The wood magician and his amazing strip of paper

You can tell how well Empa’s invention was received, because the jury chose not to group it together with the technical gadgets – like the streaming headphones that you can wear underwater, or the on-the-go baby bottle warmer. Nor did they list it under the fun stuff like the indoor garden for beginners or the teddy bear that hugs back.

Certainly, Empa is no longer simply the “Building Materials Testing Institute”, as it was initially called when it was founded in 1880. In recent decades, the organisation has developed into a multi-branch research hub. It sees its core mission as carrying out solution-oriented research – for industry, but also for society.

Nyström himself is keen to stress the social dimension more than anything else. Although he is a physicist, he talks more like an environmental scientist. He will happily explain how the paper battery works (see box below), but soon starts emphasising the “bigger picture”, the potential ways in which the battery can be used, and how we can protect the environment. Nyström, 41, has three children. He wants his work, “above all, to contribute to a better future”, he says.

The paper battery is not a particularly powerful battery, nor does it have to be. There are now a wide range of small disposable electronic devices that run on very little power. These can be medical diagnostic devices, for example, or battery-powered smart parcel boxes that enable delivery tracking and even allow the temperature of sensitive items such as vaccines to be monitored during transit.

Nyström also sees potential in wearables, which are any technology designed to be worn for the purpose of monitoring things like heart rate or blood sugar. Furthermore, paper batteries would be more or less ideal for use in outdoor measuring devices. If for whatever reason the batteries were never retrieved, they would eventually decompose anyway.

Like the latest NASA space rocket, are we also about to see the stratospheric rise of the paper battery? Some companies have already expressed an interest, says Nyström, but whether anything comes of it remains to be seen, he adds. Yet what we do know is that he and his team will carry on researching. Their paper biodegradable supercapacitor is already at a very advanced stage of development. They also have an idea along the lines of a display system. “We see many exciting possibilities.”

All that remains is to ask the inventor which other inventions on the “Time” magazine list he finds intriguing. Nyström is true to form in his response. He doesn’t mention the “chameleon car” that can change colour, or the AI system that can create images and art. The inventions that Nyström describes as “particularly interesting” relate to sustainability – like the devices and methods that have been pioneered to help remove CO₂ from the atmosphere.

Water as the trigger

The Empa battery is made of a small strip of paper on which three different inks are printed. The ink on the front contains graphite flakes and acts as the positive end of the battery, while the ink on the back contains zinc powder and acts as the negative terminal. A third, special ink is printed on both sides of the paper, on top of the other two inks. Salt is dispersed throughout the strip of paper. Ingeniously, you activate the battery with water. One drop is enough. As soon as the paper is wet, the salts within the paper dissolve and the battery charge is released. But if the paper remains dry, the battery retains its charge. There is one disadvantage: the battery will only work for as long as it is wet. Tests show that it can keep a low-power alarm clock running for about one hour before it dries. Although pressure, heat or an external electromagnetic field could conceivably also be used as a battery trigger.