University of Delaware (UD) engineers are in the hunt to develop next-gen smart textiles. Their approach consists of creating flexible carbon nanotube composites coatings on a series of fibers, such as nylon, cotton, and wool.
Fabric suited with this sensing technology can lead the charge toward future “smart garments.”
The carbon nanofibers release electrical changes in the fabric when squeezed. The coating can reportedly measure a vast range of pressure, from the touch of human hand to the full weight of a moving forklift.
“As a sensor, it’s very sensitive to forces ranging from touch to tons,” says Erik Thostenson, UD associate professor in the Departments of Mechanical Engineering and Materials Science and Engineering.
The nanocomposite coatings “are created on the fibers using electrophoretic deposition (EPD) of polyethyleneimine functionalized carbon nanotubes,” according to UD.
“The films act much like a dye that adds electrical sensing functionality,” says Thostenson. “The EPD process developed in my lab creates this very uniform nanocomposite coating that is strongly bonded to the surface of the fiber. The process is industrially scalable for future applications.”
Current methods, such as knitting metal with fibers, or plating fibers with metal, can create uncomfortable designs. The new coatings measure around 250 to 750 nanometers thick, which according to the research, is 0.25 to 0.75 percent as thick as a piece of paper. Along with the increased comfort, the coating is inexpensive and lightweight.
A suitable application for this tech lies within measuring the forces on patients’ feet as the walk, treating injury, imbalances, and helping with preventative care. Current tests use instrumental treadmills and motion capture in a lab setting, however, patients my change their behavior when walking normally outside. This is why the integrated sensor can relay more accurate gait data, since it can collect information outside the laboratory.
Further applications include sports medicine, assessing movement disorders, and post-surgical recovery.
“Because the low-cost sensor is thin and flexible the possibility exists to create custom footwear and other garments with integrated electronics to store data during their day-to-day lives,” says Sagar Doshi, doctoral student in mechanical engineering at UD, and lead author on the paper. “This data could be analyzed later by researchers or therapists to assess performance and ultimately bring down the cost of healthcare.”
The paper, “Thin and Flexible Carbon Nanotube-Based Pressure Sensors with Ultrawide Sensing Range,” was published in the June issue of ACS Sensors.
Below you can see Doshi (left) and Thostenson (right) testing an elbow sleeve fashioned with their sensing technology.