Ultra-fast Data Processing At Nanoscale

Advancement in nanoelectronics, which is the use of nanotechnology in electronic components, has been fueled by the ever-increasing need to shrink the size of electronic devices like nanocomputers in a bid to produce smaller, faster and smarter gadgets such as computers, memory storage devices, displays and medical diagnostic tools.

While most advanced electronic devices are powered by photonics – which involves the use of photons to transmit informationphotonic elements are usually large in size and this greatly limits their use in many advanced nanoelectronics systems. Plasmons, which are waves of electrons that move along the surface of a metal after it is struck by photons, holds great promise for disruptive technologies in nanoelectronics. They are comparable to photons in terms of speed (they also travel with the speed of light), and they are much smaller. This unique property of plasmons makes them ideal for integration with nanoelectronics. However, earlier attempts to harness plasmons as information carriers had little success.

Addressing this technological gap, a research team from the National University of Singapore (NUS) has recently invented a novel “converter” that can harness the speed and small size of plasmons for high frequency data processing and transmission in nanoelectronics.

This innovative transducer can directly convert electrical signals into plasmonic signals, and vice versa, in a single step. By bridging plasmonics and nanoscale electronics, we can potentially make chips run faster and reduce power losses. Our plasmonic-electronic transducer is about 10,000 times smaller than optical elements. We believe it can be readily integrated into existing technologies and can potentially be used in a wide range of applications in the future,” explained Associate Professor Christian Nijhuis from the Department of Chemistry at the NUS Faculty of Science, who is the leader of the research team behind this breakthrough.

This novel discovery was first reported in the journal Nature Photonics.

Source: http://news.nus.edu.sg/

Spintronics

A team of scientists led by Associate Professor Yang Hyunsoo from the National University of Singapore’s (NUS) Faculty of Engineering has invented a novel ultra-thin multilayer film which could harness the properties of tiny magnetic whirls, known as skyrmions, as information carriers for storing and processing data (nanocomputer) on magnetic media. The nano-sized thin film, which was developed in collaboration with researchers from Brookhaven National Laboratory, Stony Brook University, and Louisiana State University, is a critical step towards the design of data storage devices that use less power and work faster than existing memory technologies.

The digital transformation has resulted in ever-increasing demands for better processing and storing of large amounts of data, as well as improvements in hard drive technology. Since their discovery in magnetic materials in 2009, skyrmions, which are tiny swirling magnetic textures only a few nanometres in size, have been extensively studied as possible information carriers in next-generation data storage and logic devices.

Skyrmions have been shown to exist in layered systems, with a heavy metal placed beneath a ferromagnetic material. Due to the interaction between the different materials, an interfacial symmetry breaking interaction, known as the Dzyaloshinskii-Moriya interaction (DMI), is formed, and this helps to stabilise a skyrmion. However, without an out-of-plane magnetic field present, the stability of the skyrmion is compromised. In addition, due to its tiny size, it is difficult to image the nano-sized materials. The NUS team found that a large DMI could be maintained in multilayer films composed of cobalt and palladium, and this is large enough to stabilise skyrmion spin textures.

skyrmionsThis experiment not only demonstrates the usefulness of L-TEM in studying these systems, but also opens up a completely new material in which skyrmions can be created. Without the need for a biasing field, the design and implementation of skyrmion based devices are significantly simplified. The small size of the skyrmions, combined with the incredible stability generated here, could be potentially useful for the design of next-generation spintronic devices that are energy efficient and can outperform current memory technologies,” explains Professor Yang .

The invention was reported in the journal Nature Communications.

Source: http://news.nus.edu.sg

Cheap Batteries For Hydrogen Electric Car

Electrochemical devices are crucial to a green energy revolution in which clean alternatives replace carbon-based fuels. This revolution requires conversion systems that produce hydrogen from water or rechargeable batteries that can store clean energy in cars. Now, Singapore-based researchers have developed improved catalysts as electrodes for efficient and more durable green energy devices.

Electrochemical devices such as batteries use chemical reactions to create and store energy. One of the cleanest reactions is the conversion from water into oxygen and hydrogen. Using energy from the sun, water can be converted into those two elements, which then store this solar energy in gaseous form. Burning hydrogen leads to a chemical explosion that produces water.

