A team of engineers at the University of Delaware (UD) is developing next-generation smart textiles by creating flexible carbon nanotube composite coatings on a wide range of fibers, including cotton, nylon and wool, an article in Printed Electronics World reports. Their work is documented in ACS Sensors and demonstrates that the sensors have the ability to measure a broad range of pressure—from that exerted by large machinery to the touch of a fingertip.
The carbon nanotubes give the fabric coating its sensing capability. When the material is squeezed, electrical changes in the fabric are measured. The sensing technology is expected to be applied to future smart garments equipped with sensors in the soles of shoes or stitched into clothing to detect the wearer’s motion.
“The films act much like a dye that adds electrical sensing functionality,” said Erik Thostenson, an associate professor in the Departments of Mechanical Engineering and Materials Science and Engineering. He says the EPD process creates a “uniform nanocomposite coating that is strongly bonded to the surface of the fiber.” The materials used to make the sensor coating are said to be inexpensive and require only water as a solvent. Thostenson believes the process is scalable for industry.
The coatings are between 250 and 750 nanometers thick—about 0.25 to 0.75 percent as thick as a piece of paper—and may add about a gram of weight to a garment or shoe. The nanocomposite coating developed is said to be flexible and have a pleasant “feel.” It’s been tested on synthetic and natural fibers, including polyester, Kevlar, Spandex, nylon, cotton and wool.
Sensor-coated fabrics move outside the lab
In the future, sensor-coated fabric could measure forces on people’s feet as they walk. Clinicians could then assess imbalances after injury or help prevent injuries. The technology could also be applied to sports medicine, post-surgical recovery and for assessing movement disorders in children.
One advantage to the sensors is they’re mobile and reflect real life. “. . . We could utilize these novel textiles outside of a laboratory setting—walking down the street, at home, wherever,” said Thostenson.
Sagar Doshi, a mechanical engineering doctoral student at UD, is the lead author of the paper. He was instrumental in making the sensors, optimizing their sensitivity and testing mechanical properties in shoes and sandals. Doshi also wore the sensors in preliminary tests.
Findings suggest the sensors collect comparable data to that collected by a force plate, a laboratory device that often costs thousands of dollars. Less expensive collection of data could “ultimately bring down the cost of health care,” Doshi said.