A SMART Sensor01.04.2011 | Engineering, Faculty, Research
Kauffman and senior research physicist Doug Wolf created the SMART (Status and Motion Activated Radiofrequency Tag) sensor under FAA funding for use in "smart clamps" to hold aircraft wiring in place. Designed to replace traditional clamps, the new technology uses a simple and inexpensive radiofrequency identification (RFID) tag that will "talk" to a handheld reader if a clamp has been compromised, putting the wires – and thus the aircraft – at risk.
A typical commercial aircraft has miles of wiring secured in bundles by hundreds of thousands of clamps, Kauffman said. By keeping bundled wire secure and out of the way, the clamps also keep wires from rubbing against one another or against the aircraft fuselage – which could lead to a break in the insulation. An exposed wire could prove catastrophic because of its potential for sparking, Kauffman added, especially if it is in the presence of fuel.
But clamps can wear and break over time, and wires can get pinched between the clamp ends when they are first tightened. Either way, there is a danger that a wire or its insulation could fray or break, said Kauffman, who was a principal investigator in the 1996 crash of TWA flight 800 outside of New York City. He believes a frayed fuel-sensor wire likely played a significant role in the explosion that brought down the plane.
Finding broken clamps can be tricky because of the sheer volume of clamps within an aircraft, and because they are often in locations not easily accessible to maintenance personnel, Kauffman said. "So we started looking for a way to quickly and easily find out if a clamp broke or did not fully close properly in the first place, and came up with the idea of using RFID tags."
Radiofrequency identification tags are commonly used to track packages and devices such as anti-theft tags on clothing and other consumer goods. An RFID reader sends out radio waves to a microchip sensor embedded in the tag. The sensor's antennae grab the radio waves to power the microchip, so it can in turn send stored information back to the reader.
But Kauffman modified the tag to include a bypass around the chip, preventing the chip from being read unless the bypass is broken.
"RFID tags are designed to always respond, which means they'll keep talking until they fail," he said. "The SMART sensor works oppositely. We call it status-activated, because it will only talk if there is a change in the status of the sensor. In other words, it can only be read if it the sensor bypass is breached."
The modification would allow maintenance personnel to quickly pass a handheld RFID reader through the body of an airplane to listen for broken clamps, Kauffman said, adding that SMART clamps could be used throughout a plane or installed only in 'hot spots,' such as near hydraulic lines, fuel tanks or anywhere else a loose wire could jeopardize the aircraft.
"If we used traditional RFID technology, thousands of good clamps would be talking, making it very difficult to find a broken one among them," Kauffman said. "Using SMART sensors, as long as the reader does not get a signal, all is well. If you get a signal, the tag's identity enables you to quickly find the broken clamp."
That same technology could be used to tell if a composite aircraft panel has sustained a sub-surface crack or, in a completely different venue, whether a football player has suffered a blow to his helmet severe enough to cause a concussion, even if he doesn't show symptoms, Kauffman said. "With only minor variations to the design or material of the microchip bypass, SMART sensors could be used to detect and report hidden impact damage, cracks, temperature changes, corrosion or tampering in any number of products and devices."
Kauffman said SMART components, at less than 50 cents per tag, are already inexpensive enough that they could be manufactured and placed inside existing as well as new football helmets. Concussions have become a growing problem among young and professional ballplayers alike because of their rising numbers, lack of clear-cut symptoms, and mounting evidence of longer-term damage than previously thought, he added. "With SMART sensors designed for impact detection, football helmets used by Pee Wee and professional leagues could be quickly scanned after every practice and any time a player takes a hard hit," he said. "The sensors could be designed to measure different levels of impact, depending on the size of the players, and would only talk to the reader if a helmet sustained enough force to be dangerous."
The sensors would also report which players are tackling with their heads instead of their shoulders, Kauffman said. "Today's helmets are so durable that kids are diving into tackles head first, instead of using their shoulders. It's one of the reasons for the rise in concussions among young and professional players alike. Teaching players to tackle properly could reduce the number of serious injuries on the field."
SMART technology could also make it difficult for identity thieves to steal personal information from electronic passports, which have been issued by the U.S. since 2007, Kauffman said. "Right now anyone with a miniature reader can stand close to you and scan your unprotected e-passport while it's closed and in your pocket or purse. But a passport that contained a SMART tag rather than a traditional RFID tag could only be scanned when opened, allowing appropriate personnel to read it."
Numerous other potential uses include detection and report of: tampering with electronics, wine seals, pharmaceutical containers and other packaging; exposure to temperatures not safe for vaccines or frozen foods – even briefly – during storage or transit; unsafe tire tread wear; and hidden corrosion in equipment and structures such as aircraft and bridges, or biocorrosion in fuel and foods that have become contaminated.
In 2008, Kauffman developed self-healing wire for aircraft and other electronic applications under the same FAA aging-aircraft program that funded SMART sensor technology, which has a patent pending. Self-healing wire was named one of the top 100 "most technologically significant new products" of the year by the editors of R&D Magazine in 2009. During the last 15 years, Kauffman has patented and commercialized – domestically and internationally – a wide range of technologies that have brought in more than $1 million to the Research Institute. He is currently identifying licensees to bring variations of the SMART technology to market.