For technical applications, the conversion from hydrogen and oxygen into water is done in fuel cells, while some rechargeable batteries use chemical reactions based on oxygen to store and release energy. A crucial element for both types of devices is the cathode, which is the electrical contact where these reactions take place. The research team, which included Zhaolin Liu and colleagues from the A*STAR Institute of Materials Research and Engineering with colleagues from Nanyang Technological University and the National University of Singapore, combined nanometer-sized crystals of this material with sheets of carbon or carbon nanotubes.

oxyde-carbon compositesOxide/carbon composites could power green metal-air batteries

The cost is estimated to be tens of times cheaper than the platinum/carbon composites used at present,” says Liu. Because platinum is expensive, intensive efforts are being made to find alternative materials for batteries.

Source:: http://www.research.a-star.edu.sg/

Liver Cancer: NanoDiamonds Eliminate Resistant Stem Cells

A study led by the National University of Singapore (NUS) found that attaching chemotherapy drug Epirubicin to nanodiamonds effectively eliminates chemoresistant cancer stem cells. The findings were first published online in ACS Nano, the official journal of the American Chemical Society.
liver cancer

The research team, led by Assistant Professor Edward Chow, Junior Principal Investigator at the Cancer Science Institute of Singapore (CSI Singapore) at NUS, demonstrated the use of nanotechnology to repurpose existing chemotherapy drugs as effective agents against chemoresistant cancer stem cells. Chemoresistance, which is the ability of cancer cells to escape chemotherapy treatment, is a primary cause of treatment failure in cancer. Cancer stem cells, a type of cancer cell which initiates the formation of tumours, are commonly found to be more resistant to chemotherapy than the rest of the bulk tumour, which can lead to cancer recurrence following chemotherapy treatment. As such, there is intense interest in developing new drugs or treatment strategies that overcome chemoresistance, particularly in cancer stem cells.

In this study, widely-used chemotherapy drug Epirubicin was attached to nanodiamonds, carbon structures with a diameter of about five nanometres, to develop a nanodiamond-Epirubicin drug delivery complex (EPND). The researchers found that while both standard Epirubicin as well as EPND were capable of killing normal cancer cells, only EPND was capable of killing chemoresistant cancer stem cells and preventing secondary tumour formation in xenograft models of liver cancer.

Source: http://news.nus.edu.sg/

How To Purify Water

A new catalyst could have dramatic environmental benefits if it can live up to its potential, suggests research from Singapore. A*STAR researchers have produced a catalyst with gold-nanoparticle antennas that can improve water quality in daylight and also generate hydrogen as a green energy source. This water purification technology was developed by He-Kuan Luo, Andy Hor and colleagues from the A*STAR Institute of Materials Research and Engineering (IMRE).

photocatalyst

Any innovative and benign technology that can remove or destroy organic pollutants from water under ambient conditions is highly welcome,” explains Hor, who is executive director of the IMRE and also affiliated with the National University of Singapore.

Photocatalytic materials harness sunlight to create electrical charges, which provide the energy needed to drive chemical reactions in molecules attached to the catalyst’s surface. In addition to decomposing harmful molecules in water, photocatalysts are used to split water into its components of oxygen and hydrogen; hydrogen can then be employed as a green energy source.
To demonstrate the efficiency of these catalysts, the researchers studied how they decomposed the dye rhodamine B in water. Within four hours of exposure to visible light 92 per cent of the dye was gone, which is much faster than conventional catalysts that lack gold nanoparticles.
Source: http://www.research.a-star.edu.sg/

Nanoprobe Lightens Up Tumors

Researchers from A*STAR (Singapore) have developed a hybrid metal––polymer nanoparticle that lights up in the acidic environment surrounding tumor cells. Nonspecific probes that can identify any kind of tumor are extremely useful for monitoring the location and spread of cancer and the effects of treatment, as well as aiding initial diagnosis.

Cancerous tumors typically have lower than normal pH levels, which correspond to increased acidity both inside the cells and within the extracellular microenvironment surrounding the cells. This simple difference between tumor cells and normal cells has led several research groups to develop probes that can detect the low pH of tumors using optical imaging, magnetic resonance and positron emission tomography.

Most of these probes, however, target the intracellular pH, which requires the probes to enter the cells in order to work. A greater challenge has been to detect the difference in extracellular pH between healthy tissue and tumor tissue as the pH difference is smaller. Success would mean that the probes are not required to enter the cells.

nanoprobe lightens up tumors
Intravenous administration of a hybrid metal–polymer nanoprobe causes tumor tissue to fluoresce

Our aim is to address the challenge of illuminating tumors universally,” says Bin Liu from the A*STAR Institute of Materials Research and Engineering. Liu’s team, together with colleagues from the National University of Singapore, based their new probe on polymers that self-assemble on gold nanoparticles.
Source: http://www.research.a-star.edu.sg/

