The sensor uses metallic carbon nanotubes that can track millimeter-scale changes in tread depth with 99% accuracy. If commercialized, the device promises improved vehicle safety, performance, and efficiency.
According to Aaron Franklin, associate professor of electrical and computer engineering at Duke, "With all of the technology and sensors that are in today's cars, it's kind of crazy to think that there's almost no data being gathered from the only part of the vehicle that is actually touching the road."
The researchers see their invention as a "perfect marriage" of high-end technology and simplicity. Described in a paper in the IEEE Sensors Journal - Noninvasive Material Thickness Detection by Aerosol Jet Printed Sensors Enhanced through Metallic Carbon Nanotube Ink - the tire tread sensor contains two closely spaced electrodes, between which an electric field is formed that arcs between the electrodes.
When the sensor is placed on the inside of a tire, the tire wall and tread material interfere with the electric field. The amount of that interference can then be measured to determine the thickness of the tire rubber with millimeter accuracy. Tests showed that metal mesh embedded within tires does not disrupt the operation of the sensors.
As far as the sensor design itself, the researchers found that the best results were achieved by printing electrodes made of metallic carbon nanotubes on a flexible polyimide film. The metallic carbon nanotubes have the durability needed to survive the harsh environment inside a tire. The sensors could be printed on almost anything using an aerosol jet printer, and should cost less than a penny a piece in quantity say the researchers.
"When we pitch this idea to industry experts, they say to each other, 'Why haven't we tried that before?'" says Franklin. "It seems so obvious once you see it, but that's the way it is with most good inventions."
The researchers are exploring other automotive applications for the sensors, such