April R&D Round UpApril 13, 2012 By: Melanie Martella, Sensors
This month we've got tiny, self-sealing air samplers, a gel that could be used to create artificial skin for robots, and even hardier Hall effect sensors. Let's get to it, shall we?
Self-Sealing Air Samplers
Using sensors isn't just a question of choosing the appropriate technology, it's also about taking care with how you make those measurements. For climate scientists, researchers at Sandia have developed a new tool to help the scientists get the best data they can. The tiny, self-healing valve sensors allow researchers to take samples of air (or other vapors) and seal them, uncontaminated, within the device. The phase-change part comes in with how the micro-valve opens and closes. The sample travels through a tiny hole into the sample container. That hole is made in a low-melting-point alloy, such that applying a little heat will cause the alloy to melt. For our tiny little sampler, that means that zapping it with a little heat causes the hole to melt closed, sealing the vapor into the container until it's time to uncork it in the lab. One of the many clever aspects to this particular project is that the devices are small enough and simple enough to be carried on UAVs or weather balloons, expanding the ability of countries to participate in data collection. Better data means better models and better information for decision-making.
Getting Robots to Feel
When you bounce your shin off a coffee-table your skin responds to that mechanical act by producing a number of different chemical signals to tell your brain that a. OW, that hurt and b. oh yeah, you just dinged yourself on the furniture. It turns out that it's quite hard to come up with a man-made material that can mimic the ability to convert a mechanical stimulus into a series of chemical signals. That's where oscillating gels come in, and I don't mean putting jello on a shaker table. A Belousov-Zhabotinsky (BZ) gel produces an oscillating chemical reaction in response to a mechanical stimuli (squish it and the gel goes pulsates as the resulting chemical reaction makes it swell and shrink in response). Freaky, right? That freakiness could be useful in the ongoing quest to develop new sensors and artificial skin for robots, to name two possibilities. It turns out that researchers at the University of Pittsburgh and MIT discovered that you can resuscitate a non-oscillating gel by pushing it hard enough. which means that the gel isn't just a one-time use curiosity. (For more information on the topic, I'd suggest a visit to MIT's Van Vliet Laboratory for Material Chemomechanics Web page, where you can read the actual papers describing the research and its importance.) I love the potential utility, but honestly I'm still jazzed by the fact that there are gels that wobble all on their own.
Making Hall Effect Sensors Even Hardier
Hall effect magnetic field sensors are widely used today, and part of their appeal is that they do their job very, very well; they're tiny; and they're unfussed by many industrial environments. Thanks to researchers at Japan's Toyohashi University of Technology, there now exist Hall sensors that can operate in temperatures to 400°C and in high-radiation environments. The key to these performance enhancements lies in using gallium nitride to construct the sensors. According to the Science Daily article, "Hard Electronics: Hall Effect Magnetic Field Sensors for High Temperatures and Harmful Radiation Environments", the researchers used AlGaN/GaN two-dimensional electron gas heterostructures to fabricate the sensors and give them their impressive temperature and radiation resistance.
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