I’m starting to worry that I’m turning into an ostrich.

I’m territorial and ill-tempered. I’m fighting a strange desire to eat shiny objects. And when I get scared, I find myself hiding my face as though not seeing whatever is scaring me will make it go away. And this may or may not be related: I’m developing a strong aversion to light bulbs.

Image courtesy http://www.ostrichheadinsand.com/

A company called Nth Degree Tech may be able to help me out with that last problem. They’re seeking to replace light bulbs with their first commercial product, a two foot by four foot LED light sheet that’s flat and looks like a glowing piece of paper, which they plan to ship to customers for evaluation by the end of the year (Bullis). This is an exciting development, since it would allow lighting designers to get freaky with curved or unusually shaped light-emitting surfaces – at a price point comparable to the current cost of fluorescent light bulbs and fixtures.

Image courtesy Nth Degree Tech

To make their snazzy new lighting material, Nth Degree workers carve up “a wafer of gallium nitride to produce millions of tiny LEDs—one four-inch wafer yields about eight million of them. The LEDs are then mixed with resin and binders, and a standard screen printer is used to deposit the resulting ‘ink’ over a large surface” (Bullis).  They toss down a layer of silver ink for the back electrical contact, add a layer of phosphors that alter the color of the light emitted by the LEDs from blue to various shades of white, and then they slap on an insulating layer that prevents those pesky short circuits that can burn out the LEDs.

The front electrical contact is made with an ink containing invisibly small metal wires, which makes it transparent and allows light through the layer.  The transparent electrical contact ALONE could be the subject of an entire article, since it’s unspeakably awesome. Its awesomeness derives from the fact that it may eventually replace the brittle and often testy indium tin oxide (ITO) sheets that have been used in touch screens and electroluminescent assemblies in the past. ITO can be expensive, it can’t be printed and it’s not at all flexible – it deserves to be made redundant.

Image courtesy Nth Degree Tech

While printing with inks that are comprised of “tiny working LEDs produces much brighter light than depositing powders or thin films of electroluminescent material,” Nth Degree’s light sheets don’t match the best LEDs available today, which emit over 200 Lumens per watt.  The sheets are better than incandescent lights in terms of efficiency, emitting 20 lumens per watt, but they’re not as good as fluorescent lights just yet, which emit 80 lumens per watt (Bullis).

The new design won’t require heat sinks the way current conventional LEDs do because the lights are distributed evenly and in a thin layer, meaning that they do not get hot.  The downside is that the tiny LEDs need a pretty robust power source and as a result, Nth Degree’s first light fixture will be two inches thick despite the fact that the light-emitting surface is thin and flexible (Bullis).  I’m not letting that ruffle my feathers, however, since I’m betting that the whole assembly will get thinner over time.

WU XING:

Filed under FIRE because it lights up!

Cited:

Bullis, Kevin. “Lighting Sheets Made of Tiny LEDs” Technology Review Online. 10/28/11. Accessed 02/24/12. URL.

I feel quite strongly that pollution is an evil and nefarious menace; it kills plants and animals, probably causes cancer, and coats everything on your street-facing balcony with a layer of dark brown powdery sludge that means you have to toss heavy buckets of water over your white metal patio furniture anytime you have guests over. I’m sure you know exactly what I’m talking about.

1952 | London Smog – Image courtesy ptkeepcalmcarryon.blogspot.com

Anyway – as I mentioned, I am deeply opposed to pollution in many of its forms, and I’m thinking of founding a formal opposition group to host regular meetings following strict Parliamentary procedure. The formal opposition group will commit ourselves as a first order of business to obtaining some newfangled “pollution glue” aka “dust suppressant” that the city of London is planning to spray on “15 separate stretches of road in areas with especially bad air quality” in order to trap pollutants (Price). If left unchecked, these polluting particles will get sucked into the lungs of  innocent bystanders in the widespread and perfectly understandable habit of breathing. This must be stopped.

