Capturing wasted heat to power devices
Imagine how much you could save on your electricity bill if you could use the excess heat your computer generates to actually power the machine. Towards this end, researchers at the UCLA Henry Samueli School of Engineering and Applied Science have taken an important step toward harnessing that heat and converting it for practical use, which could lead to more energy-efficient appliances and information processing devices.
The research team has demonstrated how to add power to a spintronics device, which uses the spin of electrons for energy rather than their charge. Excess heat, like that generated by extended use of a computer or other device, naturally creates what is known as a spin wave that can move a domain wall. A domain wall separates magnetic materials that point in different directions in certain magnetic devices.
According to the researchers, if housed within the central processing unit of a computer or other electrical device, a domain wall would serve as a sort of turbine, capturing the heat from the traveling spin wave and converting it into energy, just as a turbine harnesses the power of water and converts it into electrical energy that can be used to redirect the water or serve another purpose. The captured energy can then be used to help power the electrical device.
The concept of using heat energy to move magnetic domain walls is not new, they said, but this paper is the first demonstration of moving a domain wall through propagation of a spin wave.
The capture of heat energy could serve to supplement the power provided by traditional CMOS circuits in devices from smartphones to computer servers and large electrical equipment. In the long run, the researchers expect the process to serve as an alternative to CMOS circuits in many devices.
‘Super-resolution’ microscope to view nanostructures
Purdue University researchers have found a way to see synthetic nanostructures and molecules using a new type of super-resolution optical microscopy that does not require fluorescent dyes, representing a practical tool for biomedical and nanotechnology research.
Conventional optical microscopes can resolve objects no smaller than about 300 nanometers, or billionths of a meter, a restriction known as the “diffraction limit,” which is defined as half the width of the wavelength of light being used to view the specimen. However, researchers want to view molecules such as proteins and lipids, as well as synthetic nanostructures like nanotubes, which are a few nanometers in diameter.
Such a capability could bring advances in a diverse range of disciplines, from medicine to nanoelectronics. The diffraction limit represents the fundamental limit of optical imaging resolution. Super-resolution imaging methods have been developed that require fluorescent labels but here the researchers demonstrate a new scheme for breaking the diffraction limit in optical imaging of non-fluorescent species. Because it is label-free, the signal is directly from the object so that we can learn more about the nanostructure.
The imaging system, called saturated transient absorption microscopy (STAM) uses a trio of laser beams, including a doughnut-shaped laser beam that selectively illuminates some molecules but not others. Electrons in the atoms of illuminated molecules are kicked temporarily into a higher energy level and are said to be excited, while the others remain in their “ground state.” Images are generated using a laser called a probe to compare the contrast between the excited and ground-state molecules.
The researchers demonstrated the technique, taking images of graphite “nanoplatelets” about 100 nanometers wide.
Low-cost, long-life battery
Researchers from the U.S. Department of Energy’s (DOE) SLAC National Accelerator Laboratory and Stanford University have designed a low-cost, long-life battery that they believe could enable solar and wind energy to become major suppliers to the electrical grid.
For solar and wind power to be used in a significant way, a battery is needed that is made of economical materials that are easy to scale and still efficient. The researchers believe their new battery may be the best yet designed to regulate the natural fluctuations of these alternative energies.
Currently the electrical grid cannot tolerate large and sudden power fluctuations caused by wide swings in sunlight and wind. As solar and wind’s combined contributions to an electrical grid approach 20 percent, energy storage systems must be available to smooth out the peaks and valleys of this “intermittent” power – storing excess energy and discharging when input drops.
Among the most promising batteries for intermittent grid storage today are “flow” batteries, because it’s relatively simple to scale their tanks, pumps and pipes to the sizes needed to handle large capacities of energy. The new flow battery developed by the Stanford group has a simplified, less expensive design that presents a potentially viable solution for large-scale production.
~Ann Steffora Mutschler