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FAMU-FSU College of Engineering doctoral candidate Joshua DeGraff developed an advanced class of scalable motion sensors using silver ink electrodes and sheets of pure carbon nanotube buckypaper. Credit FSU Photography Services

A new breed of sensitive and flexible motion sensors could pave the way to a new wave of wearable devices.

A team of researchers from the Florida A&M University-Florida State University College of Engineering have created a new class of motion sensors that improves on existing sensors that are either too crude or too inflexible to reliably monitor complex structures like the human body in wearable technology.

“Current technology is not designed for that,” Richard Liang, director of the High-Performance Materials Institute and professor at the FAMU-FSU College of Engineering, said in a statement. “For sensor technology, you need it to be flexible, you need it to be affordable and you need it to be scalable.”

“This new technology is versatile and the sensors are affordable to print,” he added. “It's a big innovation that presents many possibilities down the road.”

The researchers developed the sensors using buckypaper—razor thin and flexible sheets of pure and durable carbon nanotubes. The sensor combines a strip of seven micron-thin buckypaper with silver ink electrodes printed from a common, commercially available ink-jet printer.

The sensor is not as insensitive as common, flexible metallic sensors, but also not as rigid or cumbersome as popular, more sensitive semi-conductor sensors.

“We measure sensors by gauge factor, which indicates how much resistance value changes as a material is strained or bent,” doctoral candidate Joshua DeGraff, the lead author of the study, said in a statement. “Our gauge factor has been up to eight times higher than commercial sensors and 75 percent higher than many other carbon nanotube sensors.”   

The breakthrough could lead to a number of potential applications including integrating the sensors into bedsheets to monitor the quality of sleep or into shoes to track step count and posture.

The researchers also said the sensors could also be used in soft robotics to facilitate advances in the production of responsive, self-correcting artificial muscles.

“Most projects don't have this many possible applications,” DeGraff said. “This material could be used in structural health monitoring, wearable technology and everything in between.”

“I'm excited because this is something that can affect a lot of people in their everyday lives,” he added.

The researchers now plan on improving the thinness of the material so that it can be integrated into comfortable and non-restrictive clothing.

They also will conduct additional testing on complex model structures required to ensure the material’s ability to conform to the variable curves and crevices of the human body.

The study was published in Materials & Design.      

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