The pollution glue is a non-toxic, biodegradable, saline solution with calcium magnesium acetate. Converted winter service trucks will spray it on the streets of London at night like so many machine-like dogs marking so many road-like fire hydrants. The glue will have to be reapplied frequently since rain has a tendency to wash the solution away into drains and traffic wears it off the surface of the street.

Image courtesy nj.gov

The dust suppressant can’t trap carbon monoxide or other gas-based pollutants, but it will make it easier to breathe the air around central London: preliminary tests showed a 10-14% reduction in particulate matter with a diameter of 10 micrometers or smaller (Price). The city is in a rush to improve urban air quality because London faces steep fines for violating PM-10 limits set by the European Union.

When I heard about pollution glue, I was all excited because it seems brilliant and tidy to trap nasty particles before we inhale them. Not only that, I thought, the glue is non-toxic so it won’t harm the environment. But then I realized that anything that traps industrial particulates (even if the material itself is not made of nasty chemicals) will essentially become extremely toxic as it rounds up pollutants – and so instead of breathing in evil dust, Londoners may simply be allowing it to run into their watershed in a more concentrated form.

And perhaps more fundamentally, the glue does nothing to discourage industry from emitting the particulates in the first place. What do you think?

WU XING:

I’m filing pollution glue under Fire because fire makes smoke and particles and I sense that pollution glue would be fond of it.

Cited:

Price, Andrew. “A ‘Pollution Glue’ Gets Sticky with Pollution, Improves Air Quality.” fastcoexist.com 01/11/12. Accessed 1/12/12. URL.

Yesterday I bent over in the attempt to tie the absurdly bright purple shoe laces on my almost offensively bright purple sneakers and made a startling discovery: I’m not as flexible as I used to be.  In fact, the overwhelming tightness of my hamstrings makes your standard British upper lip look positively floppy; and as I fired up my smartphone to schedule some emergency yoga I was reminded that I had yet to share an amazing new fully stretchable OLED display recently developed at the University of California, Los Angeles, a place where they know a thing or two about screens.

OLEDs or Organic Light-Emitting Diodes are great technology for screens primarily because they work without a backlight and can display deep black levels for high contrast.  OLED displays can be manufactured thinner and lighter than liquid crystal displays (LCDs) and “in low ambient light conditions such as dark rooms an OLED screen can achieve a higher contrast ratio than an LCD, whether the LCD uses either cold cathode fluorescent lamps or the more recently developed LED backlight. Due to their low thermal conductivity, they typically emit less light per area than inorganic LEDs” (Source: Wikipedia). What it all boils down to is that OLEDs are the bees knees. FACT.

Image courtesy wired.com

Once researchers saw how thin they could make OLEDs it was only a matter of time before people starting thinking about how to make them flexible. Stretchable electronics open up a world where video displays get rolled up and stuffed in your pocket, electronic sheets drape like cloth, electronics grow and shrink on command, and the mighty condor gets taken off the endangered species list.

Early attempts at stretchable electronics resulted in prototypes that connected rigid LEDs with stretchable material and others that bent but couldn’t stretch. The challenge researchers faced was how to ensure that the electrode could maintain connectivity while being deformed since many conductive materials can’t stretch nearly as far as one might like.  Enter the humble yet versatile carbon nanotube: it’s stretchable, conductive, appears transparent in thin layers, and it usually picks up the check after lunch dates.

The fly in the nanotube ointment, so to speak, is the fact that carbon nanotubes must be attached to a surface; the attachment can be tricky to pull off since when applied to a plastic backing nanotubes have a tendency to slide off or even slide past each other when the backing is stretched. To evict said proverbial fly from said proverbial ointment, the UCLA researchers created a carbon nanotube and polymer electrode layered on a stretchable, light-emitting plastic.

