Researchers from North Carolina State University have developed a new, wearable sensor that uses silver nanowires to monitor electrophysiological signals, such as electrocardiography (EKG) or electromyography (EMG). The new sensor is as accurate as the “wet electrode” sensors used in hospitals, but can be used for long-term monitoring and when a patient is moving.
Long-term monitoring of electrophysiological signals tracks patient health or assist in medical research, and may also be used in the development of new powered prosthetics that respond to a patient’s muscular signals.
Electrophysiological sensors used in hospitals, such as EKGs, feature wet electrodes that rely on an electrolytic gel between the sensor and the patient’s skin, to improve the sensor’s ability to pick up the body’s electrical signals. The technology, however, poses problems for long-term monitoring. The gel dries up, irritating the patient’s skin and making the sensor less accurate.
The new nanowire sensor is comparable to the wet sensors in terms of signal quality, but is a “dry” electrode and does not use a gel layer.
“The silver nanowire sensors conform to a patient’s skin, creating close contact,” says Dr. Yong Zhu, an associate professor of mechanical and aerospace engineering at NC State and senior author of a paper describing the work. “And because the nanowires are so flexible, the sensor maintains that close contact even when the patient moves. The nanowires are also highly conductive, which is key to the high signal quality.”