A new technology that can harness energy from natural motions and activities has been developed at the Massachusetts Institute of Technology (MIT) in the US.
Researchers at MIT have designed the new system based on electrochemical principles, which can offer a small but virtually unlimited power supply from walking and other motions.
It has been based on the slight bending of a sandwich of metal and polymer sheets, MIT said.
Earlier inventions had based the devices on the triboelectric effect or piezoelectrics, which made them work with high-frequency sources of motion including those created by machinery vibrations.
Those systems, however, had limits for typical human-scale motions such as walking or exercising.
MIT Nuclear Science and Engineering and professor of materials science and engineering Battelle Energy Alliance professor Ju Li said: "When you put in an impulse to such traditional materials, they respond very well, in microseconds. But this doesn’t match the timescale of most human activities.
"Also, these devices have high electrical impedance and bending rigidity and can be quite expensive."
Details about the new flexible invention have been published in the journal Nature Communications.
The electrochemical technology used in the device is similar to that of lithium ion batteries and can be produced at minimal costs in large scale.
It involves the use of two thin sheets of lithium alloys as electrodes, which are separated by a layer of porous polymer soaked with liquid electrolyte, which in turn, can efficiently transport lithium ions between the metal plates.
Power produced by the system comes in the form of alternating current (AC), unlike that in batteries and solar cells.
It results in conversion of mechanical energy to electrical, and thus "it is not limited by the second law of thermodynamics," Li said.
The new technology can be used to power wearable devices with daily motions. It can also be used as actuator with biomedical applications, or for embedded stress sensors in settings including roads, bridges, keyboards, or other structures, MIT said.
Image: Power produced by the system comes in the form of alternating current. Photo: courtesy of the researchers/MIT