Swiss researchers at ETH Zurich and EMPA have created a new material with piezoelectric properties that is capable of generating electricity when walked on. The idea, of course, is not new – to use the energy of human steps for passive generation of electricity has been tried many times and not without success. Of interest is the material itself and the method of its production – this is ordinary wood treated with a special fungus.
To maximize the use of the piezoelectric potential, the material must be pliable, but elastic, so that it not only deforms easily, but also quickly returns to its original state without damage. Wood is prevented from making lignin fibers, a kind of natural polymer, which gives this material its strength. Swiss scientists have developed two new “delignification” methods that safely remove lignin, turning wood into a soft, porous sponge.
In the first case, a chemical method is used, soaking in a solution of hydrogen peroxide and acetic acid. A cube of the material obtained by this method with a face size of 1.5 cm withstood more than 600 compression cycles and produced a voltage of 0.63 V. An array of 30 cubes under the weight of an adult was able to power a small LCD display.
In the second case, a biological effect was applied by removing lignin from wood using the fungus Ganoderma applanatum, which decomposes it safely. It turned out to be cheaper, cleaner and more profitable, the voltage on the cube increased to 0.87 V. There is still too little for lighting or connecting household appliances, but it already looks quite like a source of energy for smart home sensors promising.