Worried that I would become the recipient of incessant emails extolling the merit of elegant crystal decanters and pithy advice on how to choose the perfect shrimp fork, I decided to give out my fifteen-year old aol email address (which I have pretty much completely surrendered to spam bots). Typing “aol.com” in my browser to complete verification took me back to the days of dial-up modems. Remember the hauntingly beautiful series of sounds that indicated you were about to engage with the Internet? “eeeeeeeeeeeaaaahhhhwwwwwww eeeeeeeeaahahhhhhhhhwwwwww eeeeeeeeeeahhhhhhhhhwww uhuhuhuhuhhhhhhh tttttttttt ‘you’ve got mail!'” Remember how it took forty five minutes to check your email?

These days, most of our information travels at insane rates of speed along optical fibers only three times as thick as human hair.  Current fiber optics “transmit over a terabyte – the equivalent of 250 DVDs – of information per second” (Physorg.com). That seems like an awful lot of data in a very short amount of time, but just think about what we’d get up to if we could transmit even more!

Image credit Pineda Zuniga

Our current optical fibers are limited by their glass cores. The problem is that atoms in glass are arranged rather haphazardly, and the material by and large is not a semiconductor.  Researchers at Penn State led by John Badding suspected that a crystalline substance – specifically, zinc selenide – is a semiconductor capable of allowing light to be transported over longer wavelengths (i.e. mid-infrared) because the atoms in crystals are orderly and organized.  The team used an innovative high-pressure chemical-deposition technique to deposite zinc selenide waveguiding cores inside of silica glass capillaries to form a brand new class of optical fibers (Physorg.com).

Image credit wikimedia commons

The new optical fibers were more efficient at converting light from one color to another, and they provided more versatility not just in the visible spectrum, but also in the infrared – electromagnetic radiation with wavelengths longer than those of visible light. This is a very cool development because it may represent a step towards making fibers that can act as infrared lasers (good for military applications and corrective eye surgery) and because the technology may also allow us to detect pollutants and environmental toxins more easily (Physorg.com). The idea is that we could transport light over long wavelengths through the atosphere, looking for substances that absorb the long wavelength light. Better fiber optics means richer, faster, and more accurate transmission of information, and that is exciting, don’t you think? It might be even more exciting than hearing “you’ve got mail!”

WU XING:

I have filed this new development under FIRE because fiber optics transmit information with light.

Cited:

“New Kind of Optical Fiber Developed.” Physorg.com. 02/25/11. Accessed 02/28/11. URL.

Stairs are challenging enough for adults at times, but I distinctly remember how hard it was to climb them when I was little.  When you are small in stature, 7″ high risers hit at mid-thigh and most of the time you have to take each stair on all fours.  Many of the epic, all-out “Alli versus the Stairs” battles ended with a small, defiant child celebrating wildly on the second floor, but sometimes things didn’t go my way.  On the days that the straight run, open tread, carpeted monster was my Waterloo, I would find myself tumbling head over heels, going bump bump bump all the way down, only to find myself sprawled out on the ground floor covered with scrapes and rug burns.  But here is one of the things that makes being a living creature so incredible and fantastic: I didn’t have to wait for someone to come patch my skin up after an accident on the stairs.  Because  – wait for it – skin heals itself.

Until recently, most materials we’ve used for building structures have been incapable of significant self-repair.  When the roof of a stadium collapses due to the immense weight of drifting snow, the structure just waits for us to come fix it.  But now some researchers working at Arizona State have developed a “self-diagnosing, self-healing material that can sense the presence of damage and regenerate itself…. Like a biological structure, this “autonomous adaptive structure” could be used to develop usable composites that are self-healing, halting the progression of cracks or damage and regenerating material wherever needed to re-strengthen the structure” (Dillow).  Materials that can find and repair their own scrapes and rug burns will last longer and look better while they last: think of the concept as an anti-aging strategy for buildings.

Image courtesy pingmag.com

The autonomous adaptive structures coming out of Arizona State are made from “shape memory” polymers embedded with a fiber-optic network.   When the material tears or is otherwise damaged, the fiber optic network detects the problem.  An infra-red laser transmits light through the network, delivering heat to the affected area.  The shape memory polymers return to a pre-defined shape when they reach a certain temperature, so the heat from the fiber optic network can be used to close up cracks and tears in the material.  This allows it to regain up to 96% of its original strength.  The shape memory polymers are programmed to toughen up to 11 times, and self-healing action can take place while the material is operational (Dillow).  If the roof of the Metrodome had been able to toughen in response to deformation while self-healing rips and tears, the Vikings might have been able to play there this week.  On a side note, Bret Favre’s body has apparently lost its self-healing capabilities.

