Device stores twice the energy of microbatteries currently used in transmitters. By Tom Rickey:
RICHLAND, Wash. – Scientists have created a microbattery that packs twice the energy compared to current microbatteries used to monitor the movements of salmon through rivers in the Pacific Northwest and around the world.
The battery, a cylinder just slightly larger than a long grain of rice, is certainly not the world’s smallest battery, as engineers have created batteries far tinier than the width of a human hair. But those smaller batteries don’t hold enough energy to power acoustic fish tags. The new battery is small enough to be injected into an organism and holds much more energy than similar-sized batteries.
A battery small enough to be injected, energetic enough to track salmon - [Link]
A research team from National Taiwan University, National Taipei University of Technology and Chang Gung University have described how they developed a free-swimming remote-controlled bare die at the IEEE International Solid-State circuits Conference (ISSCC) in San Francisco. The 21.2 mm square die made by TSMC using a 0.35 µm process, is able to travel at 0.3 mm/s submerged in a liquid. A similar device was presented at the ISSCC in 2012, which used Lorentz forces for propulsion. This design however uses electrodes along the four edges of the chip to generate bubbles as a product of electrolysis. [via]
A Free-Swimming Chip - [Link]
In a paper published in Nature Communications researchers at IBM describe how they have built a silicon-based receiver chip incorporating GFETs or Graphene Field Effect Transistors (the purple structure in the photo) into the circuit. The multi-stage receiver integrated circuit consists of 3 graphene transistors, 4 inductors, 2 capacitors, and 2 resistors.
“This is the first time that someone has shown graphene devices and circuits to perform modern wireless communication functions comparable to silicon technology,”
said Supratik Guha, Director of Physical Sciences at IBM Research. In a test the team successfully used the graphene-based receiver to process a digital transmission on 4.3GHz. The binary sequence received was 01001001 01000010 01001101, which represents ASCII coding of the letters IBM.
IBM Chip uses Graphene FETs - [Link]
Researchers from several institutions in the U.S. and one from China have together developed a piezoelectric device that when implanted in the body onto a constantly moving organ is able to produce enough electricity to run a pacemaker or other implantable device. In their paper published in Proceedings of the National Academy of Sciences, the team describes the nature of their device and how it might be used in the future.
Currently, when the battery inside a device such as a pacemaker runs out of power, patients must undergo surgery to have it replaced. Several devices that take advantage of the body’s natural parts have been devised to allow for the creation of electricity internally so that implantable devices can run for a lifetime, preventing the need for additional surgery. Most such devices have been too small to actually charge a real device, however, as they are very much still in the research stage. In this new effort, the research team takes the idea further by creating miniature power plants that are large enough to power real implantable devices.
Team builds implantable piezoelectric nanoribbon devices strong enough to power pacemaker - [Link]
A research team at Virginia Tech has produced a low-cost rechargeable battery that runs on sugar. They are not the first in the field to develop a sugar battery but the energy density of their design shows an order of magnitude improvement over existing sugar-based battery technology.
The findings from Y.H. Percival Zhang, an associate professor of biological systems engineering in the College of Agriculture and Life Sciences and the College of Engineering, were published in the journal Nature Communications. According to Zhang “Sugar is a perfect energy storage compound in nature, so it’s only logical that we try to harness this natural power in an environmentally friendly way to produce a battery”. [via]
Battery Recharging… One Lump or Two? - [Link]
Contactless charging of mobile devices is more convenient than fiddling around with power adapters, plugs and cables but the transmit and receive coils need to be in close physical contact otherwise power transfer losses become significant. A team of researchers in Duke’s Pratt School of Engineering working with the Toyota Research Institute of North America have succeeded in creating an array of hollow cubes which act as a lens for low-frequency magnetic fields.
The lens is made up of cells with copper coils etched onto their walls. The geometry of these coils and their repeating nature form a metamaterial that interacts with magnetic fields in such a way that the transmitted fields become confined into a narrow cone where the power intensity is much higher than that of an unfocussed pattern.
A Lens for Magnetic Fields - [Link]
The weak link in electric vehicle technology is the method of energy storage and renewal, making the vehicles impractical for long distance use. The majority of today’s electric vehicles use rechargeable lithium-ion batteries which still have a relatively poor energy density compared to conventional fossil fuels and require lengthy recharge cycles. A promising alternative battery chemistry is the lithium-sulfur battery. It can store as much as four times more energy per mass than lithium-ion batteries.
Unfortunately reactions at the battery’s sulfur-containing cathode form molecules called polysulfides that dissolve into the battery’s electrolyte. The dissolved sulfur eventually develops into a thin film called a solid-state electrolyte interface layer which coats the lithium-containing anode making the battery unusable after only 100 charge/discharge cycles.
Researchers at the US Department of Energy’s Pacific Northwest National Laboratory have succeeded in quadrupling the useful number of charge/discharge cycles. They have developed a graphite shield which moves the sulfur side reactions away from the anode’s lithium surface, preventing it from growing the debilitating interference layer. The new hybrid anode combines graphite from lithium-ion batteries with lithium from conventional lithium-sulfur batteries.
Graphite Boosts Battery Life - [Link]
Researchers experimenting with the properties of Graphene have discovered that when the single-atom-thick sheet is exposed to extreme low temperatures and high magnetic field it has the ability to filter electrons according to their spin direction.
At room temperature and with no magnetic field the flake of graphene functions as a normal conductor with electrons flowing throughout the sheet. With the application of a magnetic field perpendicular to the sheet the electrons migrate out to the sheet edges while the rest of the sheet has the properties of an insulator. Current flow around the edges is either clockwise or anticlockwise depending on the orientation of the field (known as the quantum Hall effect).
When the MIT researchers switched a second magnetic field in the same plane as the Graphene sheet they found that electrons move around the edge in either clockwise or counterclockwise direction depending on the electron’s direction of spin. [via]
Graphene could be good for Quantum Computing - [Link]
The Stanford University theoretical physicist Shoucheng Zhang and colleagues have suggested that a new material called Stanene, composed of a one-atom-thick sheet of tin, could act much like a room temperature superconductor.
Stanene is a type of topological insulator where the body of the material is an insulator but the surface and edges are electrically conductive. As electrons move around in the surfaces and edges of topological insulators, their spin axis aligns with their direction of flow. This effect (known as the quantum spin Hall state) means that electrons can’t easily reverse direction. In normal conductors when they hit an impurity they scatter and dissipate energy.
Although Stanene and superconductors can both exhibit zero resistance, Zhang emphasized that Stanene is not a superconductor. While the edges of Stanene act as a zero resistance path for electrons, they still encounter contact resistance at their junctions with normal conductors. In superconductors however, electrons travel in pairs, a phenomenon that eliminates contact resistance so that normal conductors effectively act like superconductors when in contact with a superconductor. [via]
Zero Resistance but not Superconducting? - [Link]
A team of Columbia Engineering researchers, led by Mechanical Engineering Professor James Hone and Electrical Engineering Professor Kenneth Shepard, exploring the properties of graphene have demonstrated a new electro-mechanical resonant component.
The resonator’s structure consists of a 2-4 micrometer long strip of graphene suspended over a metal gate electrode. The strip of graphene has a natural resonance governed by its physical dimension and is used in the demonstration as the frequency determining element in an RF feedback oscillator circuit. Applying a voltage to the gate electrode stresses and deflects the graphene strip changing its resonant frequency. The team applied baseband audio and tones to the gate electrode to produce a 100 MHz FM signal.[via]
Tiny FM Transmitter uses Voltage Controlled Graphene Resonator - [Link]