A sensor based on silver nanowires is mounted onto a thumb joint to monitor the skin strain associated with thumb flexing. The sensor shows good wearability and large-strain sensing capability. Photograph courtesy of Shanshan Yao.
Researchers at North Carolina State University (NC State), Raleigh, have used silver nanowires to develop wearable, multifunctional sensors that could be used in biomedical, military, or athletic applications, including new prosthetics, robotic systems, and flexible touch panels. The sensors can measure strain, pressure, human touch, and bioelectronic signals such as electrocardiograms. They are stretchable up to 150 percent or more of their original length without losing functionality and can be mounted on a variety of curvilinear surfaces such as human skin. The work was recently published online in the journal Nanoscale.
“These sensors could be used to help develop prosthetics that respond to a user’s movement and provide feedback when in use,” said Yong Zhu, PhD, an associate professor of mechanical and aerospace engineering at NC State and senior author of the paper. “They could also be used to create robotics that can ‘feel’ their environment, or the sensors could be incorporated into clothing to track motion or monitor an individual’s physical health.”
The researchers built on Zhu’s earlier work to create highly conductive and elastic conductors made from silver nanowires. Specifically, the researchers sandwiched an insulating material between two of the stretchable conductors. The two layers then have the ability called capacitance-to store electric charges. Pushing, pulling, or touching the stretchable conductors changes the capacitance. The sensors work by measuring that change in capacitance.
The sensors have been used in several prototype applications. For example, the researchers employed these sensors to monitor thumb movement, which can be useful in controlling robotic or prosthetic devices, and they demonstrated an application to monitor knee movements while a test subject is running, walking, and jumping. The researchers also developed an array of sensors that can map pressure distribution, which is important for use in robotics and prosthetics applications. The sensors exhibit a 40 millisecond response time so strain and pressure can be monitored in real time.
Editor’s note: This story was adapted from materials provided by NC State.
