July R&D Round UpJuly 13, 2012 By: Melanie Martella, Sensors
To distract those of us who are dealing with temperatures that feel more like surface-of-the-sun rather than Glorious Summer, how about some neat sensor-related research? This month we've got a biologically inspired technology to let robotic eyes act more like human ones and a new microchip that generates terahertz waves.
When it comes to artificial muscles, piezoelectric materials possess at least some of the desired characteristics: they will expand or contract when electricity is applied, however they won't expand or contract very much, and if you're trying to create a biomimetic actuator, you need much larger motions. Researchers at the George W. Woodruff School of Mechanical Engineering at Georgia Institute of Technology (led by Ph.D. candidate Joshua Schultz under the direction of assistant professor Jun Ueda) have found a way to overcome this limitation. They've connected piezoelectric stacks with strain amplifying mechanisms (to give them larger displacements) and then combined the stacks into a nested hierarchical structure. This allows them to actuate sets of stacks; similar to the way our muscles incorporate sub-groups of muscle fibers (called motor units) that actuate (or not) depending on what we're doing. That's pretty nifty, right? But they didn't stop there! As you can read in greater depth in the article, "Robot Vision: Muscle-Like Action Allows Camera to Mimic Human Eye Movement" they wanted to demonstrate these capabilities, so what they've done is to apply their novel piezoelectric cellular actuator to a camera positioning system to replicate the way we use muscles to focus our eyes. So clever!
What you're trying to do, whether it's seeing inside the human body or transmitting data from here to the moon, determines the frequency of the electromagnetic waves you're using to accomplish the task. Terahertz waves are a promising tool for seeing through lots of different materials without causing the havoc and damage that X-rays can cause and this turns out to be handy for all kinds of food safety, scientific, and medical applications, including the ever-popular airport body scanners. However, many terahertz sources are big and expensive and if you're trying to create something portable and cheap(er), then a smaller, cheaper source is a necessity, which is where researchers from Cornell University come in. Led by assistant professor of electrical and computer engineering Professor Ehsan Afshari, the researchers have developed solid-state devices that couple a ring of oscillators together and tune the resulting harmonics to generate terahertz waves within a narrow frequency band. I'd suggest reading the article, "Solid-state terahertz devices could scan for cancer" for a more detailed description of just how these CMOS devices operate.
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