Posts belonging to Category electronics

Printing 3-D Graphene For Tissue Engineering

Ever since single-layer graphene burst onto the science scene in 2004, the possibilities for the promising material have seemed nearly endless. With its high electrical conductivity, ability to store energy, and ultra-strong and lightweight structure, graphene has potential for many applications in electronics, energy, the environment, and even medicine.

Now a team of Northwestern University researchers has found a way to print three-dimensional structures with graphene nanoflakes. The fast and efficient method could open up new opportunities for using graphene printed scaffolds regenerative engineering and other electronic or medical applications.
Led by Ramille Shah, assistant professor of materials science and engineering at the McCormick School of Engineering and of surgery in the Feinberg School of Medicine, and her postdoctoral fellow Adam Jakus, the team developed a novel graphene-based ink that can be used to print large, robust 3-D structures.

People have tried to print graphene before,” Shah said. “But it’s been a mostly polymer composite with graphene making up less than 20 percent of the volume.

With a volume so meager, those inks are unable to maintain many of graphene’s celebrated properties. But adding higher volumes of graphene flakes to the mix in these ink systems typically results in printed structures too brittle and fragile to manipulate. Shah’s ink is the best of both worlds. At 60-70 percent graphene, it preserves the material’s unique properties, including its electrical conductivity. And it’s flexible and robust enough to print robust macroscopic structures. The ink’s secret lies in its formulation: the graphene flakes are mixed with a biocompatible elastomer and quickly evaporating solvents

It’s a liquid ink,” Shah explained. “After the ink is extruded, one of the solvents in the system evaporates right away, causing the structure to solidify nearly instantly. The presence of the other solvents and the interaction with the specific polymer binder chosen also has a significant contribution to its resulting flexibility and properties. Because it holds its shape, we are able to build larger, well-defined objects.
An expert in biomaterials, Shah said 3-D printed graphene scaffolds could play a role in tissue engineering and regenerative medicine as well as in electronic devices. Her team populated one of the scaffolds with stem cells to surprising results. Not only did the cells survive, they divided, proliferated, and morphed into neuron-like cells.


Artificial Synapses Operate Image Classification

In what marks a significant step forward for artificial intelligence, researchers at UC Santa Barbara have demonstrated the functionality of a simple artificial neural circuit. For the first time, a circuit of about 100 artificial synapses was proved to perform a simple version of a typical human task: image classification.

“It’s a small, but important step,” said Dmitri Strukov, a professor of electrical and computer engineering. With time and further progress, the circuitry may eventually be expanded and scaled to approach something like the human brain’s, which has 1015 (one quadrillion) synaptic connections.

For all its errors and potential for faultiness, the human brain remains a model of computational power and efficiency for engineers like Strukov and his colleagues, Mirko Prezioso, Farnood Merrikh-Bayat, Brian Hoskins and Gina Adam. That’s because the brain can accomplish certain functions in a fraction of a second what computers would require far more time and energy to perform.

What are these functions? Well, you’re performing some of them right now. As you read this, your brain is making countless split-second decisions about the letters and symbols you see, classifying their shapes and relative positions to each other and deriving different levels of meaning through many channels of context, in as little time as it takes you to scan over this print. Change the font, or even the orientation of the letters, and it’s likely you would still be able to read this and derive the same meaning.

artificial synapses

In the researchers’ demonstration, the circuit implementing the rudimentary artificial neural network was able to successfully classify three letters (“z”, “v” and “n”) by their images, each letter stylized in different ways or saturated with “noise”. In a process similar to how we humans pick our friends out from a crowd, or find the right key from a ring of similar keys, the simple neural circuitry was able to correctly classify the simple images.

While the circuit was very small compared to practical networks, it is big enough to prove the concept of practicality,” said Merrikh-Bayat. According to Gina Adam, as interest grows in the technology, so will research momentum.

And, as more solutions to the technological challenges are proposed the technology will be able to make it to the market sooner,” she said.

The researchers’ findings are published in the journal Nature.


How To Produce Massively And Easily Solar Panels

Nanoscale materials feature extraordinary, billionth-of-a-meter qualities that transform everything from energy generation to data storage. But while a nanostructured solar cell may be fantastically efficient, that precision is notoriously difficult to achieve on industrial scales. The solution may be self-assembly, or training molecules to stitch themselves together into high-performing configurations.

Now, scientists at the U.S. Department of Energy’s Brookhaven National Laboratory have developed a laser-based technique to execute nanoscale self-assembly with unprecedented ease and efficiency.

solarPanelWe design materials that build themselves,” said Kevin Yager, a scientist at Brookhaven’s Center for Functional Nanomaterials (CFN). “Under the right conditions, molecules will naturally snap into a perfect configuration. The challenge is giving these nanomaterials the kick they need: the hotter they are, the faster they move around and settle into the desired formation. We used lasers to crank up the heat.”


