Protocol developed for piezoelectric energy harvesters

Physicists from the University of Bath have developed a ‘best practice’ protocol for researchers developing piezoelectric materials, in response to findings that experimental reports lack consistency. The researchers discovered that nine out of 10 scientific papers miss experimental information that is crucial to ensure the reproducibility of the reported work. They addressed the need for a standardised piezoelectricity research protocol in the journal Nano Energy.

Dr Morteza Hassanpour Amiri at the Max Planck Institute for Polymer Research, Germany, said research into piezoelectricity has accelerated in recent years, because piezoelectric materials generate electricity when subjected to pressure or mechanical vibrations, or when they are tapped or distorted. With the addition of a circuit, this electricity can be stored and then used. Because of the potential of piezoelectrics, over the past 20 years a range of new materials and composites have been developed and tested for their energy harvesting potential, with many claiming high efficiencies. But the researchers, led by Professor Kamal Asadi from the Department of Physics, suggest these findings often do not include details of key experimental parameters. These details are essential to ensure reproducibility when other researchers set out to independently evaluate or further improve the featured materials.

“Reproducibility of experimental research findings may not be the key to the success of a research, but it is the key to ruling out unreliable findings from being accepted as fact. The enthusiasm to develop a champion material that shows impressive performance should be accompanied with enough supporting data,” Asadi said.

The Bath researchers assessed 80 randomly selected research papers published over the past 20 years on piezoelectric energy harvesting devices. For nearly 90% of these papers, essential experimental parameters — needed to evaluate materials and devices — were missing, thus rendering the experiments hard to reproduce.

“There are three important reasons why reproducibility is important: We are scientists and should strive to be as accurate as possible; we have limited resources, so by reporting all the necessary parameters that guarantee reproducibility, we are helping our peers to build up on our findings and advance the field; by being transparent, we also build trust with the public, and with science-funding organisations and policymakers, and provide a better guidance for future ‘big’ decisions that can affect us all,” Asadi said.

Asadi, a leading expert in piezoelectricity, said this lack of data is hampering progress in the field, as researchers can’t turn to the literature to identify materials with the best harvesting potential, and then further develop these promising materials. The new Bath protocol suggests a standardised data collection and reporting procedure. Professor Chris Bowen, from the Department of Mechanical Engineering at Bath, said the researchers have created guidelines that can help researchers in the field of piezoelectricity.

Asadi hopes that electronic devices powered by piezoelectricity will be on the market within the next decade. “That’s why it’s important to have a standardised protocol for reporting research data for a quantitative evaluation of energy harvesting materials and devices. Doing so enables scientists to make real progress building on each other’s experiments and working towards a common goal: making piezoelectricity a reality for anyone hoping to charge their devices more sustainably and without reliance on a traditional power source,” Asadi said.

Asadi added that the field of piezoelectricity energy harvesting has a lot of potential with great scientists working on it. “To make sure we advance as well and as quickly as possible, ensuring experiments are reproducible is going to be crucial, so I hope our suggested protocol is adopted by the community at large,” said Asadi.

Image caption: An artistic impression of electricity generation in a piezoelectric energy harvester made from piezoelectric nanofibres. Image credit: Katharina Maisenbacher, Max Planck Institute for Polymer Research.