More efficient batteries, textile sensors, self-repairing concrete-at Empa, all kinds of materials are researched and enhanced. In an interview with the Werner Siemens Foundation, which supports several projects at Empa, Empa Director Tanja Zimmermann explains the significance of materials science, where the field is heading-and why wood is her favourite material.
Tanja Zimmermann, Empa is THE Swiss institution for materials science. How would the average person notice if the field no longer existed?
Roughly two-thirds of all’innovations stem from new materials: in other words, technological advances hinge on materials science. This also affects our ordinary, everyday lives, as developing products like new batteries or medical sensors would otherwise be impossible.
Are there typical kinds of materials engineered at Empa?
The materials and production technologies we develop and optimise fall into three main categories: construction, energy and health. The spectrum ranges from basic research to feasibility studies conducted in collaboration with industry partners. In the energy sector, for instance, novel and more efficient batteries and PV technologies are a key focus. However, researchers also create and develop entirely new classes of materials. One example would be so-called Mxenes, which are two-dimensional nanomaterials that could prove interesting as energy storage systems in electronics and sensor technologies.
And in the other two areas?
In terms of materials for medical applications, we’re developing textile sensors for long-term ECG monitoring that no longer contain metal electrodes: in addition to delivering reliable, long-term functioning, these sensors don’t irritate the skin. Another innovation is a plaster used as a sealant after abdominal surgery; the plaster contains integrated sensors that immediately send an alert should leakage occur. Meanwhile, in the construction industry, concepts for a circular economy and efficient use of resources are at the centre of interest. For instance, we’re working on new materials that match conventional building methods in strength, but use considerably less concrete and steel-and release much less CO2 during production. We’re even trying to develop carbon-negative materials.
What does that mean?
Even if human beings were to completely stop emitting carbon dioxide today, there would still be too much CO2 in the atmosphere. This, coupled with the fact that the concentration of atmospheric CO2 decreases at a very slow rate, means we need to find ways to remove it from the atmosphere, to clean it up, as it were. So the goal is to remove excess CO2 from the atmosphere, but rather than simply storing it underground, we want to use it as a raw material. Our new "Mining the Atmosphere" research initiative was launched to explore potential solutions, and more than half of all’Empa labs are participating in the endeavour. One approach we’re studying is whether carbon from CO2 can be used as a raw material to produce ceramic materials like silicon carbide. Another is whether building materials like concrete can be used for carbon storage.
That sounds a little like pie in the sky. Are there any Empa innovations that have already had a lasting effect on society?
Yes, there are many. At Empa, the goal has always been to effect change-for SMEs, for industry in general, for the health sector and for society. Our researchers have devised a method for manufacturing water-repellent sports gear that does away with problematic PFAS chemicals. Another example is a project in which extremely heat-resistant materials are used to build drones that can fly directly into a fire and take images for the fire brigade, without endangering human lives. And one of our labs has spent years developing carbon-fibre-reinforced polymers; part of this work included a collaboration some twenty years ago with the Alinghi sailing team, winners of the 2003 America’s Cup. These ultra-light yet incredibly robust materials are now being used in large-scale projects-namely to build bridges and other structures. The great advantage is that the new technology can replace large amounts of steel. As a result, the finished constructions are much lighter yet nonetheless demonstrate the same mechanical properties as those built using conventional materials. The list of fascinating innovations goes on and on.
How has materials research changed in recent decades?
We’ve witnessed a veritable transformation in the field. Digital technologies have brought about significant change-indeed, modern materials development is largely computer-aided and conducted using simulations, machine learning and digital twins. In addition, the huge advances made in technologies for analyses and material characterisation have also fundamentally altered how we work. What can now be imaged and studied at the atomic level is astonishing-for example, it was discovered that materials can display entirely different behaviours on the nanoscale compared to the microor macroscale. What’s more, materials research has become much more efficient. Today’s high-throughput systems are capable of characterising hundreds of samples in a very short time.
Empa as an organisation has also undergone massive change: what was once primarily a materials testing facility has evolved into an internationally renowned research institution. How relevant is materials testing today?
Traditional materials testing is no longer a major factor at Empa. If a private engineering company can perform a test, that’s the preferred course of action. However, we continue to play an active role in materials analysis and standardisation where highly specific expertise or customised devices are required.
Can you name any examples?
Well, the changing climate means that different types of trees will grow in our forests in the future. Pines and firs, which are traditionally used in the building industry, are in decline. In response, we’re using our testing hall to conduct stability experiments on supports made of deciduous timber for large structures. These findings are then incorporated into the standardisation process. We also investigated parts of the Morandi Bridge in Genoa, which collapsed in 2018. This work demanded the coordination of expertise in a variety of fields-including metals and corrosion as well as concrete and civil engineering. At Empa, we have specialists in all these areas.
Your background is in wood science. What is it about wood that fascinates you?
Wood is an incredibly versatile material that never ceases to amaze me. It’s the only sustainable, renewable resource we have in Switzerland. It’s light yet very robust. I find it fascinating how nature is able to produce such a functional, lightweight building material so efficiently. What’s more, wood can be easily modified or functionalised.