The researchers “coated carbon nanotubes onto a glass backing and added a liquid polymer that becomes solid yet stretchable when exposed to ultraviolet light. The polymer diffuses throughout the carbon nanotube network and dries to a flexible plastic that completely surrounds the network rather than just resting alongside it. Peeling the polymer-and-carbon-nanotube mix off of the glass yields a smooth, stretchable, transparent electrode” (Grifantini).  I imagine that the carbon nanotubes embedded in the plastic stretch at roughly the same rate, and that the plastic keeps to itself mostly and doesn’t interfere with the ability of the nanotubes to conduct electricity.

Image courtesy pcworld.com

The team sandwiched two layers of carbon nanotube electrode around another plastic that emits light when current runs through it.  Researchers obtained a laminator from a local office supply store to press the layered device together so that it could be handled safely in the presence of electric current.  As an aside, we did the same thing when we screen printed an electroluminescent lamp in Switzerland this summer and were hoping to not get electroshocked by the circuits. (More on that soon).  In contrast to our electroluminescent display, the flexible OLED created by the UCLA team can be stretched by as much as 45 percent while emitting a colored light.

Their prototype is a two-centimeter square that emits a one-centimeter square brilliant sky-blue light that stretches like silly putty until it loses conductivity due to being stretched too far or too many times (Grifantini).  The researchers also made a prototype using silver nano wires (which are more conductive than nanotubes) that exhibits similar stretching properties but is even more conductive.  Their layered approach is a great idea, not least because it’s easy to imagine how the process could be scaled up for production.  Now if only those scientists could help me with my hamstrings….

WU XING:

I have filed stretchable OLEDs under Water, Wood and Fire because they’re flexible, stretchy, and they light up.

Cited:

Grifantini, Kristina. “The First Fully Stretchable OLED.” Techreview.com 08/26/11. Accessed 10/05/11. URL.

Watch video: Stretchable OLED – Tech Review

Say what you will about the 1990’s, the decade produced some severely under-appreciated and entirely too short-lived cultural moments: I mean, Hammer pants? Titanic? Come on – you know you loved it!  Another phenomenon of the 1990’s that in some ways is slightly less exciting than the OJ Simpson trial, but which has stayed with us to this day is: green-tinted glass.

Image courtesy metaefficient.com

No one knows exactly how it started, but I imagine that sometime in the 1990’s, an architect somewhere in the world specified green-tinted glass for the fenestration on a prominent building. This building was probably published in a print magazine that a lot of other architects read, and somehow, without even knowing what was happening, they all suddenly wanted to use green glass on their projects too.  I completely understand: the exact same thing happened to me when I was reading Elle and saw that Heidi Klum decided to cut bangs (and yes, mine are still growing out).

Image courtesy instyle.com

What if there was a way to have your green glass cake when it felt trendy, and then not have the same cake twenty years later when it was moldy and dated, and kind of sad looking?  I think perhaps there is!

I recently learned that a University of Connecticut scientist has developed a method that allows films and displays to change color.  The obvious application for this technology is sunglasses, and everyone from Hollywood stars to the U.S. military are interested in lenses that respond to changes in the environment to make it easier to see (or be seen).

Typical transition lenses use photochromic films, which are sheets of polymers that change color when light hits them. The new color-changing technology uses electrochromic lenses; these are controlled by an electric current passing through them that adjusts when triggered by a stimulus such as light (Physorg.com). The arrangement is similar to a double-pane window with a gel sandwiched between the glass.

Image courtesy physorg.com

That’s what got me thinking that this material, which can change color as quickly as electricity can travel through it (ie instantaneously) could be great for buildings.  The polymer used by the scientists creates less waste and is less expensive to produce than previous mixtures, which is good because for an architectural application, you’d need a lot of it!

WU XING:

I have filed this under fire because electricity creates the color change, and under wood, because it’s a polymer.

Cited:

“A Better Way to Photo Gray: New Technology Allows Lenses to Change Color Rapidly.” Physorg.com 07/12/11. Accessed 07/15/11. URL.

VergeLabs, an architecture and design practice based in the United Arab Emirates founded as a partnership between Ginger Krieg Dosier and Michael Dosier, brought some of that magic to concrete with their development of Glowcrete.

