California researchers are developing a microscale actuator – which may have practical applications in mechanical muscles, the delivery of medications and microfluidics and radiation-detection robots.
Working at the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California, Berkeley, the scientists say that they came up with an “elegant and powerful” microscale actuator.
Its small size is impressive, being “smaller than the width of a human hair.” It can also “flex like a tiny beckoning finger.” It uses an oxide material which can expand or contract based on the temperature.
"We believe our microactuator is more efficient and powerful than any current microscale actuation technology, including human muscle cells," Junqiao Wu, a scientist who worked on the project, said. "What's more, it uses this very interesting material—vanadium dioxide—and tells us more about the fundamental materials science of phase transitions."
The vanadium-dioxide actuators provide three times the force than human muscle. As part of the study, it was known that vanadium dioxide goes from an insulator to a metal after getting sufficiently heated reaching a temperature above 67 degrees Celsius.
The material shrinks upon sufficient heating. Also, when a strip of vanadium dioxide is heated, it contracts and the strip “bends like a finger.”
"The displacement of our microactuator is huge," Wu explained in the lab statement, "tens of microns for an actuator length on the same order of magnitude—much bigger than you can get with a piezoelectric device—and simultaneously with very large force. I am very optimistic that this technology will become competitive to piezoelectric technology, and may even replace it."
Currently, piezoelectric actuators are the standard for mechanical actuation on micro scales. But they present many challenges in practical applications. They are difficult to grow, they require large voltages and often use toxic materials such as lead.
"But our device is very simple, the material is non-toxic, and the displacement is much bigger at a much lower driving voltage," Wu said. "You can see it move with an optical microscope. And it works equally well in water, making it suitable for biological and microfluidic applications."
To watch a video on the research please click here.
Lawrence Berkeley National Laboratory is involved in diverse fields of research. Recently, CalCEF and the Berkeley Lab announced that they are partnering in coming up with CalCharge, a consortium of California's battery technology companies, and academic and government resources.
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Edited by Brooke Neuman