Can you explain that?
We modify wood in order to lend it antimicrobial, water-resistant or non-flammable properties.
How exactly?
One method involves introducing minerals to the wood to make it fireproof. Our first experiments here were with lime that accumulates on cell walls. We’re now exploring a similar approach with carbon, where the idea is to utilise wood as an even larger carbon sink while simultaneously strengthening its resistance to microbial decay. To create antimicrobial properties, we used the tools of chemistry to bond iodine to enzymatically activated wood.
Your main area of research is nano-cellulose. What is this material exactly?
Fibrillated cellulose, as we call it, refers to the cellulose fibrils that make up wood or other plant cell walls. With diameters in the nanometre range and lengths in the micrometre range, they have fantastic properties for technical applications. For instance, just adding a few of these fibrils to water results in the formation of a firm gel that’s either transparent or translucent. This gel can be used for many purposes-as a hydrogel, to name one possibility. Another potential application would be using it to fabricate sponges with such a high degree of porosity that they’re able to capture CO2 from air. We’ve also produced cellulose sponges that absorb oil but not water, a property that makes them interesting for cleaning up oil spills in bodies of water.
Are there other applications?
Yes, fibrillated cellulose can also function as a reinforcing material in adhesives. And when it’s compressed, it acts as an effective oxygen barrier. We’ve used it to create a spray-on coating for fruit and vegetables. Here, the fibrillated cellulose is sprayed on the produce in the form of a water suspension. When it dries, it forms a thin film on the surface that’s easy to wash off-in principle, you could also eat it. Using this method increases the shelf life of, say, cucumbers by up to two weeks.
You’ve even used fibrillated cellulose to create living materials.
That was fairly recently. It was part of the last large project on that I supervised, when I was already Director. We developed inks containing nanocellulose and diatoms-which are genera of algae-and succeeded in printing them with a 3D printer.
What can that be used for?
Diatoms are useful indicators of water quality. As a result, we’ve built sensors that react to impurities in the water, which could help monitor water quality in lakes and rivers. However, much work remains to be done before the concept can be translated into practical technology. But there are other ideas for using living materials: for instance, certain bacteria with the ability to transform certain nutrients into calcium carbonate could be introduced into cement. This approach could prove valuable for repairing hard-to-reach cracks in cement-you could call it a self-repairing cement.
Empa’s vision is to develop materials and technologies to bring about a sustainable future. How important are new materials for sustainable practices?
Of utmost importance. Sustainable practices-whether in the form of a circular economy, efficient use of resources or recycling-can only arise when the necessary technology is available. However, it’s also crucial that these practices are widely accepted in the general public and that the energy transition also delivers economic benefits. Our work takes place at the intersection between these competing priorities.
Why do some interesting research findings fail to find practical application?
There are various reasons. Through our work with more than three hundred and fifty industry partners in Switzerland, we’ve learned that the transfer to practice only works when it’s financially interesting-no matter how impressive the new materials and technologies are. It’s also critical to involve the public early on, something that has often been overlooked in the past. When engineers create something wonderful, there’s an assumption that people will accept it and use it. But the biggest reason for a research-to-practice failure is generally related to scaling up production: there are absolutely no guarantees that what works in the lab will work on an industrial level. That’s why it’s essential that Empa has a range of technology transfer platforms to test the viability of our materials for large-scale production.
Where do you see future areas of application for innovative materials?
There’s a great need for more research into materials surrounding the energy transition and climate change-this won’t change any time soon. Digitisation is another area. Here, it’s critical that Switzerland doesn’t join the game too late-and that we also seek a promising niche, as we simply don’t have the resources to acquire expertise in every aspect. The ageing population is also a major issue, and technologies for space exploration are both popular and cool. Another emerging area is one I would never have thought possible just a few years ago.
What would that be?
Security and defence. As a federal institution, Empa has a duty to investigate these topics when the Swiss authorities so require. This research will have to do with materials and with aspects such as securing a decentralised energy supply in the field or monitoring the vital signs of active-duty soldiers.
In what ways can foundations like WSS assist institutions like Empa in developing novel materials?
We’re profoundly grateful to foundations for their support. One excellent example is the WSS financing provided to Empa’s "CarboQuant" project-generous, long-term funding to outstanding researchers in a project that will take a long, indeed a very long time to yield results. It’s difficult to overstate how valuable it is that we can pursue this work, and also purchase high-calibre instruments, over a ten-year period.
If Empa could launch a bold and unconventional research project tomorrow, with no consideration given to funding or policy matters, what would you choose?
It would be something visionary along the lines of what I mentioned at the beginning of our conversation: the Mining the Atmosphere initiative, which aims to remove carbon from the air in order to reduce the amount of atmospheric CO2 to pre-industrial levels-while also finding meaningful uses for the harvested carbon. To achieve such an ambitious goal, we need to foster excellent relationships with numerous partners. Most importantly, however, we must first reach a point where we generate enough renewable energy. But if we succeed, it’s an endeavour with a massive impact!
