Posts Tagged ‘electrodes’
A Transparent Battery to Power Next-Gen See-Through Gadgets
There are a few ways to make an electronic component transparent. One is to make it so thin that it doesn’t register with the human eye. Or you can make the component take the form of a pattern whose features are so small they are invisible. Some battery components are easy to render transparent by shrinking them, but electrodes are particularly difficult to make thin. A super-thin electrode isn’t energy dense, and therefore it doesn’t store up enough power to be useful in any realistic way.
So Cui opted for the second approach. He and his team figured that if you can pattern the electrode into a superfine mesh, you can still build an energy dense battery. With enough electrode material distributed across the mesh, a battery can still hold a significant charge.
So using a relatively straightforward lithography method, they built a framework for the mesh in a soft, clear, spongy material called PDMS. To make a complete battery, they simply need two of these layers filled with electrode material--in this case, they used the makings of a standard lithium-ion battery--with a gel electrolyte (also clear, of course) sandwiched in between. Encase the whole thing in plastic, and you’ve got a see-through battery.
In the lab, the batteries have been used to power a small LED light (which can be viewed straight through the battery itself). Cui thinks the batteries should be roughly half as energy dense as a equally-sized regular battery. So right now the prototype is about as powerful as a NiCad battery, but Cui says he and his team should be able to improve that by an order of magnitude by reducing inefficiencies in the prototype design and layering batteries one atop the other. Depending on how it scales, the Stanford team thinks such transparent batteries could be commercialized in just two to four years.
See a video of the technology in practice via the Tech Review link below.
[]
Video: Powerful Magnets Pointed At British Editor’s Head Prevent Him From Reciting A Nursery Rhyme
Magnetic fields applied to the brain can be used to , and even and sense of morality. But unless you’re a neuroscientist, it’s hard to see the physiology of this phenomenon, other than trying to interpret colorful brain scans.
The following video accomplishes this beautifully. And not just because it cuts off a science editor’s ability to speak.
Watch below as New Scientist editor of "Humpty Dumpty" is interrupted by magnetic interference. Vincent Walsh from the Institute of Cognitive Neuroscience at University College London used magnets to shut off Highfield’s speech center, the British science mag reports.
Transcranial magnetic stimulation, as this is called, is a useful way to inhibit specific regions of the brain. Along with boosting visual memory, it can make you , for instance. It’s even been shown to ; DARPA is studying the technique for , allowing soldiers to manipulate brain functions to boost alertness, relieve stress or reduce the effects of traumatic brain injury.
Walsh and colleagues are studying the use of the technique to treat migraine and stroke, New Scientist says.
At publication time, PopSci editors were as yet unwilling to duplicate the experiment.
[]
In The Tiniest Receiver Ever, Graphene Can Directly Detect Radio Signals
Stretched between two electrodes and hovering over a third, the graphene sheet works like a trampoline, resonating in response to a voltage that changes with radio frequency signals. The effect can be monitored by measuring the capacitance between the sheet and the third electrode.
This is a major advance, according to — most nano resonators suffer from parasitic capacitance, a natural problem when small circuit parts are squished close together. This interference drowns out the actual radio signals, and fixing it requires downmixing the signals, which limits the radio’s bandwidth and makes it less effective. But Yuehang Xu and colleagues at Columbia University say their graphene sheet radio has a special gate design that cancels out the parasitic effect.
The technique is two orders of magnitude faster than the typical radio signal mixing method. The researchers were able to read out a radio signal of 33.27 MHz, but they say a smaller, improved device could reach the GHz range.
The biggest drawback: the nano radio works at -321° F, so it will need some tweaks before it can be used in communications devices.
[]
Squishy Bio-Electronics Could Make Better Implants and Brain-Machine Interface Controls
A pair of grad students at North Carolina State University presented a paper last week describing a quasi-liquid diode whose electrodes are made of a gallium-indium alloy that is liquid at room temperature. Two hydrogel films are sandwiched between the electrodes — one is doped with an acid and the other holds an alkaline compound.
