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Friday, 19 September 2014

This nuclear battery could power your smartphone forever.....

Your next smartphone or electric vehicle might be powered by a nuclear battery instead of your usual lithium-ion cell thanks to a breakthrough made by University of Missouri researchers. This is bad news for those of you who think that WiFi signals are bad for your health — especially if they’re received by a smartphone situated near your head or gonads — but great news for all of the people who value all-day battery life ahead of increased radiation exposure. The world could probably do with reduced fertility rates anyway, right?
First, just to put your mind at rest: This nuclear battery doesn’t contain a mini nuclear fission reactor — that would be insane (at least given our current grasp of nuclear power generation, anyway). Instead, this battery, developed by Baek Kim and Jae Kwon at the University of Missouri, uses the betavoltaic process to generate electricity. A betavoltaic device, as the name implies, is fairly similar a photovoltaic device — but instead of generating electricity from photons, it generates electricity from beta radiation — i.e. high-energy electrons that are emitted by radioactive elements. A betavoltaic device is constructed in almost exactly the same way as a photovoltaic cell: a piece of silicon (or other semiconductor) is wedged between two electrodes, and when radiation hits the semiconductor it produces a flow of electrons (voltage, electricity).
“But surely having a battery, and thus a mobile device, packed full of radioactive material is a bad idea” I hear you say. And usually, yes, you’d be right. What makes a betavoltaic battery somewhat safe is that beta radiation can be easily stopped with a thin piece of aluminium; gamma radiation, on the other hand, has so much penetrative power that it can only be stopped by a big lump of lead (or other dense metal). This doesn’t mean that beta radiation in itself is safe — it can cause cancer and death — but it’s much easier to control. Just make sure the betavoltaic nuclear battery casing is more than a couple of millimeters thick — and don’t drop it. Ever.

Anyway, back to the University of Missouri’s battery. Basically, Kim and Kwon’s nuclear battery consists of a platinum-coated titanium dioxide electrode, water, and a piece of radioactive strontium-90. Strontium-90 (Sr-90) radioactively decays with a half-life of 28.79 years, producing an electron (beta radiation), an anti-neutrino, and the isotope yttrium-90. Y-90 itself has a half-life of just 64 hours, decaying into more electrons, anti-neutrinos, and zirconium (which is stable). The best thing about using strontium-90 as a fuel is that it produces almost no gamma radiation — so, as far as radioactive materials go, it’s pretty safe and easy to handle. (Still, there’s no avoiding the fact that it’s used extensively in medicine, both for radiotherapy of cancer, and as a radioactive tracer.)

While betavoltaic batteries are fairly old hat — they powered some of the earlier pacemakers, before more advanced chemistries such as lithium-ion arrived — the Missouri researchers say that their addition of water is a key breakthrough. Not only does water absorb a lot of the energy of the beta radiation (in high quantities it’s damaging to the betavoltaic semiconductor), but the beta radiation also splits the water molecules, producing free radicals and electricity.

“Water acts as a buffer and surface plasmons created in the device turned out to be very useful in increasing its efficiency,” Kwon says. “The ionic solution is not easily frozen at very low temperatures and could work in a wide variety of applications, including car batteries and, if packaged properly, perhaps spacecraft.” [Research paper: doi:10.1038/srep05249 - "Plasmon-assisted radiolytic energy conversion in aqueous solutions"]

Ultimately, even if beta radiation can be quite easily contained, I doubt we’ll ever see commercial nuclear batteries. Those headlines about exploding lithium-ion batteries are already scary enough; I can’t imagine Apple or Samsung will ever open themselves up to even worse headlines/lawsuits. (“Smartphone owner dies from acute radiation sickness after dropping his phone”.) There’s also the distinct possibility of terrorists creating a dirty bomb from all of that strontium-90 (which itself isn’t cheap, incidentally).
For now, nuclear batteries will probably only be used in military and space applications, where extreme longevity outweighs any risks. Still, it’s nice to dream of a smartphone or other mobile device that never once needs recharging…

Thursday, 4 September 2014

World-first experiment achieves direct brain-to-brain communication in human subjects

For the first time, an international team of neuroscientists has transmitted a message from the brain of one person in India to the brains of three people in France.

