Sensors Mag

August R&D Round Up

August 10, 2012 By: Melanie Martella, Sensors

E-mail Melanie Martella

OK, how awesome (in the true sense of the word) was the successful landing of Curiosity on Mars? And how jubilant were the people in Mission Control at that successful touchdown? Mad geniuses the lot of them, and I can't wait to see what Curiosity will discover. Now that I've got my moment of squee out of the way, let's talk about some non-space-based technology developments, shall we? This month we have a beetle-inspired strain sensor and a smart knee simulator to provide data on how to protect knee ligaments.

Hairy Yet Sensitive
Nature has many, many clever design ideas and scientist and engineers throughout the ages have made use of some of those concepts to build a wide variety of innovative devices. The latest entry in the list of bio-inspired sensors comes from Seoul National University where engineer Kahp-Yang Suh and colleagues have developed a remarkable and extremely sensitive strain sensor. As described in Katherine Bourzac's Nature news article, "Electronic sensor rivals sensitivity of human skin", the sensor copies a trick from beetle wings. Some beetles use van der Waal's bonds between tiny hairs on their bodies and on their wings to lock the hairs together and thus tether the wings when the beetles are at rest. What Suh and his fellow researchers have done is to create sheets of tiny polymer hairs that are then coated with metal. When two sheets are sandwiched together, the hairs on the sheets lock together in a similar way. Now for the fun part. When you press, twist, or slide along its surface, the sensor experiences changes in resistance as the hairs alter their position. The reason that this particular new sensor is so intriguing is that it's not only very sensitive (it can sense pressures as small as 5 Pa) but it can also distinguish between the types of strain: pressure, torsion, and shear, something that most other strain sensors can't do.

Better Data to Protect ACLs
The anterior cruciate ligament or ACL is one of the knee's four major ligaments and sits behind the kneecap. While no joint injury is ever good, ACL injuries tend to be the worst of the bunch when it comes to knees, as too many athletes can attest. Naveen Chandrashekar, assistant professor of mechanical and mechatronics engineering at the University of Waterloo in Canada wants to create braces to protect the knees of those with ACL injuries and (ultimately) figure out better preventative measures. To that end, he and his colleagues have created a simulator that attaches actuators and sensors to a cadaver knee with its muscles and ligaments intact to measure what happens to the knee (and the ACL) as the knee reacts to the motions involved in running and jumping. The simulator allows the researchers to measure exactly how much stress the ACL experiences for the various activities and this data can then be used to identify athletes who are more prone to ACL injuries, design braces to better protect people who already have ACL injuries, and figure out exercises and other measures to help prevent ACL injuries in the first place.

About the Author: Melanie Martella

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