November R&D Round UpNovember 13, 2009 By: Melanie Martella, Sensors
This month we have chemical sensors designed to fit inside your cell phone, contact lenses that double as heads-up displays, and surface plasmon resonance sensors with multiple channels.
Sniffing Smart Phones
Chemical sensors could be coming to an iPhone near you, at least if the researchers from NASA Ames Research Center have anything to say about it. Led by Jing Li, the team have developed a proof of concept chemical sensor designed to plug into an iPhone and detect airborne ammonia, chlorine, and methane. The postage-stamp-sized device combines a multi-channel silicon-based sensing chip that incorporates 64 nanosensors with a sample jet sensing system and supporting electronics. You can read more (and, more importantly, see the pictures, here). Many research projects have sought to combine additional sensors with cell phones for a variety of applications, including urban pollution, but this may be the slickest I've seen.
Look Into My Eyes
As a long-time wearer of contact lenses, I'm really not sure whether I'm intrigued or squicked out by the article "Contact lenses to get built-in virtual graphics" that appeared in New Scientist. I think intrigued is winning. The gist of the article is that Babak Parviz at the University of Washington, in Seattle, had the bright idea to incorporate a heads-up display into a contact lens, thus enabling a much wider field of view (a limitation with the current systems). The prototype, which has been fitted to a rabbit, is powered by a loop antenna but manages to fit power management circuitry and a tiny LED into crevices within the lens all (so they say) without obscuring the field of view of the wearer. While it's many years away from commercial use, the mere fact that Parviz and his team have achieved this much is, frankly, mind-boggling.
Sculptured Thin Films for Multichannel SPRs
Surface plasmon resonance (SPR) sensors use light to instigate an electromagnetic wave—called a surface plasmon-polariton wave—that moves along a metal/dielectric sandwich and that can be altered by exposure to chemicals or surface irregularities, to name but two. As a result, the sensors are currently used for chemical detection and for certain types of surface microscopy. However, because of the way they work, they're limited to detecting one chemical species per sensor. Thanks to Akhlesh Lakhtakia of Pennsylvania State University that may change. Lakhtakia and his fellows experimented with propogating several surface waves on the substrate (for a far more detailed explanation of exactly what they did and why, I refer you to "Sculptured Materials Allow Multiple Channel Plasmonic Sensors" from Science Daily.) Rather than using the traditional metal/dielectric material, the researchers used a sculptured nematic thin film. Using these materials in a standard SPR sensor set up produced not one but three surface plasmon-polariton waves. Different materials also resulted in more than one wave. Same sensor, same general technology, but now the device can be sensitive to more than one chemical species, say.
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