Meet the Nanomachines That Could Drive a Medical Revolution

A group of physicists recently built the smallest engine ever created from just a single atom. Like any other engine it converts heat energy into movement — but it does so on a smaller scale than ever seen before. The atom is trapped in a cone of electromagnetic energy and lasers are used to heat it up and cool it down, which causes the atom to move back and forth in the cone like an engine piston.

The scientists from the University of Mainz in Germany who are behind the invention don’t have a particular use in mind for the engine. But it’s a good illustration of how we are increasingly able to replicate the everyday machines we rely on at a tiny scale. This is opening the way for some exciting possibilities in the future, particularly in the use of nanorobots in medicine, that could be sent into the body to release targeted drugs or even fight diseases such as cancer.

Nanotechnology deals with ultra-small objects equivalent to one billionth of a meter in size, which sounds an impossibly tiny scale at which to build machines. But size is relative to how close you are to an object. We can’t see things at the nanoscale with the naked eye, just as we can’t see the outer planets of the solar system. Yet if we zoom in — with a telescope for the planets or a powerful electron microscope for nano-objects — then we change the frame of reference and things look very different.

However, even after getting a closer look, we still can’t build machines at the nanoscale using conventional engineering tools. While regular machines, such as the internal combustion engines in most cars, operate according to the rules of physics laid out by Isaac Newton, things at the nanoscale follow the more complex laws of quantum mechanics. So we need different tools that take into account the quantum world in order to manipulate atoms and molecules in a way that uses them as building blocks for nanomachines. Here are four more tiny machines that could have a big impact.

1- Graphene engine for nanorobots

Researchers from Singapore have recently demonstrated a simple but nano-sized engine made from a highly elastic piece of graphene. Graphene is a two-dimensional sheet of carbon atoms that has exceptional mechanical strength. Inserting some chlorine and fluorine molecules into the graphene lattice and firing a laser at it causes the sheet to expand. Rapidly turning the laser on and off makes the graphene pump back and forth like the piston in an internal combustion engine.

The researchers think the graphene nano-engine could be used to power tiny robots, for example to attack cancer cells in the body. Or it could be used in a so-called “lab-on-a-chip” — a device that shrinks the functions of a chemistry lab into tiny package that can be used for rapid blood tests, among other things.

2- Frictionless nano-rotor

Molecular motor.
Image credit: Palma, C.-A.; Kühne, D.; Klappenberger, F.; Barth, J.V.; Technische Universität München

Molecular motor. Image credit: Palma, C.-A.; Kühne, D.; Klappenberger, F.; Barth, J.V.; Technische Universität München

The rotors that produce movement in machines such as aircraft engines and fans all usually suffer from friction, which limits their performance. Nanotechnology can be used to create a motor from a single molecule, which can rotate without any friction. Normal rotors interact with the air according to Newton’s laws as they spin round and so experience friction. But, at the nanoscale, molecular rotors follow quantum law, meaning they don’t interact with the air in the same way and so friction doesn’t affect their performance.

Nature has actually already shown us that molecular motors are possible. Certain proteins can travel along a surface using a rotating mechanism that create movement from chemical energy. These motor proteins are what cause cells to contract and so are responsible for our muscle movements.

Researchers from Germany recently reported creating a molecular rotor by placing moving molecules inside a tiny hexagonal hole known as a nanopore in a thin piece of silver. The position and movement of the molecules meant they began to rotate around the hole like a rotor. Again, this form of nano-engine could be used to power a tiny robot around the body.

3- Controllable nano-rockets

A rocket is the fastest man-made vehicle that can freely travel across the universe. Several groups of researchers have recently constructed a high-speed, remote-controlled nanoscale version of a rocket by combining nanoparticles with biological molecules.