The team, which includes researchers from Harvard Medical School’s Beth Israel Deaconess Medical Center, the Starlab Barcelona in Spain, and Axilum Robotics in France, has announced today the successful transmission of a brain-to-brain message over a distance of 8,000 kilometres. 
"We wanted to find out if one could communicate directly between two people by reading out the brain activity from one person and injecting brain activity into the second person, and do so across great physical distances by leveraging existing communication pathways,” said one of the team, Harvard’s Alvaro Pascual-Leone in a press release. "One such pathway is, of course, the Internet, so our question became, 'Could we develop an experiment that would bypass the talking or typing part of internet and establish direct brain-to-brain communication between subjects located far away from each other in India and France?'"
The team achieved this world-first feat by fitting out one of their participants - known as the emitter - with a device called an electrode-based brain-computer (BCI). This device, which sits over the participant’s head, can interpret the electrical currents in the participant’s brain and translate them into a binary code called Bacon's cipher. This type of code is similar to what computers use, but more compact. 
"The emitter now has to enter that binary string into the laptop using her thoughts,” says Francie Diep at Popular Science. "She does this by using her thoughts to move the white circle on-screen to different corners of the screen. (Upper right corner for "1," bottom right corner for "0.") This part of the process takes advantage of technology that several labs have developed, to allow people with paralysis to control computer cursors or robot arms."
Once uploaded, this code is then transmitted via the Internet to another participant - called the receiver - who was also fitted with a device, this time a computer-brain interface (CBI). This device emits electrical pulses, directed by a robotic arm, through the receiver’s head, which make them ‘see’ flashes of light calledphosphenes that don’t actually exist. 
"As soon as the receivers' machine gets the emitter's binary message over the Internet, the machine gets to work,” says Diep. "It moves its robotic arm around, sending phosphenes to the receivers at different positions on their skulls. Flashes appearing in one position correspond to 1s in the emitter's message, while flashes appearing in another position correspond to 0s.
Exactly how the receivers are recording the flashes so they can translate all those 0s and 1s isn’t clear, but it could be as simple and writing them down with an actual pen and paper.
While it’s not clear at this stage what the applications for this technology could be, it’s a pretty incredible achievement. Oh, and the messages they transmitted? The conveniently brief and friendly, “Hola” and “Ciao”. 
The team published its research in the journalPLOS One

Scientists engineer bacteria to produce renewable, engine-ready propane gas

Researchers have successfully engineered E. coli to generate renewable, engine-ready propane, which is a major sustainable fossil fuel replacement candidate.

Propane has huge potential as a replacement for our rapidly dwindling fossil fuels because we already have a market for it - it's one of the main components in LPG (liquid petroleum gas), which we use in vehicles and heating. But right now it’s only produced as a byproduct of natural gas processing and petroleum refining, both of which are very unsustainable practices.
Now researchers from the Imperial College London in the UK and the University of Turku in Finland have proved that propane can be produced sustainably, by showing that the harmless gut bacteria Escherichia coli (E. coli) can be engineered to make renewable propane.
To turn the bacteria into propane-producing machines, the scientists interrupted the biological process that turns fatty acids into cell membranes. The researchers used three novel enzymes to channel the fatty acids along a different biological pathway, resulting in the bacteria producing engine-ready, renewable propane instead of cell membranes. The results are published in Nature Communications.
Their goal is now to insert this engineered production line into photosynthetic bacteria, which harvest energy from the sun, so that one day they’ll be able to directly convert solar energy into chemical fuel. The E. coli in this experiment were powered by sugar. The scientists also need to scale up the process - right now they’re producing 1,000 times less propane from the reaction then they would need to make the process commercially viable.
"Although this research is at a very early stage, our proof of concept study provides a method for renewable production of a fuel that previously was only accessible from fossil reserves,” said Patrik Jones, a synthetic biologist and one of the authors of the paper from the Imperial College London, in a press release.
“Although we have only produced tiny amounts so far, the fuel we have produced is ready to be used in an engine straight away. This opens up possibilities for future sustainable production of renewable fuels that at first could complement, and thereafter replace fossil fuels like diesel, petrol, natural gas and jet fuel.”
The researchers chose to make the E. coliproduce propane as opposed to gasoline or other fossil fuels, because propane can easily be converted from a liquid to a gas. The bacteria cells produce propane gas, but then the researchers can cheaply and easily transform this into a liquid that can be stored and transported.
"Fossil fuels are a finite resource and as our population continues to grow we are going to have to come up with new ways to meet increasing energy demands. It is a substantial challenge, however, to develop a renewable process that is low-cost and economically sustainable. At the moment algae can be used to make biodiesel, but it is not commercially viable as harvesting and processing requires a lot of energy and money. So we chose propane because it can be separated from the natural process with minimal energy and it will be compatible with the existing infrastructure for easy use,” said Jones.
The scientists are now trying to better understand what’s going on behind the scenes of the production process to make the process more efficient. "I hope that over the next 5-10 years we will be able to achieve commercially viable processes that will sustainably fuel our energy demands,” said Jones.

