Scanning electron microscopy images of carbon ink-coated threads show a straight thread, L, and a bent thread, R, which changes its electrical conductivity -- a quantity that can be used to calculate the degree of deformation. Photo by Yiwen Jiang/Tufts University
Jan. 29 (UPI) -- Engineers have developed a thread-based sensor that, when affixed to a person's neck, can measure the movement of the head -- the direction, angle of rotation and degree of displacement.
The new sensor, described Friday in the journal Scientific Reports, could be used to track athletic performance or monitor fatigue in long-haul truck drivers, among a variety of other applications.
Small and inconspicuous, the thread sensor could be applied as a patch on the skin or woven into clothing.
More than just movement, the thread could be used to identify metabolites in a person's sweat or detect gases and chemicals in the atmosphere, researchers said.
To gauge the technology's potential, researchers at Tufts University used the threads, coated in carbon-based ink, to form a small X on the back of a test subject's neck.
Researchers had the subject perform a series of movements. When the threads bend, the strain alters the weak electric current running through the thread -- different movements alter the current in different ways.
With each movement registered by the sensors, the threads send a signal to a bluetooth device, which beams the data to a computer or smartphone.
Scientists used sophisticated machine learning algorithms to understand the unique effect of different movements on the thread's electric current.
In a follow up test, the algorithm was able to quickly identify the movement of the head -- with 93 percent accuracy -- based on the electric data relayed by the sensor.
"This is a promising demonstration of how we could make sensors that monitor our health, performance, and environment in a non-intrusive way," first study author Yiwen Jiang said in a news release.
"More work needs to be done to improve the sensors' scope and precision, which in this case could mean gathering data from a larger array of threads regularly spaced or arranged in a pattern, and developing algorithms that improve the quantification of articulated movement," said Jiang, an undergraduate student at Tufts
Other types of wearable motion sensors calculate movement internally, using 3-axis gyroscopes, accelerometers and magnetometers to sense motion in real time. Sensors that calculate motion internally tend to be bigger and more cumbersome.
An athlete wearing a series of skin patches made using the new thread sensor wouldn't even know they were there, according to the researchers. And they suggest the new thread patch could be placed on different parts of the body to provide sophisticated analysis of athletic motion and performance.
The patches could also be used to monitor the motion of workers to predict when fatigue is about to set in, potentially preventing workplace accidents.
"If we can take this technology further, there could be a wide range of applications in healthcare as well," Jiang said.
"For example, those researching Parkinson's disease and other neuromuscular diseases could also track movements of subjects in their normal settings and daily lives to gather data on their condition and the effectiveness of treatments," Jiang said.