In one case, the body of the rocket was made from a polystyrene bead covered in gold and chromium. This was attached to multiple “catalytic engine” molecules using strands of DNA. When placed in a solution of hydrogen peroxide, the engine molecules caused a chemical reaction that produced oxygen bubbles, forcing the rocket to move in the opposite direction. Shining a beam of ultra-violet light on one side of the rocket causes the DNA to break apart, detaching the engines and changing the rocket’s direction of travel. The researchers hope to develop the rocket so it can be used in any environment, for example to deliver drugs to a target area of the body.

4- Magnetic nano-vehicles for carrying drugs

Magnetic nanoparticles. Image credit: Tapas Sen, author provided

My own research group is among those working on a simpler way to carry drugs through the body that is already being explored with magnetic nanoparticles. Drugs are injected into a magnetic shell structure that can expand in the presence of heat or light. This means that, once inserted into the body, they can be guided to the target area using magnets and then activated to expand and release their drug.

The technology is also being studied for medical imaging. Creating the nanoparticles to gather in certain tissues and then scanning the body with a magnetic resonance imaging (MRI) could help highlight problems such as diabetes.

Tapas Sen, Reader in Nanomaterials Chemistry, University of Central Lancashire

This article was originally published on The Conversation. Read the original article.

ORIGINAL: Singularity Hub

BY TAPAS SEN

ON APR 21, 2016

Scientists have discovered a new state of matter, called 'Jahn-Teller metals'

Image: High temperature superconductor levitating above a ring magnet. Credit: Julian Litzel/Wikimedia

And it could be the key to understanding one of the biggest mysteries in physics today - high-temperature superconductors.

An international team of scientists has announced the discovery of a new state of matter in a material that appears to be an 

• insulator, 
• superconductor, 
• metal and 
• magnet 

all rolled into one, saying that it could lead to the development of more effective high-temperature superconductors.

Why is this so exciting?
Well, if these properties are confirmed, this new state of matter will allow scientists to better understand why some materials have the potential to achieve superconductivity at a relativity high critical temperature (Tc) - "high" as in −135 °C as opposed to −243.2 °C. Because superconductivity allows a material to conduct electricity without resistance, which means no heat, sound, or any other form of energy release, achieving this would revolutionise how we use and produce energy, but it’s only feasible if we can achieve it at so-called high temperatures.

As Michael Byrne explains at Motherboard, when we talk about states of matter, it’s not just 

• liquids
• plasmas 

that we have to think about. We also have to consider the more obscure states that don’t occur in nature, but are rather created in the lab -

• Bose–Einstein condensate
• degenerate matter
• supersolids and
• superfluids
• quark-gluon plasma

for example. 

By introducing rubidium into carbon-60 molecules - more commonly known as 'buckyballs' - a team led by chemist Kosmas Prassides from Tokohu University in Japan was able to change the distance between them, which forced them into a new, crystalline structure. When put through an array of tests, this structure displayed a combination of insulating, superconducting, metallic, and magnetic phases, including a brand new one, which the researchers have named 'Jahn-Teller metals'. 

Named after the Jahn-Teller effect, which is used in chemistry to describe how at low pressures, the geometric arrangement of molecules and ions in an electronic state can become distorted, this new state of matter allows scientists to transform an insulator - which can’t conduct electricity - into a conductor by simply applying pressure. Byrne explains at Motherboard: 

"This is what the rubidium atoms do: apply pressure. Usually when we think about adding pressure, we think in terms of squeezing something, forcing its molecules closer together by brute force. But it's possible to do the same thing chemically, tweaking the distances between molecules by adding or subtracting some sort of barrier between them - sneaking in some extra atoms, perhaps.

What happens in a Jahn-Teller metal is that as pressure is applied, and as what was previously an insulator - thanks to the electrically-distorting Jahn-Teller effect - becomes a metal, the effect persists for a while. The molecules hang on to their old shapes. So, there is an overlap of sorts, where the material still looks an awful lot like an insulator, but the electrons also manage to hop around as freely as if the material were a conductor."

