Moldable Sensor Could Support Neck Muscle Monitoring and Rehabilitation

Voice disorders and upper airway diseases may require repeated assessment of the small neck muscles involved in breathing, swallowing, and speech. Monitoring these muscles can be difficult because of the neck’s curved surface and the small size of the target muscles, limiting the practicality of conventional electromyography during rehabilitation. To address these challenges, researchers have developed a putty-like electrode designed to support more comfortable muscle monitoring and biofeedback.

Researchers at McGill University (Montreal, Canada) developed the soft electrode as a moldable sensor that conforms closely to the skin. The device is made from a silicone-based putty that conducts electricity through tiny embedded silver wires. Because it is dry, it does not require conductive gel and can maintain close contact with the skin with less air between the electrode and recording surface. This design is intended to reduce interference when recording signals from small neck muscles.

The electrode also has a strain-responsive electrical property that helps preserve conductivity as the material moves. When the putty stretches, the embedded silver wires rearrange in a way that maintains electrical flow. This feature may be particularly useful on curved or moving body surfaces, where conventional wet electrodes can be less practical. While current electromyography sensors perform well on larger muscle groups in the arms and legs, recording from smaller neck muscles remains more challenging.

In a proof-of-concept human study, the researchers shaped the putty into neck electrodes and tested them in three volunteers. Participants completed vocal tasks designed to induce fatigue, allowing the team to evaluate recordings under conditions involving low muscle activity signals. The sensor matched a standard clinical electrode in terms of noise and signal stability while recording from small neck muscles. The findings were published in Science Advances.

The researchers said the sensor could eventually help monitor breathing, swallowing, and speech during rehabilitation after stroke or in neurodegenerative diseases such as Parkinson’s. They also noted that larger studies and regulatory approval will be needed before the technology can be used clinically. The work points to a potential route toward wearable biofeedback tools that could support patients practicing muscle-strengthening exercises outside the clinic.

“As a speech pathologist, I have muscle-strengthening exercises I can give to patients, but we can only see them 30 minutes a week, or even monthly. If we have a muscle sensor that can be used as biofeedback for the patient while they practice at home, they can know if they are using the muscle correctly,” said Nicole Li-Jessen, Professor in the School of Communication Sciences and Disorders and an Associate Investigator in the Translational Research in Respiratory Diseases Program at the Research Institute of the McGill University Health Centre.

“The human study is a proof of concept, not a clinical trial. It shows that the electrode records clean signals from small neck muscles, where standard electrodes struggle,” added Li-Jessen.

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