Tag Archives: research

Researchers Develop New Hybrid Solar Panel That Can Generate Power From Rain Too

The researchers at Soochow University in China, have published a paper on the hybrid device that is able to harness the power of sun and rain using a hybrid panel. By attaching a transparent nanogenerator to a silicon solar cell, researchers have designed a device that harvests solar energy in sunny conditions and the mechanical energy of falling raindrops in rainy conditions. The dual functionality of this hybrid panel may provide a way to collect energy with greater efficiency in the midst of constantly changing weather conditions.

Hybrid solar panel can generate power fro rain too
The hybrid solar panel can generate power fro rain too

The hybrid device consists of a conventional silicon solar cell and a Triboelectric Nanogenerator (TENG), which turns the mechanical energy of falling raindrops into electricity. Although previous research has shown that these two types of devices can be connected with an extra wire, in the new design the solar cell and TENG are integrated by sharing a mutual electrode.

The biggest breakthrough in this work is that an integrated generator composed of a solar cell and a TENG was demonstrated through sharing a mutual electrode,

Zhen Wen at Soochow University said,

Compared to previous work, the simple design of the mutual electrode reduces the number of functional layers, which greatly improves the output efficiency.

The mutual electrode not only results in a more compact design, but it also offers advantages to both the solar cell and TENG. In particular, the TENG protects the solar cell by acting as a waterproof barrier and prevents water from penetrating the silicon. The textured electrode surface also greatly overcomes unwanted reflection of light, enhancing light harvesting of the solar panel. The textured surface results in a greater contact area between the TENG and falling raindrops, which improves the overall performance of the nanogenerator.

Due to the unique design, it has advantages of being lightweight and having a high efficiency, The team is now designing a fiber-shaped device and expect to weave them together as a fabric. In near future, it is possible to fabricate such clothing that can generate electricity from sunshine and raindrops, and then use this electricity to power wearable electronic devices.

Researchers From NREL Discovered New Method To Develop Rechargeable Magnesium-metal Battery

A team of researchers from National Renewable Energy Laboratory (NREL) has discovered a new method for developing a rechargeable non-aqueous magnesium-metal battery. A proof-of-concept paper published in Nature Chemistry. It described how the scientists pioneered a method to enable the reversible chemistry of magnesium metal in the noncorrosive carbonate-based electrolytes and tested the concept in a prototype cell. The technology possesses many high potential advantages over conventional lithium-ion batteries. Some upgrades over Li-ion battery with this new kind of battery will be, higher energy density, greater stability, and lower cost.

magnesium-metal batteries
magnesium-metal batteries

NREL researchers Seoung-Bum Son, Steve Harvey, Andrew Norman, and Chunmei Ban are co-authors of the Nature Chemistry white paper, “An Artificial Interphase Enables Reversible Magnesium Chemistry in Carbonate Electrolytes” working with a Time-of-flight secondary ion mass spectrometry. The device enables them to investigate material degradation and failure mechanisms at the micro- to nano-scale.

Chunmei Ban, a scientist in NREL’s Materials Science department and corresponding author of the paper, said,

Being scientists, we’re always thinking: what’s next? The dominant lithium-ion battery technology is approaching the maximum amount of energy that can be stored per volume, so there is an urgent need to explore new battery chemistries that can provide more energy at a lower cost.

Seoung-Bum Son, a former NREL postdoc and scientist at NREL and first author of the paper, thinks this finding will provide a new avenue for magnesium battery design.

An electrochemical reaction powers a battery as ions flow through a liquid (electrolyte) from the negative electrode (cathode) to the positive electrode (anode). For batteries using Lithium, the electrolyte is a salt solution containing lithium ions. It’s also important to make the chemical reaction reversible for the battery to recharge again.

Magnesium (Mg) batteries theoretically contain almost twice as much energy per volume as of lithium-ion batteries. But previous research confronted an obstacle. The chemical reactions of the conventional carbonate electrolyte created a layer on the surface of magnesium that prevented the battery from recharging. The magnesium ions could flow in a reverse direction through a highly corrosive liquid electrolyte, but that blocked the possibility of a successful high-voltage magnesium battery.

The researchers developed an artificial solid-electrolyte interphase from polyacrylonitrile and magnesium-ion salt that protected the surface of the magnesium anode. This protected anode and significantly improved performance of the cell.