Remote-Controlled Cyborg Beetles

Hard-wiring beetles for radio-controlled flight turns out to be a fitting way to learn more about their biology. Cyborg insect research led by engineers at UC Berkeley and Singapore’s Nanyang Technological University (NTU) is enabling new revelations about a muscle used by beetles for finely graded turns.

Research video showing remote-controlled steering of a giant flower beetle flying untethered. By strapping nanocomputers and wireless radios onto the backs of giant flower beetles and recording neuromuscular data as the bugs flew untethered, scientists determined that a muscle known for controlling the folding of wings was also critical to steering. The researchers then used that information to improve the precision of the beetles’ remote-controlled turns.

This study, published in the journal Current Biology, showcases the potential of wireless sensors in biological research. Research in this field could also lead to applications such as tools to aid search-and-rescue operations in areas too dangerous for humans.
cyborg beetle
What things would you have to strip out in terms of genes or in terms neurosystems to be left with a chassis that is effectively a flyable chassis. Why is an insect not a flying robot, because it has stuff in there that you would like to knock out and then get yourself a chassis“, says Michele Maharbiz, an associate professor in UC Berkeley’s Department of Electrical Engineering and Computer Sciences and the study’s principal investigator.. A chassis like you would find in a car. But while cars were designed with the sole purpose of driving, evolution has hardwired beetles for multiple functions, like mating and eating. All of these need to taken into account when developing a remote controlled beetle. The researchers have made much progress over the years. They have proven they can control the beetles with stimulation to both the brain and muscles. Maharbiz thinks a combination of both techniques will probably be needed to create an ideal cyborg beetle. “At a short term practical level I think that we could stand to build controlled flyers at very small scales this way, in other words using the best of electronics and the best of the natural world,“, adds Maharbiz.

Solar Cell: How To Boost Perovskites Performance

One of the fastest-growing areas of solar energy research is with materials called perovskites. These promising light harvesters could revolutionize the solar and electronics industries because they show potential to convert sunlight into electricity more efficiently and less expensively than today’s silicon-based semiconductors. These superefficient crystal structures have taken the scientific community by storm in the past few years because they can be processed very inexpensively and can be used in applications ranging from solar cells to light-emitting diodes (LEDs) found in phones and computer monitors.
A new study published online in the journal Science by University of Washington (UW) and University of Oxford researchers demonstrates that perovskite materials, generally believed to be uniform in composition, actually contain flaws that can be engineered to improve solar devices even further.
peroskite solar cell
Perovskites are the fastest-growing class of photovoltaic material over the past four years,” said lead author Dane deQuilettes, a UW doctoral student working with David Ginger, professor of chemistry and associate director of the UW Clean Energy Institute.

In that short amount of time, the ability of these materials to convert sunlight directly into electricity is approaching that of today’s silicon-based solar cells, rivaling technology that took 50 years to develop,” deQuilettes said. “But we also suspect there is room for improvement.”

Perovskite solar cells have so far have achieved efficiencies of roughly 20 percent, compared to about 25 percent for silicon-based solar cells. The team found “dark” or poorly performing regions of the perovskite material at intersections of the crystals. In addition, they discovered that they could “turn on” some of the dark areas by using a simple chemical treatment.

3D Hologram From Pop-Up Floating Display

Moving holograms like those used in 3D science fiction movies such as Avatar and Elysium have to date only been seen in their full glory by viewers wearing special glasses.
Now researchers at Swinburne University of Technology (Australia) have shown the capacity of a technique using graphene oxide and complex laser physics to create a pop-up floating display without the need for 3D glasses. Graphene is a two dimensional carbon material with extraordinary electronic and optical properties that offers a new material platform for next-generation nanophototonic devices.

Through a photonic process without involving heat or a change in temperature, the researchers were able to create nanoscale pixels of refractive index – the measure of the bending of light as it passes through a medium – of reduced graphene oxide. This is crucial for the subsequent recording of the individual pixels for holograms and hence naked eye 3D viewing.
3D graphene
If you can change the refractive index you can create lots of optical effects,” Director of Swinburne’s Centre for Micro-Photonics, Professor Min Gu, said.
Our technique can be leveraged to achieve compact and versatile optical components for controlling light. We can create the wide angle display necessary for mobile phones and tablets.


Motorbike Runs On Its Own Generated Energy

Mexican students in Oaxaca City design a motorbike that runs on its own generated energy, without using any combustion. They say their prototype model is a breakthrough invention for eco-friendly motorbikes. What if you could harvest the energy of a moving vehicle to continue to power it? That is the question asked by students of this technical high school college in Oaxaca, Mexico, one year ago. It resulted in this prototype motorcycle called R-Walker created by 17-year-old Victor Garcia.
The project is a prototype that generates its own energy as it goes along: As it goes faster and covers longer distances, it generates more energy. In that way, you don’t have to charge the battery every 6-8 hours,” says Garcia. He calls the process “auto-sustainability.” It’s based on the principle of converting energy through speed and distance travelled; the engine becomes self-sustaining, generating more than 2,000 revolutions per minute. A battery is used to spark ignition, and afterwards without using any combustion the vehicle can carry up to 110 kilograms and travel at more than 60 kilometers per hour.

