Stretchable Hydrogel Electrodes Maintain Stable Signals During Movement

Wearable biosensors can struggle to maintain reliable skin contact during movement, sweating, or placement over hair, leading to noisy signals and discomfort. This limits continuous physiological monitoring in outpatient care, rehabilitation, and perioperative recovery. A soft, breathable, strongly adhesive interface could reduce setup time and improve data quality. To address this challenge, engineers have developed a tunable graphene hydrogel that forms conformal, reusable electrodes for stable biopotential recording.

Developed by Drexel University, in collaboration with Penn State University, the hydrogel integrates a tailored polymer network with conductive graphene to create breathable, stretchable biosensors. The team reports the material can be formed into customized shapes and sizes that maintain contact during bending and stretching. The work was published in Science Advances on July 15, 2026.

The hydrogel’s manufacturing process is governed by pH to delay gelation until dispensing, allowing smooth application from a syringe and rapid conformation to the target anatomy. Conductive flakes of laser-induced graphene and reduced graphene oxide assemble into a porous network that enhances electrical conductivity while permitting sweat to pass through the gel without buildup. Polydopamine, a polymer “bio glue” that mimics adhesive proteins in muscle tissue, reinforces skin adhesion under moisture and motion.

In preliminary testing, the hydrogel matched the softness of human tissue, stretched to 80 times its original length, and withstood dozens of peel-and-reapply cycles without measurable performance loss. It also adhered strongly to copper, steel, glass, and rubber, indicating versatility for biomedical interfaces. Electrocardiogram (ECG) electrodes on the wrist and chest maintained stable signals during bending, and electro-oculography (EOG) sensors captured consistent eye-blink activity through repeated movements.

To probe real-world performance, researchers created an array to track physiologic markers of anxiety by placing sensors on the eyelid, palm, and wrist. During alternating exposure to relaxing music and irritating sounds, and in a separate test exposing an arachnophobic volunteer to spider videos, the system continuously recorded rising sweat and blink responses consistent with a mounting fight-or-flight reaction. 

The team describes the findings as proof-of-concept and anticipates optimizing the gel for concurrent monitoring of heart rate, temperature, blinking, and muscle movement, with potential use in exercise monitoring for training and rehabilitation. The project was supported by the National Science Foundation and the National Institutes of Health.

“The ultimate goal of a biosensor is to be so reliable and comfortable that the wearer can go about their life without constantly noticing it’s there,” said Abu Musa Abdullah, Ph.D., a post-doctoral researcher of mechanical engineering and mechanics in Drexel’s Nick Howley College of Engineering and Computing.

“Taking this into consideration, we devised a formula for a hydrogel that can be printed in any shape or size and is adhesive enough to cling to skin even when it's sweaty or hairy and durable enough to be reused,” said Abdullah.

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