And it’s this transition phase between insulator and conductor that, until now, scientists have never seen before, and hints at the possibility of transforming insulating materials into super-valuable superconducting materials. And this buckyball crystalline structure appears to be able to do it at a relatively high TC. "The relationship between the parent insulator, the normal metallic state above Tc, and the superconducting pairing mechanism is a key question in understanding all unconventional superconductors," the team writes in Science Advances.

There’s a whole lot of lab-work to be done before this discovery will mean anything for practical energy production in the real world, but that’s science for you. And it’s got people excited already, as chemist Elisabeth Nicol from the University of Guelph in Canada told Hamish Johnston at PhysicsWorld: "Understanding the mechanisms at play and how they can be manipulated to change the Tc surely will inspire the development of new [superconducting] materials".

ORIGINAL: Science Alert

BEC CREW

12 MAY 2015

For First Time, Researchers Demonstrate Heat and Sound Are Magnetic

 Photo: Ohio State University

Earlier this month, we reported on research demonstrating that heat propagates as a wave through graphene rather than as vibrations of atoms the way it does in 3-D materials. In 3-D materials, the collective state of those vibrating atoms is known as phonons.

For the first time, researchers at Ohio State University (OSU) have demonstrated that acoustic phonons, which can carry both heat and sound, have magnetic properties that allow them to be manipulated with magnetism.

In research published in the journal Nature Materials, the OSU researchers applied a magnetic field equivalent to that inside a magnetic resonance imaging (MRI) device (in this case, the magnet was reported to be fairly powerful at seven Tesla). They discovered that they could reduce the amount of heat flowing through a semiconductor by 12 percent.

“This adds a new dimension to our understanding of acoustic waves,” said Joseph Heremans, professor of mechanical engineering at Ohio State, in a press release. “We’ve shown that we can steer heat magnetically. With a strong enough magnetic field, we should be able to steer sound waves, too.”

Before anyone starts thinking about the discovery’s applicability to heat management in computers, they should keep in mind that the semiconductor had to be kept at temperatures very close to absolute zero (specifically, -268 degrees Celsius) in order for the researchers to measure the movements of the phonons.

In fact, it was the complexity of taking the measurements that had prevented researchers from recognizing the magnetic properties of phonons previously. In order to take thermal measurements at such a low temperature, Hyungyu Jin, a postdoctoral researcher and lead author of the study, used the semiconductor indium antimonide and shaped it into a lopsided tuning fork in which one arm was 4 millimeters wide and the other was 1 mm wide. Then he placed a heater at the base of each arm.

At normal temperatures, the ability of the material to transfer heat would be solely dependent on the kind of atoms in the material. But near absolute zero, the ability of the material to transfer heat can be determined by the physical size of the material. In this case, the difference in the sizes of the fork arms was significant. Phonons more easily filled the wider arm.

“Imagine that the tuning fork is a track, and the phonons flowing up from the base are runners on the track,” explained Heremans in the press release. “The runners who take the narrow side of the fork barely have enough room to squeeze through, and they keep bumping into the walls of the track, which slows them down. The runners who take the wider track can run faster, because they have lots of room.”

Eventually they all end up at their respective finish lines. But the track’s geometry determines just how quickly.

With this understanding, Jin was able to compare the temperature changes in the two fork arms. He first took the measurements without a magnet and then with one. With the magnet on, the heat flow through the larger arm slowed down by 12 percent.

Now that the researchers have measured magnetism’s effect on heat, they want to move on to see if they can use it to deflect sound waves.

Learn More Ohio State Universitygrapheneheatmagnetismphononssemiconductorssound waves

ORIGINAL: Spectrum
By Dexter Johnson
24 Mar 2015

New paper claims that the EM Drive doesn't defy Newton's 3rd law after all

By Elvis Popovic

So... it could still get us to Mars in 70 days?

Physicists have just published new calculations that suggest the controversial EM drive - or electromagnetic drive - could actually work, and doesn't defy Newton's third law after all.

