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Society has learnt to efficiently harvest energy from the major energy sources such as sun, wind or rivers. But what about the small motions – walking, opening a door, writing or even breathing? These everyday small motions can be used to harvest energy and power some small-scale electronics.
Imagine you go for a hiking trip into the wild, where there is no access to electricity, and you do not have a power bank with you to charge up your smart watch.
Now imagine a different scenario of a large industrial machine. This machine must spin all the time and the rotational speed always needs to be measured. Often these speed sensors are battery powered, and therefore it can be difficult to change the batteries without interrupting the machine spinning or interrupting the flow of measurements.
Many of us take electricity as a granted resource, always at hand, although there are many people around the world who have no access to electricity at all. For them, to light up a study desk for instance, candles or petrol-based lamps are necessary, these options can be expensive and with limited time of usage.
There are more than a million people around the world with pacemakers, which are necessary for them for their heart to beat properly. These pacemakers are battery powered, and these batteries must be changed every 5 to 10 years. Even though in most cases this happens in older age, some people still end up changing the battery more than once during their life. Nowadays the risks of the battery replacement manipulation are lo, but it is still a risk, especially for very old people.
Although it is not obvious, but there is one common solution to all of the presented problems. Team NANO is working on this solution.
Team NANO is a team of interdisciplinary students, founded in 2019, aimed at creating a novel kinetic-electrical energy conversion technology. The technology wished to be developed is affordable, convenient and efficient, for the use of community-wide or even citywide energy production. The generator is small and can be incorporated onto pre-existing urban infrastructures such as roads, bike paths, offices and even the TU/e campus, In wireless technology (keyboards, remote controls), self-lightning notebooks or in medical applications in the human body.
The generator consists of two sheets of a combination of polymers, designed specifically according to materials tribo-polarity. As can be seen in the "Working principle" picture, energy generation requires a cyclic process of pushing the plates together and releasing them. Once the plates come into contact triboelectric effect takes place, due to which electrons are transferred from one plate to the other. Once the plates are not in contact again, we are left with two plates with opposite charges, which makes a potential difference. Therefore, once the plates are connected with a wire the charges can flow from one plate to the other through the wire and therefore an electric current is created.
The nanogenerators provide high flexibility in terms of applications. In theory they could be used in any of the situations mentioned in the problem statement above. In order to charge a smart watch, the plates could be put into shoes, therefore electric power can be produced by walking or running. At the same time, it also has high potential in the field of self-powered sensors. If we come back to the previously described problem. Nanogenerators could use the motion of spinning to harvest energy for the sensor. Of course, it would cause extra friction for the machine, but there would be no batteries involved as a result. Alternatively, a sheet of nanogenerator plates could be put under a sheet of paper, which would then power LEDs under the paper allowing to write during night. The most ambitious idea, however, is to try to extend the battery life of a pacemaker by making use of the motion of breathing. Although the power that is generated is not large, even extending the battery life by one month on the 10-year period can make a difference.
Last year the first prototype was made, which was proof of concept, because it was possible to light up an LED with the plates. The team is now working on measuring precisely the maximum and average output power. The project is still only at its start and does not produce enough energy to power any of the previously mentioned devices. However, the team is very passionate and working hard to make this dream come true.
Fan, F. R., Luo, J., Tang, W., Li, C., Zhang, C., Tian, Z., & Wang, Z. L. (2014). Highly transparent and flexible triboelectric nanogenerators: performance improvements and fundamental mechanisms. J. Mater. Chem. A, 2(33), 13219–13225. https://doi.org/10.1039/c4ta02747g