Co-designer Raul Grajales said R-Walker could bring huge savings for motorcycle users, as well as the environment. “With this, we have reduced the use of 200 batteries a day and seventy percent of pollution, because it does not contaminate and has zero emissions and we use one battery every 5-10 years“, assures Grajales. They built the eco-friendly motorbike from recycled materials, bringing its final price tag to around $200 – a comparatively small sum when considering its potential benefits.

EV: A Thin Film That Produces Oxygen and Hydrogen

A cobalt-based thin film serves double duty as a new catalyst that produces both hydrogen and oxygen from water to feed fuel cells, according to scientists at Rice University. This discovery may lower the cost of future hydrogen electric car.  The inexpensive, highly porous material invented by the Rice lab of chemist James Tour may have advantages as a catalyst for the production of hydrogen via water electrolysis. A single film far thinner than a hair can be used as both the anode and cathode in an electrolysis device.

The researchers led by Rice postdoctoral researcher Yang Yang reported their discovery  in Advanced Materials.

They determined their cobalt film is much better at producing hydrogen than most state-of-the-art materials and is competitive with (and much cheaper than) commercial platinum catalysts. They reported the catalyst also produced an oxygen evolution reaction comparable to current materials.


A side view of a porous cobalt phosphide/phosphate thin film created at Rice University. The robust film could replace expensive metals like platinum in water-electrolysis devices that produce hydrogen and oxygen for fuel cells. The scale bar equals 500 nanometers.

It is amazing that in water-splitting, the same material can make both hydrogen and oxygen,” Tour said. “Usually materials make one or the other, but not both.”

The researchers suggested applying alternating current from wind or solar energy sources to cobalt-based electrolysis could be an environmentally friendly source of hydrogen and oxygen.


Super Bendable Screen

From smartphones and tablets to computer monitors and interactive TV screens, electronic displays are everywhere. As the demand for instant, constant communication grows, so too does the urgency for more convenient portable devices — especially devices, like computer displays, that can be easily rolled up and put away, rather than requiring a flat surface for storage and transportation. A new Tel Aviv University (TAU) study, published recently in Nature Nanotechnology, suggests that a novel DNA-peptide structure can be used to produce thin, transparent, and flexible screens. The research, conducted by Prof. Ehud Gazit and doctoral student Or Berger of the Department of Molecular Microbiology at TAU‘s Faculty of Life Sciences, harnesses bionanotechnology to emit a full range of colors in one pliable pixel layer — as opposed to the several rigid layers that constitute today’s screens.
Researchers tested different combinations of peptides: short protein fragments, embedded with DNA elements which facilitate the self-assembly of a unique molecular architecture. Peptides and DNA are two of the most basic building blocks of life. Each cell of every life form is composed of such building blocks. In the field of bionanotechnology, scientists utilize these building blocks to develop novel technologies with properties not available for inorganic materials such as plastic and metal.

Our material is light, organic, and environmentally friendly,” said Prof. Gazit. “It is flexible, and a single layer emits the same range of light that requires several layers today. By using only one layer, you can minimize production costs dramatically, which will lead to lower prices for consumers as well.”
Once we discovered the DNA-like organization, we tested the ability of the structures to bind to DNA-specific fluorescent dyes,” said Berger. “To our surprise, the control sample, with no added dye, emitted the same fluorescence as the variable. This proved that the organic structure is itself naturally fluorescent.“.

How To convert Your Waste Heat Into Electricity

A mathematical model of heat flow through miniature wires could help develop thermoelectric devices that efficiently convert heat — even their own waste heat — into electricity.

Developed at A*STAR (Singapore), the model describes the movement of vibrations called phonons, which are responsible for carrying heat in insulating materials. Phonons typically move in straight lines in nanowires — threads barely a few atoms wide. Previous calculations suggested that if parts of a nanowire contained random arrangements of two different types of atoms, phonons would be stopped in their tracks. In actual alloy nanowires, though, atoms of the same element might cluster together to form short sections composed of the same elements.

phononsPhonons (vibrations) are typically responsible for carrying heat along a nanowire. A*STAR researchers have used a numerical model to calculate the effects of short-range ordering on phonon behaviour.

Now, Zhun-Yong Ong and Gang Zhang of the A*STAR Institute of High Performance Computing in Singapore have calculated the effects of such short-range order on the behavior of phonons1. Their results suggest that heat conduction in a nanowire does not just depend on the relative concentrations of the alloy atoms and the difference in their masses; it also depends on how the atoms are distributed.