In addition to being more readily available than lithium, magnesium has other advantages over the more established battery technology. Firstly, magnesium releases two electrons which is higher lithium’s one, thus giving it the potential to deliver nearly twice as much energy as lithium. And second, magnesium-metal batteries do not experience the growth of crystals that can cause short circuits and consequently dangerous overheating and even fire, making magnesium batteries much safer than lithium-ion batteries.

Researches Solve Problems of Organic Thin Film Transistors By Developing Nanostructured Gate Dielectric

Amorphous silicon-based Thin-film transistors (TFTs) are the foundation of many modern-day technologies, such as smartphones and flat-panel TVs. Still, it comes with a few drawbacks like performance limitations due to limited carrier mobility. Provoking the researchers in search of something better.

As a result, Organic thin-film transistors (OTFTs) were developed. OTFTs have solved the problem with carrier mobility to an extent. Although it introduced new problems such as the critical performance parameter of large threshold voltage instabilities. Threshold voltages—also known as gate voltages—are the minimum voltage differential needed between a gate and the source to create a conducting path between the source and drain terminals.

Nanostructured Gate dielectric opens new possibilities in OTFTs

Latest works of the researchers at Georgia Institute of Technology seems to overcome the voltage instability problem with OTFTs. They have developed a nanostructured gate dielectric that can regulate voltage threshold fluctuations in OTFTs.

gate dielectric is an important component of every thin-film transistor. It acts as the electrically insulating layer between the gate terminal and the semiconductor. It should have a high dielectric constant, be very thin, and have a high dielectric strength for the transistor to function at low voltage.

On applying a voltage across the gate electrode, the resulting electric field across this insulating layer changes the density of carriers in the semiconductor layer. It regulates the current that is flowing between the source and the drain electrodes. Many different materials are used to make this insulating layer. Such as dielectric polymers, inorganic oxides or combinations of different organic and inorganic materials.

The Georgia Tech researchers used Atomic Layer Deposition (ALD) technique to build a thin metal oxide layer on top of a perfluorinated dielectric polymer. They chose ALD for its ability to produce layers that are free from any defects. Bernard Kippelen, a professor at Georgia Tech, and leader of the research said:

The low defect density reduces the diffusion of moisture into the underlying organic semiconductor layer, preventing its degradation.

The performance of the new organic thin-film transistors seems to surpass that of hydrogenated amorphous silicon technology. According to Kippelen, it revolutionizes OTFTs in terms of charge mobility and stability. He stated:

It is premature and difficult at this stage to provide a direct comparison with what is currently on the market; nevertheless, we believe that the level of stability that is achieved is an important step for printed electronics.

Before the future applications, Kippelen and his team will further investigate the mechanical properties of these printed transistors since they show great potential with flexible form factor products. Further information can be found on the Research paper published in the journal Science Advances.

Researcher Create More Lifelike Soft Robots That Can Mimic Biological Muscle

A group of researchers from the University of Colorado in Boulder (US) is working on the next generation of robots. Instead of the metallic droids concept, these robots are made from soft materials that are more similar to biological systems. Such soft robots hold a huge potential for future applications. They can adjust to dynamic environments and also suitable for close human interaction. Christoph Keplinger from the University of Colorado said,

We draw our inspiration from the astonishing capabilities of biological muscle,

The soft devices, including the muscle actuator, can perform a variety of tasks
The soft robots, including the muscle actuator, can perform a variety of tasks

The newly developed class of soft, electrically activated devices are capable of simulating the expansion and contraction of actual muscles. These devices can be constructed from a wide range of low-cost materials. They are able to self-sense their movements and self-heal from electrical damage.

They developed hydraulically amplified self-healing electrostatic (HASEL) actuators which eliminate the bulky, rigid pistons, valves, pumps and motors of conventional robots. The soft structures of HASEL react to applied voltage with a wide range of movement. According to the study published in the journal Science Robotics on January 5, these flexible robots can perform a variety of tasks. They can handle delicate objects like raspberry or raw egg, as well as lift heavy objects. Keplinger said,

HASEL actuators synergize the strengths of soft fluidic and soft electrostatic actuators, and thus combine versatility and performance like no other artificial muscle before,

He also added,

Just like a biological muscle, HASEL actuators can reproduce the adaptability of an octopus arm, the speed of a hummingbird and the strength of an elephant.

