Xin Zhang’s metamaterial overcomes sweat, salt water, and security challenges
Good news for data-conscious athletes, and anyone interested in their health: A groundbreaking new textile metamaterial developed at Boston University promises to revolutionize the wearable fitness tracker industry, enabling more accurate data collection with greater flexibility. This metamaterial—a material designed to have properties not found in nature—can be patterned onto clothing to create a battery-free network of sensors, monitoring heart rate and other vital signs while blocking extraneous signals, and maintaining function even when the textile is exposed to water (including salt water). The BU team, led by Distinguished Professor of Engineering Xin Zhang (ME, ECE, BME, MSE), published their findings in Nature Communications.
“Imagine a sophisticated network of sensors seamlessly integrated into your clothing, constantly tracking your body’s signals in real time,” says study co-author Xia Zhu (ENG’26), a doctoral student in Zhang’s lab. “Whether you’re pushing your limits during a marathon, swimming laps, or simply going about your daily routine, this network provides a wealth of information without interrupting your activities.”
The challenge with fitness tracking sensors currently on the market is the difficulty connecting them to a central device like a smartphone. Wireless technology such as Bluetooth and Wi-Fi are commonly used, but these often drain the phone’s batteries and present security risks. Near-field communication—the same technology that powers mobile payments—is a promising alternative, but it has limited range and is sensitive to environmental factors such as water and sweat.
To overcome these challenges, Zhang’s team—which also includes Ke Wu, a postdoctoral fellow in Zhang’s lab; Xiaohang Xie, a graduate student in Zhang’s lab; and Stephan Anderson, a professor of radiology at the BU Chobanian & Avedisian School of Medicine—has designed a cutting-edge body-area network (BAN) composed of textile metamaterial patches crafted from coaxial cables (the same cables that bring you internet and TV signals). The patches can be seamlessly embroidered into clothing in any custom pattern, the researchers say.
“Our system enables the smartwatch to continuously monitor physiological signals emitted from my left arm even when I am wearing the smartwatch on my right wrist,” says Zhu. “The smart textile allows the signal to be easily transmitted through the smart clothing in the form of a surface wave. And such a signal stream remains robust and accurate even when I am swimming, taking a shower, or just running outdoors on a rainy day, a very rare characteristic in the field of smart textiles.”
Zhang adds, “Having studied metamaterials for many years, I’m always eager to apply them to solve practical problems. It’s exciting to see our metamaterial technologies addressing real-world challenges in wearable technologies at a system level.”
The study was supported by BU’s Rajen Kilachand Fund for Integrated Life Sciences & Engineering.
Runner photo by Filip Mroz