Sensors Mag

March R&D Round Up

March 5, 2010 By: Melanie Martella, Sensors

E-mail Melanie Martella

This month we've got an energy conserving artificial foot developed at the University of Michigan; using ultrasound to asses the properties of leaves courtesy of researchers at the CSIC Institute of Acoustics in Madrid, Spain; and the ability to turn your skin into a touchscreen, as discovered by researchers at Carnegie Mellon University.

Foot Power
Although modern lower-leg prosthetics are now much smarter and lighter than they've ever been before, amputees using them still have to exert a lot of extra energy to shift the artificial appendage around. The human body has spent a lot of time and effort to streamline and optimize the efficiency of bipedal motion. Walking normally involves a symphony of automatic systems working together to keep us upright, balanced, and moving smoothly. For amputees, however, using a prosthetic foot means a 23% increase in expended energy just to walk around. A prototype prosthetic foot developed at the University of Michigan by Art Kuo and Steven Collins, can drop this energy to 14%, almost a 50% reduction. Art Kuo and Steven Collins created a prototype artificial foot that captures the energy dissipated when the foot strikes the ground and then feeds it back into the system at just the right time to enhance the push off from the ankle. Make sure to follow the link for more information and to see a video of the foot in action.

Listening to Leaves
If you want to assess how healthy a plant is, check its leaves. More specifically, check their moisture content, which can provide detailed information on their level of develoment, state of health, and how they're reacting to the environment around them. Now, Spanish researchers Tomas Gómez Álvarez-Arenas, D. Sancho-Knapik, J. J. Peguero-Pina, and Eustaquio Gil-Pelegrín from the Institute of Acoustics in Madrid, have published a paper in Applied Physics Letters on their nonintrusive technique that uses broadband ultrasonic pulses to measure the moisture content and potential of leaves. As described in "Leaves Whisper Their Properties Through Ultrasound," in, "The technique involves radiating the leaves with broadband ultrasonic pulses (between 0.2 and 2 megahertz), which are emitted through the air from portable devices. In doing so, the leaves start to vibrate and an ultrasonic sensor very similar to the transmitter detects the waves. The signal is then digitalised and the researchers analyse the resonance range, which enables the characteristics of the leaves to be assessed." Because this method is both nonintrusive and gives good and rapid results, agricultural researchers may now have a new tool for teasing out the effects of various environmental parameters on plant health and growth patterns.

Skin Into Touchscreens
Sometimes I'll see stories that make me feel like I'm now living inside a futuristic science fiction movie. And this makes me very, very happy because I am a geek. But I digress. The story that induced the most recent squee-fest is Skinput, the brainchild of CMU's Chris Harrison and Microsoft's Desney Tan and Dan Morris. I'll give you the brief overview here but you really do need to follow the link and watch the videos because they are eye-poppingly cool and the explanations of the technology are excellent. The quick and dirty overview is this: if you tap the skin, the impact sets up acoustic signals within the body. The researchers created a bioacoustic sensing array to identify these impacts and then linked them to a variety of user interfaces that would allow a user to control a mobile device by tapping buttons projected onto his or her forearm or by touching his or her fingers, or some similar motion. It's incredibly elegant.

About the Author: Melanie Martella

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