HASEL actuators can simulate the strength, speed, flexibility, and efficiency of biological muscle which may enable artificial muscles for human-like robots. HASEL can make next generation of prosthetic limbs more cost-effective and reliable. This is an important step forwards for soft robotics.

The team is already working on new HASEL actuators that would work with five times lower voltage levels than those described in the studies. The voltage published in the papers is similar to the low-current shock one might get from static electricity, and it’s not hazardous to humans.

The work of this researchers promises a huge improvement in the world of robotics and prosthetic limbs. Their dream is to create robotics that is lifelike. More information can be found in an article appeared in Science recently.

Physicists Of University of Rochester Have Created Polariton – A Particle With Negative Mass

A group of researchers led by Nick Vamivakas from the University of Rochester has successfully produced particles which have negative mass in an atomically thin semiconductor material. According to the researchers, they have created a device that can generate LASER light using a significantly small amount of energy. All made possible with the help of this so-called negative mass particles. Quantum physicist Nick Vamivakas from Rochester’s Institute of Optics says,

It also turns out the device we’ve created presents a way to generate laser light with an incrementally small amount of power. Interesting and exciting from a physics perspective,

Polariton – A new particle that has negative mass

Mass is often observed as a resistance or response to a force. It’s harder to push and to stop a bowling ball than a marble because of the inertia associated with the mass of the object. All objects that are made of matter must have the property of ‘mass’. Even elementary particles without rest mass have something called relativistic mass. They react to an externally applied force in the way you expect them to. Particles with ‘negative mass’ however exhibit the opposite reaction to an applied force. They tend to move toward the applied force direction than to move away from it.

“That’s kind of a mind-bending thing to think about because if you try to push or pull it, it will go in the opposite direction from what your intuition would tell you,” says Vamivakas.

The device they created to make negative mass consists of two mirrors. It is used to make an optical microcavity to capture light at different colors of the spectrum depending on the mirror spacing. An atomically thin Molybdenum diselenide semiconductor is then implanted into the microcavity. This interacts with the captured light. The small particles called excitons from the semiconductor combine with photons of the trapped light to form polaritons. This process of an exciton giving up its identity to a photon to produce a polariton results in an object with negative mass associated with it. Simply means when you try to push or pull it, it goes off in the opposite direction to the way you would assume.

The most probable practical applications according to the researchers would be:

  •  The physics of negative mass: It will enrich the understanding of the reaction behavior of polaritons on electric fields and external forces.
  •  As a laser fabrication substrate: Due to polaritons, lasers would function more efficiently than the conventional ones. They will require much lower power input.

Further information is available in the journal Nature Physics, with the title Anomalous dispersion of microcavity trion-polaritons.

Researchers Demonstrate New More Efficient FET By Implementing Negative Capacitance

A group of Researchers from Purdue University in Lafayette, Indiana demonstrated the effect called negative capacitance by making a new type of more energy efficient transistor. This new kind of Field Effect Transistor (FET) proves a theory introduced in 2008 by Supriyo Datta, the Thomas Duncan Distinguished Professor of Electrical and Computer Engineering, and Sayeef Salahuddin, who is a professor of Electrical Engineering and Computer Sciences at the University of California, Berkeley.

A new type of transistor (a) harnesses a property called negative capacitance.
A new type of field effect transistor harnesses a property called negative capacitance.

The researchers from Purdue University made a much thinner layer using the semiconductor Molybdenum disulfide. It creates a channel adjacent to an important part of transistors called the gate. By using a “ferroelectric material” called hafnium zirconium oxide, they created a negative capacitor which is a key component in the newly designed gate.

Capacitance is the property of any dielectric or conductor to store electrical charge. It is ordinarily a positive quantity. With the help of ferroelectric materials, the new FET gate structure allows a negative capacitance. Due to this the energy needed to switch the FET is considerably reduced. This new design just substitutes hafnium oxide with hafnium zirconium oxide. Hafnium oxide is a conventional material to use in modern FETs as a dielectric material to isolate the gate. This work is led by Peide Ye, Richard J. and Mary Jo Schwartz of Purdue University.  Ye said,

The overarching goal is to make more efficient transistors that consume less power, especially for power-constrained applications such as mobile phones, distributed sensors, and emerging components for the internet of things

Transistors act like a tiny electronic switch. They can turn on and off very fast, allowing computers to process information in binary code. A proper switching off state is very important to ensure that no electricity “leaks” through. This switching normally needs a minimum of 60 millivolts for every tenfold increase in current. This requirement called the thermionic limit. However, transistors using negative capacitance can break this fundamental limit, because they can switch at far lower voltages resulting in smaller power consumption.

