UBC doctoral student Hossein Montazerian takes a close look at a tiny sensor embedded into a fiber.

Researchers at University of British Columbia Okanagan’s School of Engineering have developed a low-cost sensor that can be interlaced into textiles and composite materials. While the research is still new, the sensor may pave the way for smart clothing that can monitor human movement. The embedded microscopic sensor is able to recognize local motion through the stretching of the woven yarns that are treated with graphene nanoplatelets that can read the body’s activity, explains Engineering Professor Mina Hoorfar.

“Microscopic sensors are changing the way we monitor machines and humans,” said Hoorfar, lead researcher at the Advanced Thermo-Fluidic Lab at UBC’s Okanagan campus.

“Combining the shrinking of technology along with improved accuracy, the future is very bright in this area.” This ‘shrinking technology’ uses a phenomenon called piezoresistivity — an electromechanical response of a material when it is under strain. These tiny sensors have shown great promise in detecting human movements and can be used for heart-rate monitoring or temperature control.

Her research, conducted in partnership with UBC Okanagan’s Materials and Manufacturing Research Institute, shows the potential of a low-cost, sensitive and stretchable yarn sensor. The sensor can be woven into spandex material and then wrapped into a stretchable silicone sheath. This sheath protects the conductive layer against harsh conditions and allows for the creation of washable wearable sensors.

While the idea of smart clothing — fabrics that can tell the user when to hydrate, or when to rest — may change the athletics industry, the sensor has other uses as well. It can monitor deformations in the fiber-reinforced fabrics currently used in advanced industries such as automotive, aerospace, and marine manufacturing.

The low-cost stretchable composite sensor has also shown high sensitivity — it can detect small deformations such as yarn stretching as well as out-of-plane deformations at inaccessible places within composite laminates.

The testing indicates that further improvements in its accuracy could be achieved by fine-tuning the sensor’s material blend and improving its electrical conductivity and sensitivity. This can eventually make it able to capture major flaws like “fiber wrinkling” during the manufacturing of advanced composite structures such as those currently used in airplanes or car bodies.

“Advanced textile composite materials make the most of combining the strengths of different reinforcement materials and patterns with different resin options. Integrating sensor technologies like piezoresistive sensors made of flexible materials compatible with the host textile reinforcement is becoming a real game-changer in the emerging era of smart manufacturing and current automated industry trends,” said Professor Abbas Milani, director of the UBC Materials and Manufacturing Research Institute.