A Bismuth Rust-Based Wearable Generates Energy with a Curl of the Finger — and Makes Memories, Too
Bismuth rust, printed in seconds, forms the heart of a wearable which can be a nanogenerator, semiconductor, or memory component.
Researchers at Australia's RMIT University and the University of Melbourne have developed a nanomaterial wearable which can turn the curl of a finger into usable electricity — and even "make memories" in the form of stored micro-miniature images.
"The innovation was used in our experiments to write, erase and re-write images in nanoscale, so it could feasibly be developed to one day encode bank notes, original art or authentication services," senior lead researcher Ali Zavabeta, PhD, explains of the team's unusual rust-based wearable. "We tested natural motion behaviour with the device attached to a finger joint, with an average output peak of about 1 volt."
The wearable is built from a single nanomaterial housed in a flexible casing: the rust of bismuth, a low-temperature liquid metal known to be safe for use in wearable devices. As the user curls their finger, it generates electricity — but in addition to its capabilities as a nanogenerator, the wearable can also act as a semiconductor or as a memory component.
To prove the latter, the team demonstrated how the device could be used to write memory contents, read it back, and erase it — storing image data, including the RMIT logo, in a space twenty times smaller than the width of a human hair. Unlike rival designs, which rely on layers of different materials, it's also easy to make: "We fundamentally investigated this instant-printing technique for the first time using low-melting point liquid metals," lead author Xiangyang Guo explains of the production process, which takes just a few seconds.
"Bismuth oxide can be engineered to provide memory functionality, which is critical for many applications," Guo says of the material used in the device. "The material can act as a semiconductor, meaning it can be used for computation. It is a nanogenerator, meaning it is energy efficient with a green energy supply from environmental vibrations and mechanical movements."
The research team is now looking to expand its focus to other low-temperature liquid and solid metals and to find industry partners with which to collaborate on bringing the technology out of the lab and onto consumers' hands.
The team's work has been published in the journal Advanced Functional Materials under open-access terms.
Main article image courtesy of Seamus Daniel/RMIT University.