360-Degree View Optical Probes In Blood Vessels

Small optical devices are important for diagnostic imaging in the body; they serve, for example, as optical probes in blood vessels or the gastrointestinal tract. For accurate diagnosis, such applications require a 360-degree view of their environment. A microelectromechanical silicon chip developed by researchers from the A*STAR Institute of Microelectronics, Singapore, in collaboration with colleagues from the National University of Singapore, offers a feasible solution for in vivo diagnostics. The chip can rotate scanning laser beams by almost a full turn at high speed.
Polygon A polygon-shaped pyramidal reflector on a silicon microelectromechanical system (MEMS) chip that allows full circumferential diagnostic imaging
Scientists are widely investigating the microelectromechanical systems (MEMS) used by the researchers in Singapore, with the aim of adding complex functionality to optical or mechanical applications. Typically, these systems are complex structures, such as movable parts or mirrors that are edged into a silicon chip. Their small size makes MEMS devices ideal for circumferential diagnostic imaging systems. The small scanning angles, however, limited earlier attempts to fabricate such devices. The difficulty arose from the inability to fully utilize standard MEMS-based actuators and their linear movements for rotational devices.

Source: http://www.research.a-star.edu.sg/

Robot Lifting Loads 500 Times Its Own Weight

Engineering team from the National University of Singapore (NUS) led by Dr Arian Koh has achieved a world record. They have designed an artificial muscle which could carry a weight 80 times its own while extending to five times its original length. The team’s invention will pave the way for the constructing of life-like robots with superhuman strength and ability.
Artificial muscles have been known to extend to only three times its original length when similarly stressed. The muscle’s degree of extensibility is a significant factor contributing to the muscle’s efficiency as it means that it could perform a wider range of operations while carrying heavy loads. Robots, no matter how intelligent, are restricted by their muscles which are able to lift loads only half its own weight – about equivalent to an average human’s strength (though some humans could lift loads up to three times their weight).
Dr Koh and his team used polymers which could be stretched over 10 times their original length. Translated scientifically, this means that these muscles have a strain displacement of 1,000 per cent. A good understanding of the fundamentals was largely the cause of their success, Dr Koh added.

robots
We put theory to good use. Last year, we calculated theoretically that polymer muscles driven by electrical impulse could potentially have a strain displacement of 1,000 per cent, lifting a load of up to 500 times its own weight. So I asked my students to strive towards this Holy Grail, no matter how impossible it sounded,” he said.
Source: http://www.eng.nus.edu.sg/

How To Combat Overheating In Mobile Phones

A team of scientists from Tyndall National Institute at University College Cork and the National University of Singapore have found new ways to combat overheating in mobile phones and laptops, and could also aid in electrical stimulation of tissue repair for wound healing. By finding out how molecules behave in these devices, a ten-fold increase in switching efficiency was obtained by changing just one carbon atom. Dr. Damien Thompson at the Tyndall National Institute, UCC and a team of researchers at the National University of Singapore led by Prof. Chris Nijhuis designed and created the devices, which are based on molecules acting as electrical valves, or diode rectifiers.

molecules pack together

These molecules are very useful because they allow current to flow through them when switched ON and block current flow when switched OFF. The results of the study show that simply adding one extra carbon is sufficient to improve the device performance by more than a factor of ten. We are following up lots of new ideas based on these results, and we hope ultimately to create a range of new components for electronic devices,” explains Dr. Damien Thompson.
Source: http://www.tyndall.ie/node/23446

Non-Invasive Treatment For Deep Cancer

PhotoDynamic therapy (PDT) as a non-invasive treatment of cancer is limited by the penetration depth of visible light needed for its activation. A Bioengineering team from the National University of Singapore – NUS – led by Associate Professor Zhang Yong has invented a novel method which will pave the way for PDT to treat deep-seated cancer as well. The researchers also revealed how they have been able to control gene expression – the release of certain proteins in our body – using their nanoparticles which could convert NIR (Near Infrared) light to UV light (visible light needed for effective activation).
NIR is a safe light as opposed to UV light, which could cause damage to cells. NIR can also penetrate deeper into tissues to target tumours.

Near Infrared Light -NIR-, besides being non-toxic, is able to penetrate deeper into our tissues. When NIR reaches the desired places in the body of the patient, the nanoparticles which we have invented, are able to convert the NIR back to UV light (upconversion) to effectively activate the genes in the way desired – by controlling the amount of proteins expressed each time, when this should take place, as well as how long it should take place” explains Prof Zhang.

Source: http://www.eng.nus.edu.sg/ero/announcement/web-zhangyong0912.pdf