In case you've missed the hype, here's a quick catch-up: a lot of space lovers are freaking out about the EM drive because of claims it could get humans to Mars in just 10 weeks, but just as many are sick of hearing about it, because, on paper at least, it doesn't work within the laws of physics.

Despite that not-insignificant setback, the EM drive shows no signs of quitting, and test after test - including trials by NASA scientists at the Eagleworks lab, and an independent researcher in Germany - has conceded that the propulsion system, somehow, does produce thrust.

Why is that so surprising? That's because of how the EM drive is supposed to work, in theory at least. First designed by British scientist Roger Shawyer back in 1999, the EM drive uses electromagnetic waves as fuel, and creates thrust by bouncing those microwaves back and forth within a metal cavity to trigger motion.

According to Shawyer's calculations, that could produce enough thrust to blast humans to Mars in just 70 days, and potentially even help us reach the next Solar System, Alpha Centauri, in just 92 years, all without the need for heavy, expensive rocket fuel.

That sounds pretty incredible, right? But there's one big problem - according to Newton's third law, everything must have an equal and opposite reaction, which means that something needs to be pushed out the back of propulsion system for it to move forwards. And, you pretty quickly see the dilemma - the EM drive doesn't use any fuel propellants, and so it doesn't have an exhaust, and so... it can't produce thrust. Even though it does.

Now that we've taken that round-trip right back to the dilemma we started with, let's present you with a potential solution, from physicists at the University of Helsinki in Finland. According to their new peer-reviewed study published in AIP Advances, the EM drive doesn't actually defy Newton's third law, because it does 

According to the researchers, the exhaust being blasted out is actually light, or more specifically, photons that have become paired up with another out-of-phase photon in order to shoot out of the metal cavity and produce thrust. 

So if that's the case, why hasn't anyone detected it before?

The researchers predict that's because photons need to become paired up in order to escape the fuel cavity, but the two photons in those pairs are out of phase, which means they completely cancel each other out and have no net electromagnetic field. If you think of it like waves of water, if the crest of one wave occurs at the exact same time as the trough of another, they'll cancel each other out and produce a flat patch of water - despite the fact that two waves are still passing through it. 

That's what's happening with the photons, so, in other words, the exhaust photons become invisible from an electromagnetic point of view because they're being masked by their out-of-sync partner.

"The EM drive operates by the same principle, for example, as a jet engine, where the high speed exhaust gases backwards (opposite reaction) push the airplane forwards," one of the researchers Arto Annila, told ScienceAlert over email. 

"Light at microwave lengths is the fuel that's being fed into the cavity ... and the EM drive exhausts backwards paired photons," he says. "When two photons travel together, but having opposite phases, then the pair has no net electromagnetic field, and hence it will not reflect back from the metal walls, but goes through."

And those escaping photons are the equal and opposite reaction that's producing the EM drive's thrust.

To be clear, this is just a hypothesis based on theoretical calculations. But it's not the first time photons have been used to propel spacecraft forward - it's also the idea that Bill Nye's solar sail is based on.

Annila is now hoping that engineers will take on the challenge of testing for these exhaust photon pairs in order to test whether their hypothesis holds up.

And that's going to be a challenge in itself, because without an electromagnetic signature, researchers are going to have to detect them by looking for "excess energy density above the surrounding background density of the gravitational field," Annila explained. That requires a device called an interferometer - not dissimilar to the ones that detect gravitational waves.

But if scientists can verify that these paired photons really are being pushed out the back, sh*t's going to get real for EM drives, because it'll help engineers design better cavities and produce even more thrust. 

"If our proposal is found worthy then EM drive research is no longer questioned but propelled," said Annila.

But as exciting as that is, for Annila the space travel aspect is less interesting than the fundamental physics behind the controversial propulsion system.

"In history often curious phenomena and perplexing observations have opened up a whole new paradigm," he says. Maybe this time, it'll open up a whole new pathway to the Universe. Watch this space.

ORIGINAL: Science Alert

FIONA MACDONALD

16 JUN 2016