Image courtesy Vergelabs

The researchers used phosphorescent pigment in two ways to produce glowing concrete: they added the pigment to expansion cement, the pigment, when distributed unevenly, left a glowing trail that served as a record of the mixing process; and they also added the phosphorescent pigment to the concrete as aggregate. The even distribution of pigment in the second case creates a uniform distribution of light emission.

In each case, as the surface of the concrete weathers and erodes, new phosphorescent aggregate is exposed, which extends the lifespan of the luminescence (Source: Vergelabs).  I’d like to learn more about the phosphorescent pigment the researchers used – I’m not sure how long it lasts or whether it’s toxic (although I’d imagine the answers to those questions are: not very and yes).  That being acknowledged, I can so clearly imagine this material at the bottom of a swimming pool or fountain, or even on the underside of an unfinished concrete slab – pure magic.

WU XING:

I have filed glowcrete under Earth (concrete) and Fire (glowiness!)

Cited:

Dosier, Ginger Kreig and Michael. “Glowcrete.” Vergelabs Research in Architecture. 05/30/06. Accessed 06/03/11. URL.

Image courtesy my.firefighternation.com

Manuel Kretzer sent me a description of the project, Material Animation, excerpts from which I’ll share here:

Material Animation is a kinetic light installation made from laser cut electro-luminescent (EL) foils which senses location, number and velocity of human occupants and responds through a multitude of wireless networked components to encourage further interaction with the environment.  It merges advanced techniques in parametric design, digital fabrication, physical computing, electronics and material science with theories and computational approaches to machine intelligence and sets them into a real world context.

The experiment is situated in three rooms of an idle emergency bunker below ETH Zürich’s Science City campus. Each room reflects a different theme and approach to physically animate the distinctive material properties at an architectural scale. Electroluminescent foils are extremely thin, flexible and lightweight screens which emit a homogeneous cold light across their surface without the need for additional infrastructure.

So to recap: you enter an unused emergency bunker (danger! – I told you not to take off your helmet!!) and then wind your way through a series of darkened rooms, each of which contains objects that are not alive, but which can sense your presence and respond.  Each room is equipped with one Microsoft Kinect Sensor, which is usually used to control the Xbox 360 console using gestures and spoken commands. The device features an RGB camera, depth sensor and multi-array microphone, which provide full-body 3D motion, capture, facial recognition and voice recognition capabilities.

The behavior of the elements in each room depends on the number of people present in each room, their location, movement and speed, and if more than two people are in the same room, also the area of space they occupy. The elements encourage people to interact with the installation, allowing the system to collect real-time feedback. Not only that, but the various installations are connected into a network, so that something going on in one room can trigger activity in another.

Vapor

Vapor creates a fluid space consisting of eight floating elements that are expanding and contracting according to location and amount of users. The main focus was to emphasize the lightness of the material and maximize the three dimensional form which is created through the way that two electroluminescent A4 sheets are cut and combined. Generative design processes and the use of parametric software led to an oval shape that allows top and bottom part to reveal and conceal independently from each other. Each element is controlled and animated by two servo-driven pulleys, which are mounted to the back wall of the room. The servos allow for the expansion and contraction of the top and bottom layer and simultaneously raise the element in space. The speed of movement and frequency of illumination are determined by a Java programmed behavior and the real time input of the sensor system, which are then tuned to the overall performance of the other spaces.

Open Wires

Open Wires aims to create an environment based on lighted, ephemeral and unpredictable three-dimensional shapes.  The system consists of 31 EL strips that revolve and flicker in high speed. The strips are attached to the ceiling at two different heights. The first level is overhead, acting as a collective cloud system. The second position is lower and invites the visitors to touch and distort the ray trace. Each element mainly consists of an electroluminescent foil, a square-shaped rotary contact and a DC motor. The motor is fixed to the acrylic structure of the system. Through a metal axis, the rotary contact and the EL foil are attached to the motor. Two fixed open wires power the foil through the rotary contact.  The visual impact of Open Wires is affected by both the revolving speed of the motors and the on/off state of the EL strips. The combination of these two factors forms the unpredictable shapes in space.

