Engineers Create Small Strands That Sense How and When You Move In Real-Time
Engineers created a thread sensor that can be fitted to the skin to measure movement in real-time, with potential implications for tracking health and performance.
Engineers at Tufts University have created and demonstrated a flexible screw-based sensor that can measure neck movement, providing data on the direction, angle of rotation and degree of head displacement. The discovery increases the potential for thin, inconspicuous tattoo-like patches that, according to the Tufts team, measure athletic performance, monitor worker or driver fatigue, aid physical therapy, improve virtual reality systems and games, and enhance computer-generated imagery in cinematography. The technology, described today (January 29, 2021) in scientific reports, adds to the growing number of yarn-based sensors developed by Tufts engineers that can be woven into textiles, measuring gases and chemicals in the environment or metabolites in sweat.
In their experiment, the researchers placed two threads in an “X” pattern on the back of the subject’s neck. Coated with electric-delivering carbon-based ink, sensors detect movement when threads bend, creating tension that changes the way they conduct electricity. When the subject performs a series of head movements, the cable sends a signal to a small Bluetooth module, which then sends the data wirelessly to a computer or smartphone for analysis.
Data analysis involves a sophisticated machine learning approach to interpreting signals and translating them to calculate head movements in real-time, with 93% accuracy. In this way, sensors and processors track the uninterrupted movement of cables, large devices, or limiting conditions such as camera use, or confinement in a room or lab room.
While algorithms need to be devoted to each location in the body, the principle evidence suggests that thread sensors can be used to measure movement in other limbs, according to the researchers. Leather patches or even shape fitting clothing containing threads can be used to track movement in places with the most relevant measurements, such as in the field, workplace, or classroom. The fact that the camera is not required provides additional privacy.
“This is a promising demonstration of how we can create sensors that monitor our health, performance, and environment in a way that doesn’t interfere,” said Yiwen Jiang, an undergraduate student at Tufts University School of Engineering and first author of the study. “More work needs to be done to improve the range and precision of the sensor, which in this case could mean collecting data from a larger set of threads that are regularly distanced or arranged in patterns, and developing algorithms that improve the quantification of articulated movements.”
Other types of wearable motion sensor designs include a 3-axis gyroscope, accelerometer and magnetometer to detect the movement of the subject in relation to its environment. Such sensors are based on inertia measurements – measuring how the body accelerates, rotates or moves up and down – and tends to be bigger and more troublesome. For example, with another system, to measure head movements, it is necessary to place one sensor on the forehead and another on the neck above the vertebrae. Striking equipment placement can interfere with the free movement of the subject or simply convenience because unconsciousness is being measured.
For situations like on the athletic field, a new thread-based sensor paradigm can be a game changer. By placing thin patches like tattoos on different joints, an athlete can carry motion sensors to detect their movement and physical shape, while thread-based sweat sensors, described in previous research by the Tufts team, also potentially track their electrolytes, lactate and electrolytes. other biological markers of performance in sweat.
On the road, threaded sensor patches can warn of truck driver fatigue or other situations where the tracking operator’s vigilance is critical, monitoring the movement of the head of a person who is going to sleep.
“If we can take this technology further, there may be a variety of applications in health care as well,” Jiang said. “For example, those who research Parkinson’s disease and other neuromuscular diseases can also track the movement of subjects in normal settings and daily life to collect data about their condition and the effectiveness of treatment.”
“The goal in making thread-based sensors is to make them ‘disappear’ as far as people are concerned about wearing them,” said Sameer Sonkusale, professor of electrical and computer engineering at Tufts’ School of Engineering, director of Tufts Nanolab, and author of the related study. “Creating a layered thread capable of measuring movement is a remarkable achievement, made even more important by the fact that Yiwen developed this discovery as a scholar. We look forward to perfecting this technology and exploring its many possibilities. “