The topic of extracting electricity from "air" - from electromagnetic noise, vibrations, light, humidity and much more - worries both civilian researchers and their colleagues with shoulder straps. Your contribution to this topic from Pennsylvania State University. From the magnetic fields of nearby electrical wiring, they were able to extract electricity with a power of several milliwatts, which is enough, for example, to directly power a digital alarm clock.
Published in a magazine In the article, scientists talked about calculations and about the manufacture of special converters of electromagnetic fields into electric current. The extracting element is made in the form of a multilayer thin plate with a permanent magnet at the free end (the other end of the plate is securely fixed). The plate itself consists of a piezoelectric layer and a layer of material (Fe85B5Si10 Metglas).
A magnetostrictive material is interesting in that when the state of magnetization changes, its volume and linear dimensions change. The annoying buzz of coils in video cards is, as a rule, magnetostrictive changes in the cores. In an alternating magnetic field of ordinary electrical wiring with a frequency of 50 or 60 Hz, the Metglas plate begins to vibrate and deform the piezoelectric plate glued to it. In the network connected to the plates, current begins to flow.
However, a magnetostrictive material paired with a piezoelectric generates only up to 16% of the electricity generated by the element. The main production is given by the oscillation of a permanent magnet in an electromagnetic field. It is claimed that the peak voltage on the cell reaches 80 V in a field of 300 Β΅T. But the most valuable thing is that the developed element could produce enough energy to directly power digital clocks in the field with a power of less than 50 ΞΌT at a distance of 20 cm from the electrical wiring.
Researchers from the University of Pennsylvania conducted their research together with researchers from Virginia Tech and the US Army Combat Capabilities Development Command group.
Source: 3dnews.ru