- Micromachine power problem solved with magnets
- Single-Molecule Magnets Open New Door for Information Technology
- A water splitter with a double role
- Physicist develops battery using new source of energy
- Self-Organizing Nanotech Could Store 250 DVDs on One Coin-Size Surface
Micromachine power problem solved with magnets
- 17:25 02 March 2009 by Colin Barras
Now two new studies demonstrate what could be a solution: using magnetic fields to remotely power and control microscopic machines.
One of those machines is a micro-motor inspired by the corkscrewed spinning tail, or flagellum, which spins and swims like the real thing, and can propel a mass roughly the same size as real bacteria.
The artificial flagellum is driven by the changing magnetic field produced by three pairs of electromagnetic coils positioned to cover the X, Y and Z axes of 3D space, and positioned around the tank of water in which the machine moves. Its 47-micrometer-long helical tail is fashioned from a ribbon of a semiconductor material and it has a 4.5-micrometer-long magnetic "head" composed of chromium, nickel and gold.
By continually varying the electric current passing through each magnet pair, the team is able to generate a rotating magnetic field. The magnetic head constantly adjusts to align with the changing field, which causes the tail to spin and drives the machine forwards (see movie).
"The fastest [speed] we have achieved with the current setup is 20 micrometers per second [around four-tenths of a body length]," says Nelson. "But with some minor electronic modifications we expect over 100 micrometers per second."
Self-propelled devices like this could be useful in biomedicine, where they could manipulate sub-cellular objects, or help in targeted drug delivery, Nelson says. "
The studies of the team of Alexey Snezhko at the Argonne National Laboratory studies into magnetic manipulation at the microscopic scale have produced self-assembling magnetic "snakes" capable of ferrying a microscopic cargo across the surface of a liquid.
The snakes start off as individual 90-micrometer-wide nickel spheres floating on the surface of a beaker of water. Magnetic coils placed around the container causes these tiny balls to spin on the spot, generating small whirlpools that drive them across the surface. When two spheres pass sufficiently close to each other they join up due to magnetic attraction, eventually forming long snake-like strings.
The combined effect of the spinning particles in a snake generates stronger whirlpools that act rather like engines, but because the engines are all similar in size and working in opposite directions they cancel one another out and the snake remains motionless.
However, if an object - for example a polystyrene bead - obstructs one of those whirlpool engines then the snake is forced out of balance and is driven across the surface of the water by the others. It's a mechanism that has no analogy in nature, says Snezhko.
Tweaking the magnetic fields provides a way to move around small-scale cargo with precision. However, it is unlikely that the snakes could be used to deliver drugs inside the body because they only move on the surface of a liquid. They are likely to be more useful to mix chemicals and increase reaction rates, Snezhko says. They could also be used to clean up the surface of a water body, he suggests. source
My comment: Just imagine those little guys. I find them quite cool-they are so small, yet they could be very useful. Imagine how the little ones roam trough your body and clean it from all the junk you have gathered during the years. Nice!
Single-Molecule Magnets Open New Door for Information TechnologyMarch 9th, 2009 By Laura Mgrdichian
(PhysOrg.com) -- Recent research by scientists in Italy and France shows that that single molecules have the ability to store information via their magnetic state. Their work is a first step toward a new generation of ultra-compact data storage technologies based on individual molecules.
Using x-ray analysis methods, the group learned that iron-containing molecules can display a magnetic "memory" when tethered to a gold surface. This type of finding is a necessary precursor to the ability to store data, bit by bit, on individual molecules rather than capacitors or transistors, which are much larger.
Scientists have successfully organized molecules on conducting surfaces, but prior to this work had been unable to determine whether the molecules could retain a specific magnetic property: its ability to "remember" its magnetization history on the molecular level when demagnetized; this is known as magnetic hysteresis. Not only do small molecule clusters tend to be chemically unstable on surfaces, but scientists also lacked the tools to study them.
As they report in their paper, Sessoli and her colleagues proved that synchrotron radiation, the light emitted when charged particles are accelerated to nearly the speed of light around a large conducting ring, is the ideal tool for investigating these materials. Synchrotrons can produce all types of light, from radio waves to gamma-rays.
They used x-ray absorption spectroscopy (XAS), in which the x-ray photon energies are tuned to a range in which they can excite core electrons of the selected atomic species, in this case iron. While XAS can probe the electronic state of the deposited molecules, their magnetic properties can be investigated by magnetic circular dichroism (XMCD). It measures how a sample's response to x-ray light that is left circularly polarized (the rays rotate to the left as they propagate forward) is different from light that is right circularly polarized, when the sample is placed in a magnetic field. This method is best at telling researchers about the magnetic properties of the molecules, such as each molecule's "spin," an intrinsic property of a particle, atom, or molecule that imparts it with a very small magnetic field, like a tiny bar magnet. source
My comment: Now, this might be a far shot-individual synchrotron emission detector is hard to imagine right now, but if you think about it, your cdrom writer uses lasers and couple of decades ago, it was unthinkable to have that small lasers. But now we have them. So, imagine the new data storages-with data written in every molecule. Just imagine how much info you could store on a dvd, or on something not so wide, but thicker. Cool, huh?
A water splitter with a double roleMarch 9th, 2009 By Lucy Goodchild
(PhysOrg.com) -- There is a lot of hope invested in hydrogen, but it also presents some problems. It is energy-rich, clean and, as a constituent of water, of almost unlimited availability. However, so far it has been difficult to access it. Scientists at the Max Planck In-stitute of Colloids and Interfaces have now found a simple, low-cost way to produce hydrogen.
