Wearable device makes memories and powers up with the flex of a finger

The innovation features a single nanomaterial incorporated into a stretchable casing fitted to a person’s finger. The nanomaterial enabled the device to generate power with the user bending their finger.

The super-thin material also allows the device to perform memory tasks, as outlined below.

Multifunctional devices normally require several materials in layers, which involves the time-consuming challenge of stacking nanomaterials with high precision.

The team, led by RMIT University and the University of Melbourne in collaboration with other Australian and international institutions, made the proof-of-concept device with the rust of a low-temperature liquid metal called bismuth, which is safe and well suited for wearable applications.

Senior lead researcher Dr Ali Zavabeti said the invention could be developed to create medical wearables that monitor vital signs — incorporating the researchers’ recent work with a similar material that enabled gas sensing — and memorise personalised data.

“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,” said Zavabeti, an engineer from RMIT and the University of Melbourne.

The team’s research is published in Advanced Functional Materials.

The team says the study revealed their invention exhibits “exceptional responsiveness to movements associated with human activities, such as stretching, making it a promising candidate for wearable technologies.”

“We tested natural motion behaviour with the device attached to a finger joint, with an average output peak of about 1 volt,” Zavabeti said.

The device was able to perform the memory functions of “read,” “write” and “erase,” which included using the RMIT logo and a square-shaped insignia as demonstrations of these capabilities. The device, which was not worn by a user during these memory experiments, wrote and stored the logo and symbol in a space that could fit 20 times within the width of a human hair.