New findings from the research group have advanced the conventional transistor technology to a much efficient and faster level. Only time will justify if the new ‘negative capacitance‘ FETs can revolutionize the modern electronics.

Micro-spectrometer Sensor Will Let You Check Air Quality Or Blood Sugar – Using Smartphone

Now you can use your smartphone to check how clean the air is, measure the freshness of food or even the level of your blood sugar. This has never been so easy. All credit goes to the new spectrometer sensor which is developed at the Eindhoven University of Technology and can be easily attached to a mobile phone. The little sensor is just as precise as the normal tabletop models used in scientific labs. The researchers published their invention on 20th December in the popular journal Nature Communications.

The blue perforated slab is the upper membrane, with the photonic crystal cavity in the middle
Spectrometer sensor construction: The blue perforated slab is the upper membrane, with the photonic crystal cavity in the middle

Spectrometry is the analysis of the light spectrum. It has an enormous range of applications. Every organic and inorganic substance has its own unique ‘footprint‘ in terms of light absorption and reflection. Thus it can be recognized by spectrometry. But precise spectrometers are bulky and costly since they split up the light into different colors (frequencies), which are then measured separately.

The intelligent sensor developed by Eindhoven researchers is able to make such accurate measurements in an entirely different way. It uses a special photonic crystal cavity that acts as a ‘trap’ of just a few micrometers into which the light falls and cannot escape. This trap is situated in a membrane. In the membrane, the captured light generates a tiny electrical current which can be measured accurately. The accurate working cavity design is made by Žarko Zobenica, a doctoral candidate.

The sensor can measure only a narrow range of light frequencies. To increase the frequency range, the researchers placed two of these membranes above each other closely. The two membranes affect each other. Changing the separation gap between them by a tiny amount also changes the light frequency that the sensor recognizes. To understand this the researchers, supervised by professor Andrea Fiore and associate professor Rob van der Heijden, included a MEMS or micro-electromechanical system.

This mechanism can change the measured frequency by changing the separation between the membranes. In this way, the sensor is able to cover a range of about thirty nanometers. Within which the spectrometer can recognize some hundred thousand frequencies with an exceptional precision. The research team demonstrated several applications like an extremely precise motion sensor and a gas sensor. All made possible by the clever use of the tiny membranes.

As per Professor Fiore‘s expectations, it will take another five years or more before the new spectrometer actually gets into a Smartphone. The main difficulty at this moment is the frequency range covered is still too small. It covers only a few percent of the most common spectrum, the near-infrared.

Given the huge potential and the wide field of applications, micro-spectrometers can become just as important as the camera in the smartphones of future.

ICECool – An Intra-Chip Cooling System That Is More Efficient

In the Moore’s Law race to keep improving computer performance, the IT industry has turned upward, stacking chips like nano-sized 3D skyscrapers. But those stacks have their limits, due to overheating. Researchers from IBM have solved this problem by developing an intra-chip cooling system as a contribution to ICECool program research project by the DARPA (Defense Advanced Research Projects Agency).

ICECool - intra-chip cooling system by IBM
ICECool – intra-chip cooling system by IBM

Today, chips are typically cooled by fans which blow air through heatsinks that sit on top of the chips to carry away excess heat. Advanced water-cooling approaches, which are more effective than air-cooling approaches, replace the heatsink with a cold plate that is fixed on the top of the chip.  But this approach requires extra protection and proper insulation of the chip because of the electrical conductivity of water. Neither of these technologies can cool down the chip much efficiently. Here comes the ICECool that cools the chip down from the inside rather than just from the upper surface.

ICECool uses a nonconductive fluid to bring the fluid into the chip. This completely eliminates the need for a barrier between the chip and fluid. It not only delivers a lower device junction temperature, but also reduces system size, weight, and power consumption significantly. The tests performed on the IBM Power 7+ chips demonstrated junction temperature reduction by 25ᵒ C, and chip power usage reduction by 7 percent compared to traditional air cooling. This is clearly a great achievement when the operating cost is much smaller than the conventional cooling technologies.