Insomnia

Insomnia focuses on the flexibility, thinness and homogeneous illumination of the material. These properties are used to back light two separated optical animations based on moiré patterns. This effect appears when two transparent layers containing coherent opaque patterns are overlapped and moved against each other. Each structure consists of an EL layer, printed black and white pictures and a striped pattern, which slides horizontally. The project was approached from three sides. First the flexibility and pliability of the material was explored. Second the optical illusion resulting from the moiré effect and how it tricks and stimulates human perception was analyzed and reproduced. Third a structural and mechanical system was developed that would incorporate and unify the various layers.

Disturbance

Disturbance generates a vividly vibrating structure that appears and disappears and invites the users to pass through and linger among its suspended tentacles. The piece consists of 64 thin electroluminescent strips, which are evenly spread along a circular disk that is fixed to the ceiling of the space. While lit, they form a cylindrical surface that blurs and shivers when it’s being hit by the fast spinning propeller that sits in the center of the disk. Depending on the proximity and location of approaching people light patterns gradually appear and disappear along the round surface. As with the other installations, the piece is networked and adopts its behavior to situations happening in the different rooms.

The project is a case study in the possibilities of Electroluminescence, an optical phenomenon in which light is emitted by a material in response to a strong electric field.  Material Animation used EL foils, which are extremely flexible, lightweight, thin screens that can be described as:

flat light bulb sandwiches consisting of layers of conductive and non-conductive plastic and a layer of phosphor. Light is produced when an electric current is passed through a semiconductor with tiny holes. As the excited electrons pass over these holes, they release their energy as photons, which result in a steady glow of the material.  Compared to other lighting technologies electroluminescent lights require very little alternating current but a relatively high voltage (between 60 and 600 volts).  In contrast to neon lamps, filament lamps or LEDs, electroluminescent light is non-directional, so the brightness of the surface appears consistent from any viewing angle. The emitted light is perfectly homogeneous and visible from a great distance. Because EL sheets are self-contained, there is no further infrastructure needed for installation.

WU XING:

I have filed Material Animation under Fire because of the EL components and all the electronics involved in this fascinating project. Special thanks to Manuel Kretzer for all the info!

Cited:

Kretzer, Manuel. “Material Animation.” CAAD ETH 2011. (Text Excerpts and Images unless noted otherwise).

Image courtesy thenewyorkgreenadvocate.blogspot.com

The Lumenatrix Backlighting System by Duo-Guard aims to remedy at least the energy consumption issue by providing an LED-based architectural lighting system that allows designers to create free standing, smoothly illuminated architectural elements such as walls and ceilings without hot spots.

The Lumenatrix system is comprised of tiles (squares, hexagons, octagons, or rounds that can be custom-fabricated in 2″-12″ depths) supplied individually or in prearranged configurations.  The tiles can be recessed, surface, or pendant mounted, and they’re capable of transmitting daylight, which reduces the cost of a glowing wall during daylight hours.  The tiles are arranged in panels that consist of a structural power rail grid system that provides low voltage electricity to the LEDs.  The lights can slide on the rails to produce specific lighting effects.

Image courtesy thenewyorkgreenadvocate.blogspot.com

Heat sinks allow the system to run at lower temperatures, which theoretically increases the lifespan of the LED bulbs, and with one LED per square foot of illuminated surface, the power consumption of the system can be as low as 1-3 watts per square foot.

Check out the following video produced by Duo-Guard for Greenbuild last year to learn more about the system!

WU XING:

I have filed Lumenatrix Backlighting system under Fire, since it involves lighting.

