Researchers develop energy-efficient reminiscence sensor for moist, salty environments

August 1, 2025 by Marni Ellery

UC Berkeley professor Junqiao Wu has spent over a decade working with vanadium dioxide, a compound recognized for its skill to shift between insulating and metallic states. By harnessing this uncommon property, he and his lab have developed modern applied sciences starting from “smart” roofing supplies to ultra-precise thermography strategies.

Now, they’ve found a brand new utility for this versatile materials. In a study published today (August 1) in Nature Materials, Wu and his workforce demonstrated how vanadium dioxide can be used to assist digital sensors extra effectively interface with moist, salty methods — a persistent drawback for scientists and engineers.

Using this materials, the researchers created a brand new in-memory sensor, or memsensor, that may each detect and bear in mind its chemical surroundings, enabling it to adapt to difficult aqueous circumstances. And, not like typical designs, it might probably do all of this with out exterior energy enter or complicated circuitry.

“This breakthrough could pave the way for simpler, more energy-efficient sensors and adaptive robots capable of operating in complex environments,” mentioned Wu, the research’s principal investigator and the Chancellor’s Professor within the Department of Materials Science and Engineering. “It may also open exciting possibilities for next-generation computing systems that integrate memory and sensing in liquid settings, much like how biological neurons function in the brain’s wet, ionic environment.”

Based on what they knew about vanadium dioxide, the researchers puzzled if the fabric may doubtlessly be used to assist digital sensors effectively function underneath such circumstances.

“While it was already known that vanadium dioxide can switch phases and ‘remember’ changes when doped with certain ions, we wanted to explore whether this could automatically happen in water with mobile ions, similar to how nerve cells in living organisms sense and store information with ion motion,” mentioned Ruihan Guo, lead creator of the research and a graduate pupil researcher in Wu’s lab.

To create their memsensor, the researchers connected a skinny layer of vanadium dioxide to a small piece of indium, an especially smooth, silvery steel. When the gadget is positioned in salt water, indium releases ions the place the answer touches the vanadium dioxide. With the built-in electrical fields on the solid-liquid interface, the ions are drawn to vanadium dioxide’s floor, inflicting a part of the fabric to show metallic — a resistance change that persists over time.

This shift in conductivity successfully “records” the historical past of salt publicity, and the speed of conductivity change correlates with the salt focus. More importantly, the memsensor can sense and retailer this info with out the necessity for any exterior voltage.

The nematode C. elegans makes use of specialised neurons to recollect salt publicity and information its motion towards or away from environments whereas foraging for meals. Mimicking this adaptive habits, the brand new memsensor navigates a small robotic boat by various salt gradients. (Image courtesy of the researchers)

“Using vanadium dioxide’s ability to switch between insulating and metallic states, we were able to create a fast, energy-efficient, in-memory sensor capable of operating in salt solutions and retaining information about the salt concentration even when the sensor is taken out of the solutions,” mentioned Guo.

While engineering their memsensor, the researchers took inspiration from the tiny nematode C. elegans. “This worm uses specialized neurons to remember salt exposure and guide its movement toward or away from certain environments when searching for food,” mentioned Guo. “Mimicking this behavior, we used our sensor to direct a small robotic boat to navigate salt gradients — avoiding undesirable zones and seeking favorable ones — based on its prior salt exposure history.”

Wu defined that their memsensing expertise could sometime be helpful in designing low-power aquatic robotics. Such robots may discover underwater or contaminated environments whereas adapting their actions like dwelling organisms.

“In a broader sense, the underlying principles point toward the possibility of brain-inspired computing in wet environments — just like our own brain, which operates in a salty, aqueous medium,” he mentioned. “In such systems, devices could sense, store and process chemical information spontaneously, all within a single, integrated platform.”

This work was supported by the U.S. Department of Energy Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division. For extra particulars and an entire record of authors, view the study.

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