Image showing how the novel 'flexo-electric' material changes shape when an electric voltage is applied. Image: University of Twente.
Image showing how the novel 'flexo-electric' material changes shape when an electric voltage is applied. Image: University of Twente.

Researchers at the University of Twente's MESA+ research institute in the Netherlands, together with researchers from several other institutions, have developed a ‘flexo-electric’ nanomaterial that changes shape when you apply electrical voltage, or that generates electricity if you change its shape.

In an article published in Nature Nanotechnology, the researchers also show that the thinner you make the material, the stronger this flexo-electric effect becomes. Guus Rijnders at MESA+, who was involved in the research, describes this as a completely new field of knowledge with some potentially interesting applications.

The ‘flexo-electric’ nanomaterial is basically a novel type of piezoelectric material, which are crystalline materials that can convert electrical power into pressure and vice versa. Piezoelectric materials have several disadvantages, however, in that they contain lead – which has environmental and health risks – and the piezoelectric effect decreases as the material gets thinner.

Ever since the 1960s, physicists have been arguing that the flexo-electric effect could exist, allowing non-piezoelectric materials to be given piezoelectric properties. At that time, however, manufacturing methods were inadequate for the production of such materials. Now, researchers from the University of Twente, the Catalan Institute of Nanoscience and Nanotechnology and Cornell University have succeeded in developing a flexo-electric nanomaterial just 70nm thick made from strontium titanate. It turns out that even though the flexo-electric effect is very weak, the thinner you make the material, the stronger the effect becomes.

According to Rijnders, it will eventually be possible to create flexo-electric materials with a thickness of just a few atomic layers, which would have all kinds of interesting applications. “You could make sensors that can detect a single molecule, for example,” he explains. “A molecule would land on a vibrating sensor, making it just fractionally heavier, slowing the vibration just slightly. The reduction in frequency could then easily be measured using the flexo-electric effect.” In addition, flexo-electric materials could find use in devices that require a regular supply of power but are located in hard-to-reach places, such as pacemakers or cochlear implants inside the human body.

This story is adapted from material from University of Twente, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.