this is often the foundation for further breakthroughs.”

Given the huge market possibilities, no wonder the research of the professor and her colleagues receives wide attention. Both the Independent Research Council and the Novo Nordisk Foundation (NNF) have provided generous funding, allowing the work to continue for at least the next four years. In addition, no less than three venture companies have shown their interest.

“This was a bit surprising since the research is still basic. Normally you must come close to commercialization and put in a lot of effort in attracting venture capital. Here, we were approached before we even had a prototype ready,” Anne Ladegaard Skov notes, smilingly.

Model of commercialization remains to be found

Besides the obvious market potential in the soft robotics field, the personal track record of Anne Ladegaard Skov in entrepreneurship may have played a part in the interest of venture companies. She has been involved in three startup companies during her career. Will she have a fourth go to commercialize artificial muscles?

“That may well be, but it is too early to say. We still have four years left on the research project funded by NNF, and things can evolve in different directions. My feeling is that the potential is large, but whether commercialization should happen through collaborations with existing industry or through startups is not clear at this point.”

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