Cited:

Lumenatrix Site

And now, since you are probably wondering how on earth ebooks would be keeping me from spending long hours poolside engoldening myself, let me explain the difference between Kindle for iPhone and Kindle for … er … Kindle. Display screens on phones are typically LCD or OLED, and they don’t do well in sunlight. I’m not sure exactly why that is, but suffice it to say the screens are neither bold nor brilliant under typical pool-day conditions.  In contrast, e-readers like the Kindle use black and off-white electronic paper, which is purported to be easy on the eyes and performs much better in the great outdoors.

Image courtesy ebooknews.com

While it will take years for electronic ink manufacturers to develop color technology that matches LCD screens, E-Ink Holdings, the company that makes the electronic paper for Amazon’s Kindle e-reader, has been experimenting to extend their existing black and white display technology further. E-Ink Holdings recently announced that they can now print digital displays onto conventional cloth, as well as on “the rip-stop material Tyvek that’s used in yacht sails and toughened envelopes” (Eaton).  E-Ink’s new technology is ready for incorporation into products.

While it’s not as high-resolution as a fully pixelated e-ink screen that you’d see on an e-reader; rather, the cloth displays are segmented, ultra-thin, rugged, and flexible (SURF). The system works well in situations where it can flash on and off, but “presumably there’s not much stopping E-Ink from cleverly engineering it into a more complex array that emulates a basic 15-segment alphanumeric-capable display. And more precise pixels may be possible – making for a low-resolution black and white display on cloth” (Eaton). So yes, we are talking about wearable electronic display screens!

I can see this material being used so many ways, and in so many places in buildings and other structures – for instance, curtains and fabric-covered wall panels or ceilings that flash messages in emergency situations or display advertising. The SURF e-ink could also lend itself to t-shirts that alternate between the words “sexy” and “dance party” – which, based on a recent trip to Paris, I suspect would be wildly popular with 80% of the population of France. The possibilities are endless.

WU XING:

I have filed E-ink on Cloth under wood because it is flexible, and under fire because it can be controlled electronically.

Cited:

Eaton, Kit. “E-Ink on Cloth Raises the Terrible Prospect of T Shirt Ads.” FastCompany.com 05/04/11. Accessed 05/05/11. URL.

When I think about a gas mask, for some reason my mind flits to a memory of a series of drawings by British sculptor Henry Moore, which I encountered at the Hirshorn while wandering through the Smithsonian one afternoon during college. The London Underground functioned as a shelter during WWII, and Moore made a series of dark gray moody drawings that convey his experiences sleeping in the tunnels along with thousands of other Londoners at the height of the Blitz.  I’m not really sure if any of the drawings actually depicted people wearing gas masks, but that feeling of darkness and suffocation seems like it might be the common thread.

Image courtesy www.tate.org.uk

You may be asking yourself why on earth a person would be thinking about gas masks on a rainy morning while conducting materials research; let me assure you it’s not because somebody forgot to take out the garbage last night (but seriously, how hard is it to take out the trash!?)

Image courtesy thesurvivalzone.com

Gas masks and respirators, worn by emergency response teams and others who require protection from harmful vapors, contain carbon filters (activated charcoal), which traps the toxins before they can enter the lungs. The problem is that once the carbon filter saturates, it allows harmful chemicals to fly on through the canister without so much as a by-your-leave. Emergency workers currently rely on safety protocols that describe the length of time a gas mask can be worn without changing the mask, but there are too many variables to be completely certain that the charcoal filters are working.

In response to this problem, researchers at the University of California, San Diego working with Tyco Electronics have created a new kind of sensor from carbon nanostructures that could be used to warn emergency workers when the filters in their respirators have become saturated and no longer offer adequate protection. The new microsensors can provide a more accurate reading of how much material has been absorbed by the carbon in the filters (R&D Magazine). 

The researchers “assembled the nanofibers into repeating structures called photonic crystals that reflect specific wavelengths, or colors, of light. The wing scales of the Morpho butterfly, which give the insect its brilliant iridescent coloration, are natural examples of this kind of structure.  The sensors are an iridescent color too, rather than black like ordinary carbon. That color changes when the fibers absorb toxins – a visible indication of their capacity for absorbing additional chemicals” (Brown). You can learn more about the nanoscale structures that make up butterfly wings here.

