Powdered Glue Activates when Squished

Sometimes a hack needs something more than duct tape. Cyanoacrylate glue is great, if you don’t mind sticking your fingers together. But it doesn’t stick to everything, nor does it fill gaps. Epoxy is strong, but isn’t nearly as convenient. The point is, one type of glue doesn’t fit every situation, and that’s why you have to keep a lot of options.  [Syuji Fujii] of Japan’s Osaka Institute of Technology (and his colleagues) have a new option: a glue that goes on dry and sticks when squished.

According to New Scientist,  the researchers rolled spheres of a latex liquid in a layer of calcium-carbonate nanoparticles. The resulting spheres are a few millimeters across and pour easily. When put under pressure for a few seconds, the nanoparticles are pushed inside, and the sticky liquid contacts the surface. The source paper is also available if you want to read the gory details. Or you can cut right to the video below to see it in action.

If you don’t think glue is a good hacking material, you don’t know [Kevin Dady]. You can even glue wires if you really hate soldering, although we’d rather solder.

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Better Capacitors Through Nanotechnology

Traditionally, capacitors are like really bad rechargeable batteries. Supercapacitors changed that, making it practical to use a fast-charging capacitor in place of rechargeable batteries. However, supercapacitors work in a different way than conventional (dielectric) capacitors. They use either an electrostatic scheme to achieve very close separation of charge (as little as 0.3 nanometers) or electrochemical pseudocapacitance (or sometime a combination of those methods).

In a conventional capacitor the two electrodes are as close together as practical and as large as practical because the capacitance goes up with surface area and down with distance between the plates. Unfortunately, for high-performance energy storage, capacitors (of the conventional kind) have a problem: you can get high capacitance or high breakdown voltage, but not both. That’s intuitive since getting the plates closer makes for higher capacitance but also makes the dielectric more likely to break down as the electric field inside the capacitor becomes higher with both voltage and closer plate spacing (the electric field, E, is equal to the voltage divided by the plate spacing).

[Guowen Meng] and others from several Chinese and US universities recently published a paper in the journal Science Advances that offers a way around this problem. By using a 3D carbon nanotube electrode, they can improve a dielectric capacitor to perform nearly as well as a supercapacitor (they are claiming 2Wh/kg energy density in their device).

cap1The capacitor forms in a nanoporous membrane of anodic aluminum oxide. The pores do not go all the way through, but stop short, forming a barrier layer at the bottom of each pore. Some of the pores go through the material in one direction, and the rest go through in the other direction. The researchers deposited nanotubes in the pores and these tubes form the plates of the capacitor (see picture, right). The result is a capacitor with a high-capacity (due to the large surface area) but with an enhanced breakdown voltage thanks to the uniform pore walls.

cap2To improve performance, the pores in the aluminum oxide are formed so that one large pore pointing in one direction is surrounded by six smaller pores going in the other direction (see picture to left). In this configuration, the capacitance in a 1 micron thick membrane could be as high as 9.8 microfarads per square centimeter.

For comparison, most high-value conventional capacitors are electrolytic and use two different plates: a plate of metallic foil and a semi-liquid electrolyte.  You can even make one of these at home, if you are so inclined (see video below).

We’ve talked about supercapacitors before (even homebrew ones), and this technology could make high capacitance devices even better. We’ve also talked about graphene supercaps you can build yourself with a DVD burner.

It is amazing to think how a new technology like carbon nanotubes can make something as old and simple as a capacitor better. You have to wonder what other improvements will come as we understand these new materials even better.

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Rod Logic and Graphene: Elusive Molecule-Scale Computers

I collect slide rules. You probably know a slide rule is a mechanical calculator of sorts. They usually look like a ruler (hence the name) and have a sliding part (hence the name) and by using logarithms you can multiply and divide easily by doing number line addition and subtraction (among other things).

It is easy to dismiss old technology like that out of hand as being antiquated, but mechanical computing may be making a comeback. It may seem ancient, but mechanical adding machines, cash registers, and even weapon control computers were all mechanical devices a few decades ago and there were some pretty sophisticated techniques developed to make them work. Perhaps the most sophisticated of all was Babbage’s difference engine, even though he didn’t have the technology to make one that actually functioned (the Computer History Museum did though; you should see it operating in person, but this is good too).

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Optical Rectenna Converts Light to DC

Using multiwall carbon nanotubes, researchers at Georgia Institute of Technology have created what they say are the first optical rectennas–antennas with rectifiers that produce DC current. The work could lead to new technology for advanced photodetectors, new ways to convert waste heat to electricity and, possibly, more efficient ways to capture solar energy.

A paper in Nature Nanotechnology describes how light striking the nanotube antennas create a charge that moves through attached rectifiers. Challenges included making the antennas small enough for optical wavelengths, and creating  diodes small enough and fast enough to work at the extremely short wavelengths. The rectifiers switch on and off at petahertz speeds (something the Institute says is a record).  Continue reading “Optical Rectenna Converts Light to DC”

Check it out, my clothes are electric. No, seriously

Someday you may be able to use your crotch or armpits to recharge that cellphone. Heck, maybe there won’t even be a battery, just a capacitor which gets its juice from Power Felt, a fabric that converts body heat to electricity.

Now we mention the nether-regions because it’s funny, but also because it makes the most sense. Researchers have developed a fabric containing carbon nanotubes used in a way that generates electricity based on a temperature differential. We figure the areas on the body that have high heat loss would be the most efficient locations for the fabric since it is currently extremely expensive to produce (the hope is that mass-production would reduce cost by orders of magnitude). So we think battery-charging briefs are a definite possibility.

What we see here is a nano-scale Peltier electricity generator. It’s the same concept as this candle-based generator, except the increased efficiency of the Power Felt lets your wasted body heat take the place of the flame.

There’s a white paper on the topic but you can’t get at it without surrendering some [George Washingtons].

[via Reddit and Megadgets]

Tapping Tree Power

[bugloaf] tipped us off about this flower power hack. University of Washington researchers, [Babak], [Brian], and [Carlton] have developed very low power circuits to run directly off of trees. This builds upon the work of MIT researchers and Voltree Power. A voltage of up to around 200mV is generated between an electrode in a tree and an electrode in the ground. Identical metals can be used as electrodes as the process is not like that of a lemon or potato battery. The significant development here is the use of a boost converter and exceptionally low power circuits. What kind of applications can you come up with for this source of power? Maybe you could try to combine this power with the power from donuts and hair.

Science fiction, help or hindrance?

[Annalee Newitz] from io9 has written a piece about how science fiction can impact the public’s perception of scientific research. She’s covered stories ranging from Frankenstein, for showing the negatives of humans “playing god”, to The Diamond Age, for showing an inspiring use of nanotechnology.

We wonder what direct impact science fiction has had on research. Depictions of a 3D metaverse have always been compelling, but is pouring effort into half measures like Second Life a waste of time compared to serious computer interaction research?

We discussed this for a little while and concluded that whether inspiring or hindering, the very act of critically thinking about technology was beneficial. What books have inspired you in the past? Was it because they showed a better world or were they a stern warning?