Monday, 4 August 2014

MEMS Piezoelectric GYROSCOPE

Tracking the position of an object is an important engineering problem that finds many application areas including military, industrial, medical, and consumer applications. This problem is effectively solved with gyroscopes, and these sensors find the orientation and angular velocity Knowing linear acceleration and angular velocity in three dimensions is enough to track the motion of the system with the help of additional mathematical operations. solved with gyroscopes, and these sensors find the orientation and angular velocity Knowing linear acceleration and angular velocity in three dimensions is enough to track the motion of the system with the help of additional mathematical operations. MEMS piezoelectric gyroscope is an inertial sensing integrated circuit that measures the angle and rate of rotation in an object or system. Programmable for targeted applications, this technology relies on three dimensional axes of sensing, which are X (pitch), Y (roll), and Z (yaw). In this paper, we have reported the design and simulation of MEMS piezoelectric gyroscope by COMSOL Multiphysics.

Saturday, 26 July 2014

'Optical fibre' made out of thin air.

Lasers were used to create a column of low-density air surrounding a core of higher-density air that acted like a conduit to channel light (USAF)
Scientists say they have turned thin air into an 'optical fibre' that can transmit and amplify light signals without the need for any cables.
In a proof-of-principle experiment they created an "air waveguide" that could one day be used as an instantaneous optical fibre to any point on earth, or even into space.
The findings, reported in the journal Optica, have applications in long range laser communications, high-resolution topographic mapping, air pollution and climate change research, and could also be used by the military to make laser weapons.
"People have been thinking about making air waveguides for a while, but this is the first time it's been realised," says Professor Howard Milchberg of the University of Maryland, who led the research, which was funded by the US military and National Science Foundation.
Lasers lose intensity and focus with increasing distance as photons naturally spread apart and interact with atoms and molecules in the air.
Fibre optics solves this problem by beaming the light through glass cores with a high refractive index, which is good for transmitting light.
The core is surrounded by material with a lower refractive index that reflects light back in to the core, preventing the beam from losing focus or intensity.
Fibre optics, however, are limited in the amount of power they can carry and the need for a physical structure to support them.

Light and air

Milchberg and colleagues' made the equivalent of an optical fibre out of thin air by generating a laser with its light split into a ring of multiple beams forming a pipe.
They used very short and powerful pulses from the laser to heat the air molecules along the beam extremely quickly.
Such rapid heating produced sound waves that took about a microsecond to converge to the centre of the pipe, creating a high-density area surrounded by a low-density area left behind in the wake of the laser beams.
"A microsecond is a long time compared to how far light propagates, so the light is gone and a microsecond later those sound waves collide in the centre, enhancing the air density there," says Milchberg.
The lower density region of air surrounding the centre of the air waveguide had a lower refractive index, keeping the light focused.
"Any structure [even air] which has a higher density will have a higher index of refraction and thereby act like an optical fibre," says Milchberg.

Amplified signal

Once Milchberg and colleagues created their air waveguide, they used a second laser to spark the air at one end of the waveguide turning it into plasma.
An optical signal from the spark was transmitted along the air waveguide, over a distance of a metre to a detector at the other end.
The signal collected by the detector was strong enough to allow Milchberg and colleagues to analyse the chemical composition of the air that produced the spark.
The researchers found the signal was 50 per cent stronger than a signal obtained without an air waveguide.
The findings show the air waveguide can be used as a "remote collection optic," says Milchberg.
"This is an optical fibre cable that you can reel out at the speed of light and place next to [something] that you want to measure remotely, and have the signal come all the way back to where you are."
Australian expert Professor Ben Eggleton of the University of Sydney says this is potentially an important advance for the field of optics.
"It's sort of like you have an optical fibre that you can shine into the sky, connecting your laser to the top of the atmosphere," says Eggleton.
"You don't need big lenses and optics, it's already guided along this channel in the atmosphere."