Image: Timothy Kelly, UCSD Chemistry and Biochemistry

 Image: Brian King, UCSD Chemistry and Biochemistry

The UCSD team fabricated nanotubes that are less than half the width of a human hair.  The photonic sensors can be placed on the tips of optical fibers less than a millimeter across, and can be inserted into respirator cartridges.  According to the researchers, the crystals are sensitive enough to detect chemicals such as toluene at concentrations as low as one part per million (R&D Magazine).

I think these sensors have a wider applicability than just gas masks, however.  Green Building certification systems such as LEED or Green Globes give points for “flushing” a building after construction but prior to handing it over to occupants in order to lower the concentration of volatile organic compounds being emitted by things like paint, adhesives, carpet, plastics, etc. Imagine if you could tell by looking at the color of a sensor whether a building is safe to inhabit from a VOC standpoint?

WU XING:

Filed under fire and wood – because of the carbon and the charcoal.

Cited:

Brown, Susan. “New Material Could Improve Safety for First Responders to Emergencies.” UC San Diego News Center. 04/29/11. Accessed 05/02/11. URL.

R&D Magazine. “New Material Could Improve Safety for First Responders to Chemical Hazards.” 05/02/11. Accessed 05/02/11. URL.

Scientists have been working with carbon nanotubes (essentially, rolled up sheets of graphene) to encourage solar cells to convert more of the sun’s energy to electricity.  Theoretically, nanotubes “gather more electrons that are kicked up from the surface of a PV cell, allowing a greater number of electrons to produce a current” (Boyle).  More electrons means more power, so it’s a decent line of research to pursue.

image courtesy roselawgroup.com

In practice, however, using carbon nanotubes in solar cells has proved more complicated than one might like for two reasons: “first, the making of carbon nanotubes generally produces a mix of two types, some of which act as semiconductors (sometimes allowing an electric current to flow, sometimes not) or metals (which act like wires, allowing current to flow easily). The new research, for the first time, showed that the effects of these two types tend to be different, because the semiconducting nanotubes can enhance the performance of solar cells, but the metallic ones have the opposite effect. Second, nanotubes tend to clump together, which reduces their effectiveness” (Chandler). Understanding the differences between the two types of nanotubes could be useful for designing more efficient nanoscale batteries, piezoelectrics or other power-related materials.

Image credit Matt Klug, Biomolecular Materials Group

Graduate students Xiangnan Dang and Hyunjung Yi, MIT professor Angela Belcher and colleagues turned to biology for a solution to these nanochallenges, employing a genetically engineered version of a virus called M13, prone to attacking and infecting bacteria.  M13 can arrange and order nanotubes on a surface.  The virus has peptides that bind to the nanotubes, allowing them to separate the tubes so they can’t short out the circuits, and it also prevents clumping. “Each virus can grip about five to 10 nanotubes each, using roughly 300 of the protein molecules. The viruses were also genetically engineered to produce a layer of titanium dioxide, which happens to be the key ingredient in Grätzel cells, a.k.a. dye-sensitized solar cells… This close contact between TiO2 nanoparticles helps transport the electrons more efficiently” (Boyle).

Interestingly, the viruses also make the nanotubes water-soluble, which could lower manufacturing costs by facilitating the incorporation of nanotubes into solar cells at room temperature.  The virus-built structures enhanced the solar cells’ power conversion efficiency to 10.6 percent from 8 percent. That’s about a one-third improvement, using a viral system that makes up just 0.1 percent of the cells’ weight (Boyle). A little help from biology goes a long way.

WU XING:

I have filed this under fire, because the main idea relates to energy.

Cited:

Boyle, Rebecca. “MIT Researchers use Viruses to Build More Efficient Solar Panels.” Popsci.com 04/25/11. Accessed 04/26/11. URL.

Chandler, David L. “Solar Power Goes Viral.” MIT News Office. 04/25/11. Accessed 04/26/11. URL.