Simple but effective: double-sided adhesive tape and aluminum-coated plastic foil are enough to generate electricity, as an experiment has shown. Because when these everyday materials are combined, they form a triboelectric generator – they generate electricity when the foils glued to one another are shaken or repeatedly pressed. In the test, such a mini generator was sufficient to supply 400 LEDs or a laser diode with electricity.
The trend is towards mobile power generation: In the future, LEDs, sensors or mini-computers could also function without batteries by generating their power from piezoelectric or triboelectric nanogenerators. In these, friction, pressure or the shifting of material layers result in charge changes that can be tapped off as electricity. Embedded in the sole of a shoe, the floor or clothing, such nanogenerators can at least drive small devices.
“Since its invention in 2012, the triboelectric nanogenerator (TENG) has been one of the most promising candidates for small energy harvesters,” explain Moon-Hyung Jang of the University of Alabama in Huntsville and his colleagues. However, previous TENGs had a complicated structure and were expensive to manufacture. The researchers therefore looked for a way to achieve comparable performance with a nanogenerator using simple, readily available components.
The team developed a new concept for this that requires neither expensive components nor complicated production steps. Your triboelectric generator only needs double-sided tape and aluminum-coated PET plastic sheeting. Both are materials that are readily available at hardware stores or online. “Our power generation concept does not require any special manufacturing methods either,” Jang and his colleagues explain.
The components become a nanogenerator by simply combining them: The double-sided adhesive tape is stuck to an aluminum base, and the coated PET film is placed on top of it with the plastic side down. If these layers are now pressed together by pressure, there is a charge transfer at the border between the two layers: positive charges accumulate in the double-sided adhesive tape, negative charges in the PET layer of the film.
If the pressure decreases again and the adhesive connection even partially separates again, these charge differences lead to a discharge. “Contact with the penetrating air causes an abrupt relocation of the electrons in the PET layer,” explain Jang and his colleagues. This neutralizes the charge on this layer and the released electrons flow in the direction of the aluminum layers. “When the layers separate, a positive voltage can be measured,” say the researchers.
How well the generation of electricity works with this adhesive tape generator was tested by the scientists with different versions of this nanogenerator, including an adhesive tape with PET/aluminum foil on both sides. The necessary movement was provided by a simple spring construction, which brought the foil and adhesive tape on one side and the second foil on the other side into contact and separated again and again through pressure. In a second version, the foils were attached on one side, so that even a stronger shake caused the sticking and loosening.
The result: The simple nanogenerator generated an output of a good 21 milliwatts, the power density was up to 169.6 watts per square meter, as the scientists report. This is 47 percent more than previously measured with comparable triboelectric nanogenerators. In the test, an adhesive tape area measuring 38 by 25 millimeters was sufficient to supply 476 LEDs with electricity at the same time. The current was also sufficient for a laser diode.
Also positive: The simple adhesive tape construct proved to be amazingly durable: Even after 40,000 cycles of contact and separation, the performance of the nanogenerator decreased only slightly. “The power stays in the range of 19 to 24 milliwatts for up to 100,000 cycles,” reports the team. In her opinion, such simple and inexpensive nanogenerators are therefore well suited to powering sensors, LEDs or other small electronics, for example. (ACS Omega, 2022; doi:10.1021/acsomega.2c05457)
Quelle: American Chemical Society
This article was written by Nadja Podbregar
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