From smartwatches to fitness trackers, wearable devices are becoming part of everyday life. Hence, their sensors must remain reliable as they bend and stretch with the body. Many conductive hydrogels-soft, water-rich materials well suited for skin-contact sensors—face a "toughnes-conductivity" trade-off: they may stretch easily but lose electrical signal stability, or conduct well but lack the mechanical durability needed for repeated use.
In a study published in the KeAi journal Wearable Electronics , researchers from China developed hydrogels with a robust branched architecture (RBA) by introducing a highly branched polymer into a PEDOT:PSS-based hydrogel system. This created a denser web of molecular connections, allowing the materials to stay intact under strain while preserving pathways for electrical signals.
"Wearable sensors must move with the body while keeping signals stable," says corresponding author Baoyang Lu, a professor at Jiangxi Science & Technology Normal University. "By building a denser branched network, we made the hydrogels more resistant to deformation while preserving pathways for electrical signals."
The RBA hydrogels can stretch to more than three times their original length while remaining mechanically stable. The hydrogels were sandwiched between protective layers to reduce water loss and maintain stable electrical responses during repeated use. When used as strain sensors, the resulting devices detected subtle facial movements such as smiling, as well as larger motions of the fingers, elbows and knees. They also distinguished walking, jogging and running in real time.
Beyond motion tracking, the sensors were also used in a non-verbal communication system. When attached to a finger, they converted movements into Morse-code-like electrical patterns. With a lightweight machine-learning model, the system recognized commands such as "YES," "NO," "HELP" and "SOS" with 96.26% accuracy.
"This approach could support future wearable systems for health monitoring, rehabilitation and human–machine interaction, especially when speech or movement is limited," Lu adds. "Our study offers a simple route to tougher, more reliable hydrogel sensors."
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Contact the author: Baoyang Lu, Jiangxi Provincial Key Laboratory of Flexible Electronics, Jiangxi Science & Technology Normal University, Nanchang, Jiangxi, China, luby@jxstnu.edu.cn
The publisher KeAi was established by Elsevier and China Science Publishing & Media Ltd to unfold quality research globally. In 2013, our focus shifted to open access publishing. We now proudly publish more than 200 world-class, open access, English language journals, spanning all scientific disciplines. Many of these are titles we publish in partnership with prestigious societies and academic institutions, such as the National Natural Science Foundation of China (NSFC).
Wearable Electronics
Experimental study
People
A Superbranched Multi-Armed Crosslinking Strategy for Robust Conducting Polymer hydrogel toward Wearable Sensing and Encrypted Communication
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.