Silver nanowire sensors hold promise for prosthetics, robotics

Jan 16, 2014 by Matt Shipman
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. Credit: Shanshan Yao, North Carolina State University

(Phys.org) —North Carolina State University researchers 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.

"The technology is based on either physical deformation or "fringing" electric field changes. The latter is very similar to the mechanism used in smartphone touch screens, but the we've developed are stretchable and can be mounted on a variety of curvilinear surfaces such as human skin," says Shanshan Yao, a Ph.D. student at NC State and lead author of a paper on the work.

"These sensors could be used to help develop prosthetics that respond to a user's movement and provide feedback when in use," says Dr. Yong Zhu, 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.

"Creating these sensors is simple and low cost," Yao says. "And we've already demonstrated the sensors 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. The researchers also demonstrated an application to monitor knee movements while a test subject is running, walking and jumping.

"The deformation involved in these movements is large, and would break a lot of other sensor devices," Zhu says. "But our sensors can be stretched to 150 percent or more of their original length without losing functionality, so they can handle it."

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 quick response time – 40 milliseconds – so strain and pressure can be monitored in real time.

Explore further: Understanding interface properties of graphene paves way for new applications

More information: The paper, "Wearable Multifunctional Sensors Using Printed Stretchable Conductors Made Of Silver Nanowires," is published online in the journal Nanoscale: DOI: 10.1039/C3NR05496A

Related Stories

Wearable technology can monitor rehabilitation

Dec 13, 2012

Wearable technology is not only for sports and fashion enthusiasts it can also be used to monitor and aid clinical rehabilitation according to new research published in BioMed Central's open access journal ...

Recommended for you

A new way to make microstructured surfaces

35 minutes ago

A team of researchers has created a new way of manufacturing microstructured surfaces that have novel three-dimensional textures. These surfaces, made by self-assembly of carbon nanotubes, could exhibit a ...

Tough foam from tiny sheets

20 hours ago

Tough, ultralight foam of atom-thick sheets can be made to any size and shape through a chemical process invented at Rice University.

Graphene surfaces on photonic racetracks

Jul 28, 2014

In an article published in Optics Express, scientists from The University of Manchester describe how graphene can be wrapped around a silicon wire, or waveguide, and modify the transmission of light through it.

Simulating the invisible

Jul 28, 2014

Panagiotis Grammatikopoulos in the OIST Nanoparticles by Design Unit simulates the interactions of particles that are too small to see, and too complicated to visualize. In order to study the particles' behavior, he uses ...

User comments : 0