Image courtesy popsci.com

More relevant, this week at MIT scientists have at last been able to mathematically model shape-memory polymers in detail, meaning that “applications like implantable medical devices or space materials that can be compacted into tiny packages and then automatically expanded into complex structures once they’re aloft” are now possible (Dillow).  The video below illustrates how shape memory polymers work.  I applaud the display of materials science awesomness coupled with school spirit.

WU XING:

I’ve filed self-healing polymers under Fire and Wood because of the lasers and the flexibility of the shapes.

Cited:

American Institute of Physics. “Self-healing autonomous material comes to life.” ScienceDaily 7 December 2010. 13 December 2010.  URL.

Dillow, Clay. “New Self-Healing Materials Detect when They’re Damaged and Fix Themselves.” Popsci.com 12/09/10.  Accessed 12/13/10.  URL.

Yesterday I learned that researchers at MIT have developed functional plastic fibers that can detect and produce sound.  As you can imagine, my coffee cup almost instantly hit the carpet.  After I wiped up the spill, I dug a little deeper to find out what this singing fiber business is all about. 

It seems that the new acoustic fibers are composed of a conducting plastic commonly used in microphones that contains graphite, the same material found in pencil lead and in my leg, from the time when I accidentally stabbed myself with a pencil in my sleep.  (Have I mentioned that I can be a little bit accident-prone?) To make fibers, long strands are drawn from a heated “preform,” (a large cylinder of a single material) and are then cooled. 

The fibers “derive their functionality from the elaborate geometrical arrangement of several different materials, which must survive the heating and drawing process intact.  By playing with the plastic’s fluorine content, the researchers were able to ensure that its molecules remain lopsided — with fluorine atoms lined up on one side and hydrogen atoms on the other — even during heating and drawing.  The asymmetry of the molecules is what makes the plastic “piezoelectric,” meaning that it changes shape when an electric field is applied to it” (Hardesty).  In other words, the composition of the plastic allows it to retain its useful properties throughout the process of forming it into thin strands.

Because the conducting plastic used by the researchers maintains a higher viscosity (stays thick) when heated, it allows the scientists to draw out fibers with uniform thickness.  They then apply an electrical field that is – get this – 20 times as powerful as the fields that cause lightning during storms – to the plastic in order to align all the piezoelectric molecules in the same direction.  If the fibers aren’t uniform, the electric field would generate a tiny lightning bolt!!

Photo: Research Laboratory of Electronics at MIT/Greg Hren Photograph

Despite the inherent challenges of the manufacturing process (incidental lightning and so on) the researchers built fibers that you can actually hear when you connect them to a power supply and cause them to vibrate.  As the frequency changes, the fibers emit different sounds (Hardesty).  The fibers are incredibly sensitive to vibration, which means they are capable of responding to changes in their surrounding environment.

The potential applications of these acoustic fibers include wearable microphones and biological sensors, loose nets that monitor the flow of water in the ocean and large-area sonar imaging systems with high resolutions.  Fabric woven from acoustic fibers would provide the equivalent of millions of tiny acoustic sensors, which could be used to create clothes that act as sensitive microphones for capturing speech or monitoring bodily functions.  Tiny fiber filaments could measure blood flow in capillaries or pressure in the brain (Hardesty).  These fibers are fantastic, and (AHEM) I’d love to get my hands on some!

More information:“Multimaterial piezoelectric fibres.” S. Egusa, Z. Wang, N. Chocat, Z. M. Ruff, A. M. Stolyarov, D. Shemuly, F. Sorin, P. T. Rakich, J. D. Joannopoulos, and Y. Fink. Nature Materials, 11 July 2010.

Provided by Massachusetts Institute of Technology (news : web).

WU XING:

I’m categorizing these fibers under WOOD because they’re plastic, and FIRE because of the heat and electric field required to make them.

Cited:

Hardesty, Larry. “Fibers that can hear and sing.” Physorg.com. 07/12/10.  Accessed 07/13/10.  URL.