Author: Madhu Reddy

Hyperlens significantly boosts image resolution of microscopic objects

Posted by on Leave a Comment

hyperlens

Scientists at the University of Buffalo have created a prototype visible light “hyperlens” that may help image objects that were once only clearly viewable through electron microscopes (Credit: University of Buffalo)

Using visible light magnified through a compound series of lenses to image small objects, standard optical microscopes have been with us for many centuries. Whilst continually being improved, the result of these many advances of optics and image-capturing techniques means that many high-end optical microscopes have now reached the limit of magnification possible as they push the resolution properties of light itself. In an attempt to resolve this issue, scientists at the University of Buffalo (UB) have created a prototype visible light “hyperlens” that may help image objects once only clearly viewable through electron microscopes.

The resolution limit for images captured by an optical microscope system is due to the diffraction of light from a viewed object. Put simply, as light passes through the circular aperture of a microscope lens, the light waves from very small points of light interfere with each other on the way through, causing the image to blur.

The diffraction problem is due to a phenomenon known as the “Rayleigh criterion”, which specifies the minimum separation distance between two observed objects that can be resolved into distinct objects. As the size of the aperture used in relation to the wavelength of light is inherent in the criterion’s formula, then the smaller the aperture and the closer in size an object is to the wavelength of light itself, the greater the diffraction and the more the image is blurred.

UB researchers working on metamaterials – that is, artificial materials engineered with properties not yet found in nature – claim to have overcome this diffraction limit problem by creating a photonic hyperlens that they say changes evanescent waves of light into propagating waves. In other words, they use these lenses to alter the properties of light from that which loses intensity rapidly (evanescent waves) to those that are increased in intensity (propagating waves).

The metamaterial hyperlenses first developed were made of silver and a dielectric insulating material arranged in concentric rings. Whilst this type of hyperlens worked very well at specific wavelengths of light, it suffered from large losses at resonant frequencies.

To help improve on this, UB researchers arranged minute slices of gold and PMMA (a clear thermoplastic) into a radiating semi-circular shape that the researchers point out looks like a very tiny Slinky suspended in its movement. This new shape turned out to be a much improved one, as it effectively ameliorates the diffraction limit on objects viewed in the visible light range.

An immediate use for such a device, the team believes, is that it could be combined with an optical waveguide to produce a hyperlens-based medical endoscope. As even high-resolution endoscopes can only resolve images of objects around 10,000 nanometers in size, a hyperlens-equipped endoscope could potentially increase that resolution to at least 250 nanometers or more, and may provide medical practitioners with that ability to locate tiny, hard-to-find cancers that could help catch the disease before it has time to spread.

“There is a great need in healthcare, nanotechnology and other areas to improve our ability to see tiny objects that elude even the most powerful optical systems,” said Natalia Litchinitser, PhD, professor of electrical engineering at UB. “The hyperlens we are developing is, potentially, a giant step toward solving this problem.”

The researchers also believe that the hyperlens may even eventually be capable of imaging single molecules in visible light, which has enormous implications for research in many fields, particularly chemistry and biology. In the field of physics, such a lens may also help such things as optical nanolithography, where light is shone through a mask to create a pattern on polymer or graphene films for integrated circuits, along with developments in the next generation of optoelectronic electronics, including sensors and data storage drives.

References: http://www.gizmag.com

Team presents induction-powered biosensor chips detecting many molecules in vivo

Posted by on Leave a Comment

achipplacedu

It’s only a centimeter long, it’s placed under your skin, it’s powered by a patch on the surface of your skin and it communicates with your mobile phone. The new biosensor chip developed at EPFL is capable of simultaneously monitoring the concentration of a number of molecules, such as glucose and cholesterol, and certain drugs.

The future of medicine lies in ever greater precision, not only when it comes to diagnosis but also drug dosage. The blood work that medical staff rely on is generally a snapshot indicative of the moment the blood is drawn before it undergoes hours – or even days – of analysis.
Several EPFL laboratories are working on devices allowing constant analysis over as long a period as possible. The latest development is the biosensor chip, created by researchers in the Integrated Systems Laboratory working together with the Radio Frequency Integrated Circuit Group. Sandro Carrara is unveiling it today at the International Symposium on Circuits and Systems (ISCAS) in Lisbon.

Autonomous operation

“This is the world’s first chip capable of measuring not just pH and temperature, but also metabolism-related molecules like glucose, lactate and cholesterol, as well as drugs,” said Dr Carrara. A group of electrochemical sensors works with or without enzymes, which means the device can react to a wide range of compounds, and it can do so for several days or even weeks.
This one-centimetre square device contains three main components: a circuit with six sensors, a control unit that analyses incoming signals, and a radio transmission module. It also has an induction coil that draws power from an external battery attached to the skin by a patch. “A simple plaster holds together the battery, the coil and a Bluetooth module used to send the results immediately to a mobile phone,” said Dr Carrara.

1-achipplacedu

Contactless, in vivo monitoring

The chip was successfully tested in vivo on mice at the Institute for Research in Biomedicine (IRB) in Bellinzona, where researchers were able to constantly monitor glucose and paracetamol levels without a wire tracker getting in the way of the animals’ daily activities. The results were extremely promising, which means that clinical tests on humans could take place in three to five years – especially since the procedure is only minimally invasive, with the chip being implanted just under the epidermis.
“Knowing the precise and real-time effect of drugs on the metabolism is one of the keys to the type of personalised, precision medicine that we are striving for,” said Dr Carrara.