IBM’s ICECool intra-chip cooling system solves the problem of cooling the 3D “skyscraper” chips by pumping a heat-extracting dielectric fluid right into microscopic gaps, some no thicker than a single strand of hair, between the chips at any level of the stack. Being nonconducting, the dielectric fluid used in ICECool can come into contact with electrical connections without causing any short circuit, so is not limited to one part of a chip or stack. Based on the tests with IBM Power Systems, ICECool technology could reduce the cooling energy for a traditional air-cooled data center by more than 90 percent.

Researchers Developed Low Cost Battery From Graphite Waste

Lithium-ion batteries are flammable and the price of the raw material is increasing. Scientists and engineers have been trying to find out a safe yet efficient alternative to the Lithium-ion technology. The researchers of Empa and ETH Zürich have discovered promising approaches as to how we might produce powerful batteries out of waste graphite and scrap metal.

Kostiantyn Kravchyk and Maksym Kovalenko, the two chief researchers of the Empa’s Laboratory for Thin Films and Photovoltaics, led the research group. Their ambitious goal is to make a battery out of the most common elements in the Earth’s crust – such as graphite or aluminum. These metals offer a high degree of safety, even if the anode is made of pure metal. This also enables the assembly of the batteries in a very simple and inexpensive way.

In typical lithium-ion battery design, the negative electrode or anode is made from graphite. This new design, however, uses graphite as the positive electrode or cathode. In order to make such batteries run, the liquid electrolyte needs to consist of special ions that form a kind of melt and do not crystallize at room temperature. The metal ions move back and forth between the cathode and the anode in this “cold melt”, encased in a thick covering of chloride ions.

Alternatively, large but lightweight and metal-free organic anions could be used. But, this raises some questions which cannot be solved easily – where are these “large” ions supposed to go when the battery is charged? What could be a suited cathode material? In comparison, the cathode of the lithium-ion battery is made of a metal oxide which can easily absorb the small lithium cations during charging. This does not work for such large organic ions.

To solve the problem, Kovalenko’s team came up with a unique and tricky solution: the researchers turned the principle of the lithium-ion battery upside down. In Kovalenko’s battery, the graphite is used as a cathode; i.e., the positive pole. The thick anions are deposited in the intermediate spaces in the graphite. While searching for the “right” graphite, they found that waste graphite produced in steel production (known as kish graphite) works the best as a cathode material. Natural graphite is suitable when it is in the form of coarse flakes and not too finely ground.

Researchers Developed New Efficient, Thin, and Flexible Cooling Device

Engineers and scientists from the UCLA Henry Samueli School of Engineering and Applied Science and SRI International, California, have created a thin flexible device that could keep smartphones and laptop computers cool and prevent overheating. The component is based on the electrocaloric effect – a phenomenon where the temperature of material changes when an electric field is applied to it. The research has been published in Science.

Thin, flexible cooling device
Thin, flexible cooling device

The system’s flexibility also allows it to be used in wearable electronics, robotic systems, and new types of personalized cooling systems. It is the first demonstration of a solid-state cooling device based on the electrocaloric effect. The method devised by UCLA and SRI researchers is very energy-efficient. It uses a thin polymer film that transfers heat from the heat source – a battery or a processor – to a heat sink, and alternates contact between the two by switching on and off the electric voltage.

Because the polymer film is very flexible, the system can be used in devices with complex shapes or moving surfaces. Body tracking wearable devices can easily accommodate this flexible cooling device. Such cooling pad could keep a person comfortable in a hot office and thus lower the electricity consumption for air conditioning. Or it could be placed in a shoe to keep a runner comfortable while running in the sun. It’s like a personal air conditioner.

The tendency of flexible electronics to overheat remains a major challenge for engineers. The cooling systems in larger devices like air conditioners and refrigerators, which use vapor compression, are just too large for mobile electronics. The new cooling device produces a specific cooling power of 2.8 watts per gram and a COP of 13. This is more efficient and compact than the existing surface-mountable solid-state cooling technologies, opening a path to using the technology for a variety of practical applications.

Roy Kornbluh, an SRI research engineer, said,

The development of practical efficient cooling systems that do not use chemical coolants that are potent greenhouse gases is becoming even more important as developing nations increase their use of air conditioning.