While current approaches to energy harvesting may yield a trickle of power suited only for running ultra-low power devices between sleep states, engineers in France have found a way to enhance the energy harvesting performance of a type of smart material called electrostrictive polymers.
Researchers at the National Institute of Applied Sciences of Lyon (INSA de Lyon) have been researching the potential uses of electrostrictive polymers for mechanical energy harvesting. In their latest breakthrough, they found that they could introduce a plasticiser into the smart material, in order to improve their performance.
Electrostrictive polymers can produce field-induced strain when exposed to an applied external electric field. This strain has a quadric relationship with the applied electric field.
When a large applied bias DC electric field is used, the material, despite being non-piezoelectric in nature, induces a pseudo-piezoelectric effect, accumulating electric charge.
The researchers looked at how by varying the amplitude and frequency, they could affect the strain, and discovered that increasing the applied bias would improve the energy conversion efficiency.
As a result, they modified the material with a plasticiser, to form a "terpolymer". The introduction of the plasticiser improved the electromechanical coefficient, resulting in a large pseudo-piezoelectric coefficient.
This new smart material not only offers improved mechanical energy harvesting performance, but can also be used to create highly sensitive force sensors. The technology can be combined with advanced fabrication technologies like inkjet or 3D printing to quickly and easily build a network of sensors.
The researchers now want to explore in further detail the role that the electrostrictive polymer's lossy nature plays during the mechanical-to-electrical energy conversion process, with a view to establishing guidelines for the development of mechanical energy harvesters based on electrostrictive polymers.
The group will also attempt to find a more efficient plasticizer to modify terpolymer, hoping to find a modification that can reduce energy losses, and improve electromechanical performance when a under a low applied electric field is in place. This would allow the energy harvesting device to operate with low electric fields, making it safer and more convenient.