References: http://phys.org

Researchers develop two-legged robot that walks like an animated character

Posted by on Leave a Comment

70-researchersd

When Walt Disney created Mickey Mouse, he didn’t give much thought to how he might bring his character to life in the real world. But robotics now puts that possibility within reach, so Disney researchers have found a way for a robot to mimic an animated character’s walk.

Beginning with an animation of a diminutive, peanut-shaped character that walks with a rolling, somewhat bow-legged gait, Katsu Yamane and his team at Disney Research Pittsburgh analyzed the character’s motion to design a robotic frame that could duplicate the walking motion using 3D-printed links and servo motors, while also fitting inside the character’s skin. They then created control software that could keep the robot balanced while duplicating the character’s gait as closely as possible.
“The biggest challenge is that designers don’t necessarily consider physics when they create an animated character,” said Yamane, senior research scientist. Roboticists, however, wrestle with physical constraints throughout the process of creating a real-life version of the character.
“It’s important that, despite physical limitations, we do not sacrifice style or the quality of motion,” Yamane said. The robots will need to not only look like the characters, but move in the way people are accustomed to seeing those characters move.
Yamane and Joohyung Kim of Disney Research Pittsburgh and Seungmoon Song, a Ph.D. student at Carnegie Mellon University’s Robotics Institute, focused first on developing the lower half of such a robot.
“Walking is where physics matter the most,” Yamane explained. “If we can find a way to make the lower half work, we can use the exact same procedure for the upper body.”
They will describe the techniques and technologies they used to create the bipedal robot at the IEEE International Conference on Robotics and Automation, ICRA 2015, May 26-30 in Seattle.
Compromises were inevitable. For instance, an analysis of the animated character showed that its ankle and foot had three joints, each of which had three degrees of freedom. Integrating nine actuators in a foot isn’t practical. And the researchers realized that the walking motion in the animation wasn’t physically realizable – if the walking motion in the animation was used on a real robot, the robot would fall down.
By studying the dynamics of the walking motion in simulation, the researchers realized they could mimic the motion by building a leg with a hip joint that has three degrees of freedom, a knee joint with a single degree of freedom and an ankle with two degrees of freedom.
Because the joints of the robot differ from what the analysis showed that the animated character had, the researchers couldn’t duplicate the character’s joint movements, but identified the position trajectories of the character’s pelvis, hips, knees, ankle and toes that the robot would need to duplicate. To keep the robot from falling, the researchers altered the motion, such as by keeping the character’s stance foot flat on the ground.
They then optimized the trajectories to minimize any deviation from the target motions, while ensuring that the robot was stable.

References: http://phys.org

Nano memory cell can mimic the brain’s long-term memory

Posted by on Leave a Comment

150512075107_1_540x360

RMIT University researchers have mimicked the way the human brain processes information with the development of an electronic long-term memory cell.

Researchers at the MicroNano Research Facility (MNRF) have built the one of the world’s first electronic multi-state memory cell which mirrors the brain’s ability to simultaneously process and store multiple strands of information.

The development brings them closer to imitating key electronic aspects of the human brain — a vital step towards creating a bionic brain — which could help unlock successful treatments for common neurological conditions such as Alzheimer’s and Parkinson’s diseases.

The discovery was recently published in the materials science journalAdvanced Functional Materials.

Project leader Dr Sharath Sriram, co-leader of the RMIT Functional Materials and Microsystems Research Group, said the ground-breaking development imitates the way the brain uses long-term memory.

“This is the closest we have come to creating a brain-like system with memory that learns and stores analog information and is quick at retrieving this stored information,” Dr Sharath said.

“The human brain is an extremely complex analog computer… its evolution is based on its previous experiences, and up until now this functionality has not been able to be adequately reproduced with digital technology.”

The ability to create highly dense and ultra-fast analog memory cells paves the way for imitating highly sophisticated biological neural networks, he said.

The research builds on RMIT’s previous discovery where ultra-fast nano-scale memories were developed using a functional oxide material in the form of an ultra-thin film — 10,000 times thinner than a human hair.

Dr Hussein Nili, lead author of the study, said: “This new discovery is significant as it allows the multi-state cell to store and process information in the very same way that the brain does.

“Think of an old camera which could only take pictures in black and white. The same analogy applies here, rather than just black and white memories we now have memories in full color with shade, light and texture, it is a major step.”

While these new devices are able to store much more information than conventional digital memories (which store just 0s and 1s), it is their brain-like ability to remember and retain previous information that is exciting.

“We have now introduced controlled faults or defects in the oxide material along with the addition of metallic atoms, which unleashes the full potential of the ‘memristive’ effect — where the memory element’s behaviour is dependent on its past experiences,” Dr Nili said.

Nano-scale memories are precursors to the storage components of the complex artificial intelligence network needed to develop a bionic brain.

Dr Nili said the research had myriad practical applications including the potential for scientists to replicate the human brain outside of the body — which would remove the ethical barriers involved in experimenting on humans.

“If you could replicate a brain outside the body, it would minimise ethical issues involved in treating and experimenting on the brain which can lead to better understanding of neurological conditions,” Dr Nili said.

The research, supported by the Australian Research Council, was conducted in collaboration with the University of California Santa Barbara.

 References:http://www.sciencedaily.com/