Wires for wearable electronic devices get a flexible makeover

Wearable electronic devices, such as those used in human motion tracing and physiological signal measurement, must be highly flexible and stretchable. It is essential that the electronic wires of these devices achieve electrode connection of functional components and ensure efficient transmission of circuit signals. Zhu et al. developed a cost-effective, highly porous liquid metal composite that proves suitable for constructing various flexible and stretchable electronic circuits and sensor electrodes.

“The non-stretchability of traditional wires can lead to additional constraints on soft structures,” said author Bingliang Ye. “The rigid wire and flexible sensor electrode connection methods can also make interface mismatch inevitable.”

While liquid metal is considered an ideal material for stretchable wires, its fluidity and high surface tension present challenges in adhering to flexible substrates. To tackle this difficulty, the team used a porous structure, generated by neodymium iron boron particles, to achieve liquid metal droplet locking. They also added nickel particles to regulate the conductivity, magnetic, and mechanical properties of the material, which allowed the construction of porous structures with fewer magnetic particles.

The resulting liquid metal showed stress/strain insensitivity, good wettability, conductivity, and diverse patterning methods. Electronic wires made from the composite exhibited anti-leakage and anti-damage. The composite is suitable for constructing various flexible and stretchable electronic circuits and electrodes for sensors.

“This work will promote the development of electronic software robots by deploying flexible sensors, transistors, and other electronic devices on software structures, and connecting them through stretchable electronic wires, making software robots closer to the biological model of receptor cells to neurons,” said Ye.

Source: “Liquid-metal/NdFeB/Ni composites for high wettability, patternable, stretchable electronic wire,” by Zhifang Zhu, Ran Zhao, Bingliang Ye, and Huan Wang, AIP Advances (2023). The article can be accessed at https://doi.org/10.1063/5.0158221 .