"The modified terpolymer thin film can lead to piezoelectric active sensors, such as force sensors. Combining these sensors with advanced fabrication technologies – inkjet or 3D printing – should make it easier to build a network of sensors."Xunqian Yin, INSA de Lyon
Energy harvesting offers a way for electronic devices to pull ambient energy from their surrounding environment and convert it into electrical energy for stored power. This coveted technology has the potential to serve as an alternative to the batteries that currently power our ubiquitous mobile and wireless electronic devices.
A group of smart materials known as ‘electrostrictive polymers’ have been studied for years by researchers at the INSA de Lyon in France for their potential mechanical energy harvesting abilities. Now, in a paper in Applied Physics Letters, the researchers report that introducing a plasticizer into these materials offers an efficient way to improve their energy harvesting performance.
The researchers’ work centers largely on the piezoelectric effect, which refers to the accumulation of electric charge in certain crystalline solids in response to an applied mechanical stress or strain. Normally, however, "the electrostrictive polymers are non-piezoelectric in nature," said Xunqian Yin, lead author and a researcher at the INSA de Lyon.
Instead, they produce the opposite effect, able to generate field-induced strain when exposed to an applied external electric field. "And this strain has a quadric equation described by the second degree relationship with the applied electric field," explained Yin.
Electrostrictive polymers can be given piezoelectric properties, though. "A pseudo-piezoelectric effect can be induced for electrostrictive polymers when they're exposed to a large applied bias DC electric field, " Yin explains. "As a result, the pseudo-piezoelectric effect was adopted for the mechanical energy harvesting via electrostrictive polymers."
In this latest work, the group studied the effects on mechanical energy harvesting of a variety of operating conditions, including a large applied bias DC electric field, as well as the amplitude and frequency of the applied external strain. They discovered that increasing the applied bias provides a way to improve the energy conversion efficiency.
In addition, when working with a plasticizer-modified ‘terpolymer’, they found it offered improved mechanical energy harvesting, especially when the same force level was applied. "The 'lossy' dielectric and mechanical nature of the modified terpolymer play an important role for energy harvesting based on electrostrictive polymers," Yin said.
Thanks to its large pseudo-piezoelectric coefficient, which is a result of the improved electromechanical coefficient that comes from introducing a plasticizer, "the modified terpolymer thin film can lead to piezoelectric active sensors, such as force sensors," said Yin. "Combining these sensors with advanced fabrication technologies – inkjet or 3D printing – should make it easier to build a network of sensors."
Next, the group plans 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," said Yin.
The group will also attempt "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."
This story is adapted from material from the INSA de Lyon, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.