Jan 27 2016
A research group at France's National Institute of Applied Sciences of Lyon (INSA de Lyon) have discovered a technique to improve the mechanical energy harvesting performance potential of smart materials called, "electrostrictive polymers."
Energy harvesting shows potential to be a suitable method for electronic devices to extract ambient energy from their surrounding environment, and convert it to electrical energy for stored power. This desired technology could be used as an alternative power supply for batteries in mobile and wireless electronic devices.
"Electrostrictive polymers" - a cluster of smart materials - have been a focus of research for years at the INSA de Lyon due to their potential mechanical energy harvesting capabilities. In AIP Publishing's 'Applied Physics Letters', the research group explain that by introducing a plasticizer into the materials, mechanical energy harvesting performance can be improved.
This is a notable breakthrough, as improving the performance of mechanical energy harvesting using electrostrictive polymers has been a challenge during development.
Field-induced strain can be produced when electrostrictive polymers are introduced to an applied external electric field.
And this strain has a quadric -- equation described by the second degree -- relationship with the applied electric field.
Xunqian Yin, Researcher, INSA de Lyon
The research team's work focuses largely on the piezoelectric effect - the accumulation of electric charge in some crystalline solids, with no symmetric center when subjected to mechanical strain or stress.
[In this case] The electrostrictive polymers are non-piezoelectric in nature, but a pseudo-piezoelectric effect can be induced for electrostrictive polymers when they're exposed to a large applied bias DC electric field. As a result, the pseudo-piezoelectric effect was adopted for the mechanical energy harvesting via electrostrictive polymers.
Xunqian Yin, Researcher, INSA de Lyon
The team examined the influences on mechanical energy harvesting in several operating conditions; such as large applied bias DC electric field, and the frequency and amplitude of externally applied strain. They found that increasing the applied bias provided an improvement in the energy conversion efficiency.
A plasticizer-modified "terpolymer" offered a better mechanical energy harvesting performance, particularly when imposed to the same force level, and it can be tapped to produce sensitive force, sensors.
The 'lossy' dielectric and mechanical nature of the modified terpolymer play an important role for energy harvesting based on electrostrictive polymers.
Xunqian Yin, Researcher, INSA de Lyon
Due to its large pseudo-piezoelectric coefficient, resulting from enhanced electromechanical coefficient produced by a plasticizer, "the modified terpolymer thin film can lead to piezoelectric active sensors, such as force sensors," pointed out Yin. "Combining these sensors with advanced fabrication technologies -- inkjet or 3D printing -- should make it easier to build a network of sensors."
[The group plan to explore] the role that the electrostrictive polymer's lossy nature plays during the mechanical-to-electrical energy conversion process to establish guidelines for the development of mechanical energy harvesters based on electrostrictive polymers.
Xunqian Yin, Researcher, INSA de Lyon
The research group will also try "to find a more efficient plasticizer to modify terpolymer, which can contribute to lower energy losses and also improve its electromechanical performances under a low applied electric field," added Yin. "The lower the electric field, the safer and more convenient it is for applications."
Source: https://www.aip.org/