"We've done a lot of work on polyvinylidene fluoride (PVDF) in the last few years." Dr Voit from the University of Texas at Dallas (UTD) mentioned. "If we produce PVDF under certain conditions, we can make it into a piezoelectric body, which means that if we stretch it, it will produce an electric current. Or by applying a voltage to the surface of the material, it can change its shape."
Other materials with similar characteristics, such as PVDF, have already moved into the ranks of modern technology, for example: pressure sensors in touchscreens and tilt sensors in electronic devices. But if their piezoelectric properties are significantly improved, their potential could extend far beyond first-generation applications.
In collaboration with Dr Priya from Virginia Polytechnic Institute and State University, Voit has made new progress towards this goal. They have led efforts to investigate "soft" polymer-based. Energy Harvesting Materials is part of the Energy Materials and Systems Harvesting Centre, a National Science Foundation project centred on the development of energy harvesting and motion control technologies.
Cary Baur, a PhD student in the Voit lab, has come up with a way to improve the piezoelectric properties of PVDF fibres by doping organic nanostructures (known as 'Buckyballs') and single-walled carbon nanotubes, where the 'Buckyballs' are tiny spheres made of carbon atoms. The "Buckyballs" are tiny spheres of carbon atoms. Scientists are exploiting this interesting inbred property in a variety of ways.
In Voit's experiments with this material, the carbon nanostructures can even increase the overall strength of the electric field. As a result, Voit mentions that this PVDF hybrid carbon is the best piezoelectric composite material available in the scientific literature.
Making these yarn-like structures into artificial muscles, i.e. materials that have tensile and compressive deformations if an electric current is passed through them or if the temperature is changed, would also require modification, and Voit's colleagues suggest one way of achieving this. much smaller scale. The structure can have nearly 50 % shrinkage when heated and can withstand a weight of about 16 lbs.
"The effect is similar to pulling a rubber band," says Voit. "When a rubber band is coiled, you get more strain when you stretch it."
Voit hopes to produce the same effect with his PVDF carbon fibre, a much better piezoelectric material than nylon, and one that can have the same effect on electrical currents. We have to coil it up and make sure it has the right piezoelectric properties when it's complex in shape," he says. Achieving this is really our secret weapon. Ultimately, it can be used to build synthetic muscles that can make prosthetics more realistic."
Voit mentioned that another potential use of the material he is working on that attracts commercial interest is the harvesting of energy. Boeing, which has provided some funding for his research, is interested in the use of energy generated by passengers on the plane. This would allow the airline to reduce some of its cables, which could significantly reduce the weight of the aircraft and save fuel, Voit said, because they could sit down, stand up and adjust their seats to power some of the equipment in the plane, such as the overhead lights in the room.
"We are now working on ways to process to a greater extent to create high-capacity energy harvesting devices and practical artificial muscles," Voit said.