They extract this energy source from water by irradiating it with sunlight and using a carbon nitride as an inexpensive photo catalyst. Up to now this reaction has required organometal compounds and inorganic semiconductors combined with expensive precious metals, such as platinum.
Scientists at the Max Planck Institute of Colloids and Interfaces have used a carbon nitride, to create hydrogen from water with the aid of sunlight. "The special thing about carbon nitride is that it is stable in water, even under extremely acidic or alkali conditions. Apart from that, it is very easy and inexpensive to produce," says Xinchen Wang.
Carbon nitride uses sunlight to extract hydrogen from water. A substance that chemists call a sacrificial reagent absorbs the oxygen from the water. The clever trick here is that the chemists in Potsdam did not need to use a precious metal like platinum. The traditional processes require precious metals, in addition to a semiconductor acting as an aerial for the sunlight, to catalyse the production of hydrogen. The carbon nitride does both jobs at the same time and furthermore acts as a particularly stable organic semiconductor that is much easier to produce than the inorganic materials normally used.
However, only four micromoles of hydrogen per hour bubbled up out of the re-searchers' reaction vessel. When the researchers added the normal quantities of platinum as a catalyst, the yield increased substantially - by a factor of seven.
Wang's scientists are now working on a configuration to combine the production of hydrogen and oxygen. If they are successful, the process of water splitting will be perfect and hydrogen will be a step closer to fulfilling its role as an important source of energy. source
My comment:Hm, it's a very inefficient so far, but if you use it on a lot of water, it might compensate. I guess the problem is what to do with the left-overs, but I'm sure they could think of something. And hydrogen is worthy it. It's really a cool energy source. Even if a little bit explosive.
Physicist develops battery using new source of energyMarch 11th, 2009
Researchers at the University of Miami and at the Universities of Tokyo and Tohoku, Japan, have been able to prove the existence of a "spin battery," a battery that is "charged" by applying a large magnetic field to nano-magnets in a device called a magnetic tunnel junction (MTJ). The new technology is a step towards the creation of computer hard drives with no moving parts, which would be much faster, less expensive and use less energy than current ones. In the future, the new battery could be developed to power cars.
The device created by University of Miami Physicist Stewart E. Barnes, of the College of Arts and Sciences and his collaborators can store energy in magnets rather than through chemical reactions. Like a winding up toy car, the spin battery is "wound up" by applying a large magnetic field --no chemistry involved. The device is potentially better than anything found so far, said Barnes.
"We had anticipated the effect, but the device produced a voltage over a hundred times too big and for tens of minutes, rather than for milliseconds as we had expected," Barnes said.
The secret behind this technology is the use of nano-magnets to induce an electromotive force. It uses the same principles as those in a conventional battery, except in a more direct fashion. The energy stored in a battery is in the form of chemical energy. The new technology converts the magnetic energy directly into electrical energy, without a chemical reaction. The electrical current made in this process is called a spin polarized current and finds use in a new technology called "spintronics."
The new discovery advances our understanding of the way magnets work and its immediate application is to use the MTJs as electronic elements which work in different ways to conventional transistors. Although the actual device has a diameter about that of a human hair and cannot even light up an LED (light-emitting diode--a light source used as electronic component), the energy that might be stored in this way could potentially run a car for miles. The possibilities are endless, Barnes said. source
My comment: I think the scientists underestimate their discovery. If that could be made to work on larger scales, it would be the cleanest form of battery-because you don't have the dangerous chemicals to be recycled or stored on a special place. You just spin it up again. But I think it would be hard to fight with the chemical companies, they are so big and this new mechanism has the power to take their food from the table. And as they said-magnets are everywhere around us.
Self-Organizing Nanotech Could Store 250 DVDs on One Coin-Size SurfaceSapphire crystals may be the next material to transform the electronics industry, thanks to nanotechnology researchers who have announced a new way of storing data that would fit the contents of 250 DVDs on a coin-sized surface. The study, published in Science, illustrates how nanoscale elements can organize themselves over a large sheet of semiconductor film. The researchers expect that when applied to electronic media, their discovery will improve the efficiency of data storage, savings which can then be transferred to improve other pieces of electronics besides just storage, like high-definition screens and solar cells.
Lead researchers Ting Xu from the University of California at Berkeley and Thomas Russell from the University of Massachusetts at Amherst layered the film of block copolymers onto the surface of a commercially available sapphire crystal. When the crystal is cut at an angle—a common procedure known as a miscut—and heated to 1,300 to 1,500 degrees Centigrade for 24 hours, its surface reorganizes into a highly ordered pattern of sawtooth ridges that can then be used to guide the self-assembly of the block polymers [Science Daily].With this technique, the only limit to the size of an array of block copolymers is the size of the sapphire, Xu said. Once a sapphire is heated up and the pattern is created, the template could be reused. Both the crystals and the polymer chains could be obtained commercially, Xu said [PC World]. The researchers say the technology could make nearly perfect arrays of semiconductor material that are about 15 times denser than anything achieved previously [Reuters]. source
My comment: I think I recently wrote about this. Just imagine what could you do with such data-storages. This would open the doors for a completely new ways of entertainment-you could store a 3d movie on it. You could store almost anything on it. 250DVDs are quite much space and this is just the beginning. The question is how medias would evolve to fill that space.