A team of researchers have demonstrated the viability of the direct piezoelectric effect in a thin film Bismuth Ferrite Material for the first time. The work, published in Nanoscale entitles “Direct and Converse Piezoelectric Responses at the Nanoscale from Epitaxial BiFeO3 Thin Films Grown by Polymer Assisted Deposition” which has gained the cover letter of such journal.
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In this particular research, the BFO was scanned in a novel methodology named “Direct Piezoelectric Force Microscopy” DPFM, a new AFM mode invented in 2017
(https://www.nature.com/articles/s41467-017-01361-2 ). The material in this mode is stressed by the AFM tip with nanometric size. The tip applies a force in the range of hundreds of microNewton and measures the generated charge that is created by the material. For the case of BFO material, the piezoelectric characteristics were collected when the tip crosses antiparallel domain configurations, see the following video for a 3D representation of the tip crossing such configuration: https://youtu.be/ir3W2Vk8hCs
Piezoelectric materials hold great promise as sensors and as energy harvesters but are normally much less effective at high temperatures, limiting their use in environments such as engines or space exploration. However, a new piezoelectric device developed by a team of researchers from Penn State and QorTek remains highly effective at elevated temperatures.
Clive Randall, director of Penn State’s Materials Research Institute (MRI), developed the material and device in partnership with researchers from QorTek, a State College, Pennsylvania-based company specializing in smart material devices and high-density power electronics.
“NASA’s need was how to power electronics in remote locations where batteries are difficult to access for changing,” Randall said. “They also wanted self-powering sensors that monitor systems such as engine stabilities and have these devices work during rocket launches and other high-temperature situations where current piezoelectrics fail due to the heat.”
A skin-like polymeric material is using carbon nanotubes (CNTs) to bring a sense of touch to robotic and prosthetic devices. Developed by researchers at Stanford University and Xerox Palo Alto Research Center, the flexible, polymeric skin or ‘digital tactile system’ (DiTact) incorporates CNT pressure sensors and flexible organic printed circuits to mimic human response [Tee et al., Science 350 (2015) 313].
‘‘We wanted to make a sensor skin that communicates in the same way as the body,’’ explains research student Alex Chortos, one of the lead authors of the work. ‘‘The goal is to make skin for prosthetics that can feel touch in a natural way and communicate that information to the person wearing the prosthetic device.’’
In the body, receptors in the skin relay sensing information directly to the brain in a series of voltage pulses rather like Morse code. Artificial devices employ tactile sensing to improve the control of neuroprosthetics and relieve phantom limb pain. But, to date, prosthetic skin devices have had to use a computer or microprocessor to turn the output from sensors into a signal compatible with neurons.
The new approach, by contrast, combines these operations in a single system of piezoresistive pressure sensors embedded in a flexible circuit layer. The sensors are made from a CNT composite dispersed in a flexible polyurethane plastic and molded into pyramidal structures. The pyramidal shape is crucial because it allows the pressure range of the sensor to be tuned to that of skin.
Government gives go ahead for world’s largest windfarm
The second stage of the world’s biggest offshore wind farm has been given the go-ahead by the UK Government. The Hornsea Project Two scheme could see 300 turbines being built across 55 miles off the East Yorkshire coast to deliver up to 1.8MW of electricity to 1.8 million UK homes. The turbines will be connected to the grid at North Killingholme in North Lincolnshire.
Approval for the project was delayed for several months after concerns were raised about its potential impact on porpoises. Hornsea Project Two is the second stage of Dong Energy’s planned development of the Hornsea Zone in the North Sea. The windfarm is expected to create up to 1,960 construction jobs and 580 operational and maintenance jobs.
Business and Energy Secretary, Greg Clark, said his decision to give consent would lead to ‘jobs and economic growth right across the country.’ The UK aims to use wind power to provide 10% of the entire country’s energy needs by 2020.
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I wonder what would happen if the blades on a windmill had solar panels and piezoelectric membranes to absorb more energy.
Well, windmills with solar panels technically are a thing, though I believe there’s still some work to be done before they’re put into production. Check out this US patent on the topic, which was actually published 10 years ago in 2006, as well as this company that focuses on solar wind turbines.
Rochelle salt, aka potassium sodium tartrate tetrahydrate, NaKC4H4O6·4H2O, was the first material found to produce an electric discharge when compressed. This phenomenon, called piezoelectricity, is used in many lighters and grill starters. The salt is relatively easy to grow, says crystallization hobbyist Dmitry Shintyakov, so large, clear prisms like the one shown here are readily accessible. Shintyakov shares his methods online, so you can join the fun.
Transparency discovered in crystals with ultrahigh piezoelectricity
Use of an AC rather than a DC electric field can improve the piezoelectric response of a crystal. Now, an international team of researchers say that cycles of AC fields also make the internal crystal domains in some materials bigger and the crystal transparent.
“There have been reports that the use of AC fields could significantly improve the piezoelectric responses — for example by 20% to 40% — over DC fields and the improvements have always been attributed to the smaller internal ferroelectric domain sizes that resulted from the cycles of AC fields,” said Long-Qing Chen, Hamer Professor of Materials Science and Engineering, professor of engineering science and mechanics, and professor of mathematics at Penn State. “About three years ago, Dr. Fei Li, then a research associate at the Materials Research Institute at Penn State, largely confirmed the improvement of piezoelectric performances from application of AC fields. However, it was not clear at all how the internal ferroelectric domains evolved during AC cycles.
According to researchers, the work “presents a paradigm to achieve an unprecedented combination of properties and functionalities through ferroelectric domain engineering, and the new transparent ferroelectric crystals reported here are expected to open up a wide range of hybrid device applications, such as medical imaging, self-energy-harvesting touch screens and invisible robotic devices.”
