graphene

41 Articles

Carbon Augmented Spider Silk

March 15, 2018 by 22 Comments

Some of the creepy-crawlers under our feet, flitting through the air, and waiting on silk webs, incorporate metals into their rigid body parts and make themselves harder. Like Mega Man, they absorb the metals to improve themselves. In addition to making their bodies harder, silk-producing creatures like worms and spiders can spin webs with augmented properties. These silks can be conductive, insulating, or stronger depending on the doping elements.

At Italy’s University of Trento, they are pushing the limits and dosing spiders with single-wall carbon nanotubes and graphene. The carbon is suspended in water and sprayed into the spider’s habitat. After the treatment, the silk is measured, and in some cases, the silk is significantly tougher and surpasses all the naturally occurring fibers.

Commercial spider silk harvesting hasn’t been successful, so maybe the next billionaire is reading this right now. Let’s not make aircraft-grade aluminum mosquitoes though. In fact, here’s a simple hack to ground mosquitoes permanently. If you prefer your insects alive, maybe you also like their sound.

Thank you for the tip, [gippgig].

DIY Graphene Putty Makes Super Sensitive Sensor

January 23, 2018 by 34 Comments

It is sort of an electronics rule 34 that if something occurs, someone needs to sense it. [Bblorgggg], for reasons that aren’t immediately obvious, needs to sense ants moving over trees. No kidding. How are you going to do that? His answer was to use graphene.

Actually, his super sensitive sensors mix graphene in Silly Putty, an unlikely combination that he tried after reading (on Hackaday, no less) about similar experiments at Trinity College resulting in Gputty. The Gputty was highly sensitive to pressure, and so it appears is his DIY version called Goophene. At Trinity they claimed to be able to record the footsteps of a spider, so detecting ant stomping didn’t seem too far-fetched. You can see a video of the result, below.

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Graphene Biosensors Are Extra Quiet

October 31, 2017 by 9 Comments

Graphene has attracted enormous interest for electrically detecting chemical and biological materials. However, because the super material doesn’t act like a normal semiconductor, transistors require multiple layers of the material, and that’s bad for 1/f noise especially when the transistors operate at maximum transconductance. Researchers have found a way to operate graphene transistors at a neutral point, significantly reducing 1/f noise while not impacting the sensor’s response.

The team created a proof-of concept sensor that could detect an HIV-related DNA hybridization. The sensor was able to detect very tiny concentrations of the material.

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Graphene From Graphite By Electrochemical Exfoliation

June 17, 2017 by 9 Comments

Graphene is an interesting material, but making enough of the stuff to do something useful can be a little tough. That’s why we’re always on the lookout for new methods, like this electrochemical process for producing graphene in bulk.

You probably know that graphene is a molecular monolayer of carbon atoms linked in hexagonal arrays. Getting to that monolayer is a difficult proposition, but useful bits of graphene can be created by various mechanical and chemical treatments of common graphite. [The Thought Emporium]’s approach to harvesting graphene from graphite is a two-step process starting with electrochemical exfoliation. Strips of thin graphite foil are electrolyzed in a bath of ferrous sulfate, resulting in the graphite delaminating and flaking off into the electrolyte. After filtering and cleaning, the almost graphene is further exfoliated in an ultrasonic cleaner. The result is gram quantity yields with very little work and at low cost.

There’s plenty of effort going into new methods of creating graphene these days, whether by barely controlled explosions or superheating soybean oil. But will graphene be the Next Big Thing? The jury is still out on that.

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Solar-Powered Prosthetic Skin

April 1, 2017 by 3 Comments

One of the biggest problems for prosthetic users is feel. If you’ve ever tried to hold a pen and write with a numb hand, you’ve realised how important feedback is to the motor control equation. Research is ongoing to find ways to provide feedback from prosthetic limbs, in even a basic format.  The human nervous system is a little more complex than just interfacing with the average serial UART. One of the requirements of many feedback systems is power, which usually would involve bulky batteries or some form of supercapacitors, but a British team has developed a way to embed solar cells in a touch-sensitive prosthetic skin.

The skin relies on everyone’s favourite material of the minute, graphene. A thin layer of graphene allows the prosthetic to feed signals back to the user of both temperature and contact pressure. The trick is that the graphene skin is incredibly transparent, reportedly allowing 98% of light on its surface to pass through. It’s then a simple matter of fitting solar panels beneath this skin, and the energy harvested can then be used to power the sensor system.

The team does admit that some power storage will later be required, as it would be difficult for any prosthetic user if their limbs lost all feedback when they walked into a dark room. The idea of one’s arm losing all feeling upon going to bed isn’t particularly appealing. Check out the paper here (paywalled). Video below the break.
We see a lot of great prosthetic projects cross our desk here at Hackaday – like this 3D printed prosthetic hand. Prosthetics definitely matter, so why not build your own and enter it in the 2017 Hackaday Prize?

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Explosive New Process Produces Graphene By The Gram

February 14, 2017 by 45 Comments

You say you need some graphene so you can invent the Next Big Thing, but you can’t be bothered with processes that yield a few measly milligrams of the precious stuff. Luckily for you there’s a new method for producing gram quantities of graphene. Perhaps unluckily, it requires building a controlled fuel-air bomb.

Graphene is all the rage today, promising to revolutionize everything from batteries to supercapacitors to semiconductors. A molecularly-2D surface with unique properties, graphene can be made in very small quantities with such tedious methods as pulling flakes of the stuff off graphite lumps with Scotch tape. Slightly less ad hoc methods involve lasers, microwaves, or high temperatures and nasty chemicals. But all of these methods are batch methods that produce vanishingly small amounts of the stuff.

The method [Chris Sorenson] et al of Kansas State University developed, which involves detonating acetylene and oxygen in a sturdy pressure vessel with a spark plug, can produce grams of graphene at a go. And what’s more, as their patent application makes clear, the method is amenable to a continuous production process using essentially an acetylene-fueled internal combustion engine.

While we can’t encourage our readers to build an acetylene bomb in the garage, the process is so simple that it would be easily replicated. We wonder how far down it could scale for safety and still produce graphene. Obviously, be careful if you choose to replicate this experiment. If you don’t like explosions and can source some soybean oil and nickel foil, maybe try this method instead. Then you’ll have something to mix with your Silly Putty.

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Flexible, Sensitive Sensors From Silly Putty And Graphene

December 18, 2016 by 16 Comments

Everyone’s favorite viscoelastic non-Newtonian fluid has a new use, besides bouncing, stretching, and getting caught in your kid’s hair. Yes, it’s Silly Putty, and when mixed with graphene it turns out to make a dandy force sensor.

To be clear, [Jonathan Coleman] and his colleagues at Trinity College in Dublin aren’t buying the familiar plastic eggs from the local toy store for their experiments. They’re making they’re own silicone polymers, but their methods (listed in this paywalled article from the journal Science) are actually easy to replicate. They just mix silicone oil, or polydimethylsiloxane (PDMS), with boric acid, and apply a little heat. The boron compound cross-links the PDMS and makes a substance very similar to the bouncy putty. The lab also synthesizes its own graphene by sonicating graphite in a solvent and isolating the graphene with centrifugation and filtration; that might be a little hard for the home gamer to accomplish, but we’ve covered a DIY synthesis before, so it should be possible.

With the raw materials in hand, it’s a simple matter of mixing and kneading, and you’ve got a flexible, stretchable sensor. [Coleman] et al report using sensors fashioned from the mixture to detect the pulse in the carotid artery and even watch the footsteps of a spider. It looks like fun stuff to play with, and we can see tons of applications for flexible, inert strain sensors like these.

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