•••8••• Innovationen Monitoring tire wear Novel inexpensive printed sensor reduces fuel consumption These tiny cylinders of carbon at- oms just one-billionth of a meter in diameter can track millimeter- scale changes in tread depth with 99 per cent accuracy. With two patents pending, the researchers are in the process of establishing industry collaborations to bring the technology to market. “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 gath- ered from the only part of the ve- hicle that is actually touching the road,” said Aaron Franklin, asso- ciate professor of electrical and computer engineering at Duke. “Our tire tread sensor is the per- fect marriage between high-end technology and a simple solu- tion.” The technology relies on the well- understood mechanics of how electric fields interact with me- tallic conductors. The core of the sensor is formed by placing two small, electrically conductive elec- trodes very close to each other. By applying an oscillating electri- cal voltage to one and grounding the other, an electric field forms between the electrodes. While most of this electric field passes directly between the two electrodes, some of the field arcs between them. When a material is placed on top of the electrodes, it interferes with this so-called “fringing field”. By measuring this interference through the elec- trical response of the grounded electrode, it is possible to deter- mine the thickness of the material covering the sensor. While there is a limit to how thick a material this setup can detect, it is more than enough to encompass the sev- eral millimeters of tread found in today’s tires. And with evidence of sub-millimeter resolution, the technology could easily tell driv- ers when it’s time to buy a new set of tires or give information about uneven and often danger- ous tire wear by connecting many sensors in a grid to cover the width of the tire. Tests also proved that the metal mesh embedded within tires does not disrupt the operation of the new sensors. “When we pitch this idea to industry experts, they say to each other, ‘Why haven’t we tried that before?’” said Franklin. “It seems so obvious once you see it, but that’s the way it is with most good inventions.” The best results were obtained by printing electrodes made of metallic car- bon nanotubes on a flexible poly- imide film. Besides providing the best results, the metallic carbon nanotubes are durable enough to survive the harsh environment inside a tire. The sensors can be printed on most anything using an aerosol jet printer – even on the inside of the tires themselves. And, while it is not yet certain that direct printing will be the best manufacturing approach, what- ever approach is ultimately used, Franklin said the sensors should cost far less than a penny apiece once they’re being made in quan- tity. Franklin’s group also wants to explore other automotive applica- tions for the printed sensors, such as keeping tabs on the thickness of brake pads or the air pressure within tires. The sensor is placed on the inside of the tire, where the tire wall and tread interferes with an electric field that arcs between two electrodes. That interference can be measured to determi- ne the thickness of the rubber with millimeter accuracy. Photo: Joseph Andrews, Duke University Continued from page 1 medienformer .de Dürfen wir vorstellen: das TechTeam von Hella Gutmann Solutions. Unser Expertenteam aus praxiserprobten Schraubern versorgt freie Werk- stätten mit wertvollen Tipps, praktischen Tricks und den leistungsstarken Diagnoselösungen und Tools von Hella Gutmann. Kommen Sie doch gleich mal bei uns in Halle 9.0 / Stand A88 vorbei und erfahren Sie mehr über unser TechTeam. Denn zusammen sorgen wir dafür, dass für Sie bei jeder Reparatur mehr rum kommt: mehr Entspannung, mehr zufriedene Kunden und mehr Umsatz. Bis gleich am Stand von HELLA und Hella Gutmann. Übrigens: mehr vom TechTeam gibt es ab jetzt auch unter www.hella.com/techworld www.hella-gutmann.com Das TechTeam kommt Unsere Experten bringen Ihre Werkstatt auf Touren