The interface between the electrodes develops a thin coating of gallium oxide, which creates resistance, as explains. The electrode with the alkaline substance suppresses the formation of this skin. So, applying voltage changes the the thickness of this gallium oxide “skin” — negative voltage makes the oxide thinner, lowering the device’s resistance, and a positive voltage makes it thicker, producing greater resistance.
What’s more, the device retains a memory of its resistance state even after it is turned of, so it acts like a memristor, according to Ju-Hee So, a chemistry grad student who presented a paper on the device last week at the fall meeting of the Materials Research Society in Boston.
The same research lab has previously worked with gallium-indium alloys to build ; it can bend and stretch but return to its original shape without breaking. This could make it more useful for future implants like artificial limbs — they would be less rigid and would not need to be isolated from the body's inherent moisture.
So told IEEE Spectrum she believes the alloys in this device would be compatible with human tissue. Eventually, they could be used to build bioelectronic circuits between living tissue and computers, like brain-machine interfaces that would control artificial limbs or artificial neural networks.
[]
DARPA’s Future Li-ion Batteries Will Be Smaller Than Grains of Salt
Jane Chang, an engineer at the University of California-Los Angeles, is designing a tiny solid electrolyte that allows charge to flow between two nanoscale electrodes. Eventually, the wee batteries could be used to power a host of micro and nanodevices.
The special electrolyte is basically just a series of nanowires coated with conductive material. Chang is using painstakingly slow atomic layer deposition to spray minuscule amounts of lithium aluminosilicate onto the nanowires. The solid compound allows current to flow within a battery. The nanowires are designed to have a high surface-to-volume ratio, making them more efficient.
“We're trying to achieve the same power densities, the same energy densities, as traditional lithium ion batteries, but we need to make the footprint much smaller,” Chang says.
Nanoscale electrodes are being designed in other labs, but so far, no one has built a complete working nano-battery, according to UCLA.
If they work, they could be more effective, and perhaps less prone to scary malfunction, than or . The batteries could be useful for powering devices for medical diagnostics and treatment, among other technologies.
Chang announced her latest results Tuesday at the AVS 57th International Symposium & Exhibition in Albuquerque.
Electrically Stimulating the Brain Can Boost Visual Memory 110 Percent
The finding is a follow-up to previous research at the same lab that shows certain types of brain stimulation can unlock savant qualities in people who had not previously exhibited them.
Richard Chi, a Ph.D. student at the Centre for the Mind at the University of Sydney, wondered if inhibiting a specific brain area could improve memory as well as perceptual skills experienced by people with autism, reports.
In the study, 36 volunteers examined a series of slides containing shapes that varied in number, size and color, according to New Scientist. Then they were shown five "test" slides, some of which included the study slides, and some that did not. They were asked if they could remember any of the original "study" slides.
Then they donned an electrode cap that transmitted a weak electrical signal, in a method called transcranial direct current stimulation. One group received signals that boosted their right anterior temporal lobes, and suppressed activity on their left ATL. A second group got the opposite treatment and a third was a placebo group.
The first group's shape-recognition scores improved by 110 percent, the study found.
Both sides of the anterior temporal lobe are important for memory processing -- the left ATL deals with context, while the right ATL is associated with visual memory, New Scientist says. Chi's team says inhibiting activity in the left ATL reduces the confusing influence of context, cutting down on visual memory errors. People can more easily perceive the literal details of what they're seeing.
The team has already shown that low-frequency magnetic pulses can , also by temporarily inhibiting the left ATL.
People with autism have lesions on their left ATL, New Scientist reports.
[]
It’s a Trap! Atom Corral Is a Major Step Toward Quantum Computing
Whereas computers now use transistors to crunch 0s and 1s, a quantum computer could theoretically perform dozens of calculations simultaneously by zapping charged subatomic particles, called ions, with a laser.
One of the first steps in building a functional quantum computer is trapping the ions in order to zap them. That’s why physicists at the National Institute of Standards and Technology have created this ion trap, a web of electrodes that produces an electric field to hold the ions in place. Once in place, the ions hover just above the trap’s surface. Project physicist Jason Amini says there’s still much work to do. For example, he and his group would like to build a trap that can hold hundreds of ions instead of the two or three it currently manages. If they can pull it off, the traps could outperform conventional computers on certain tasks within the next five years.