Researchers with the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory and the University of California, Berkeley, have developed an elegant and powerful new microscale actuator that can flex like a tiny beckoning finger. Based on an oxide material that expands and contracts dramatically in response to a small temperature variation, the actuators are smaller than the width of a human hair and are promising for microfluidics, drug delivery, and artificial muscles.
“We believe our microactuator is more efficient and powerful than any current microscale actuation technology, including human muscle cells,” says Berkeley Lab and UC Berkeley scientist Junqiao Wu. “What’s more, it uses this very interesting material—vanadium dioxide—and tells us more about the fundamental materials science of phase transitions.”
Vanadium dioxide is a textbook example of a strongly correlated material, meaning the behavior of each electron is inextricably tied to its neighboring electrons. The resulting exotic electronic behaviors have made vanadium dioxide an object of scientific scrutiny for decades, much of it focused on an unusual pair of phase transitions.
The researchers envision using the microactuators as tiny pumps for drug delivery or as mechanical muscles in micro-scale robots. In those applications, the actuator’s exceptionally high work density—the power it can deliver per unit volume—offers a great advantage. Ounce for ounce, the vanadium-dioxide actuators deliver a force three orders of magnitude greater than human muscle.