CTT-other mat stories

CTT-other mat stories

Ultra-thin carbon-based wafer saws save silicon

You can’t saw without producing sawdust, and that can be expensive if, for example, you’re sawing silicon wafers for photovoltaic and semiconductor applications. But scientists from the Fraunhofer Institute for Mechanics of Materials IWM (Freiburg, Germany) and the Australian Commonwealth Scientific and Industrial Research Organisation (CSIRO; Highett, Victoria) have developed an ultra-thin saw made of diamond-coated carbon nanotubes. The saws are produced from ultra-thin carbon nanotube“felt” that is twisted into a yarn 10–20 μm in diameter. The nanotube substrate is then coated with silica to protect it from the hydrogen atmosphere and 900°C temperatures needed for diamond deposition. The researchers have filed a joint patent application for the manufacturing method and corresponding products, and are testing the ultra-thin saws.

Slippery coating for glass

A new transparent, bioinspired coating makes ordinary glass tough, self-cleaning, and incredibly slippery, a team from the Wyss Institute for Biologically Inspired Engineering at Harvard University and Harvard School of Engineering and Applied Sciences (SEAS) recently reported. The material builds on a technology the team pioneered called slippery liquid-infused porous surfaces, which is said to be the slipperiest synthetic surface known. The new coating is equally slippery but more durable and fully transparent, and could be used to create durable, scratch-resistant lenses for eyeglasses, self-cleaning windows, improved solar panels, and new medical diagnostic devices, the researchers say.

Zinc oxide nanowires act as piezo-phototronic LEDs

Using thousands of nanometer-scale zinc oxide wires, researchers at Georgia Institute of Technology have developed a sensor device that converts mechanical pressure from a signature or a fingerprint directly into light signals that can be captured and processed optically. The sensor device could provide an artificial sense of touch, offering sensitivity comparable to that of the human skin, or be used in biological imaging and micro-electromechanical systems. Individual zinc oxide nanowires in the device operate as tiny LEDs when placed under strain from mechanical pressure, allowing the device to provide detailed information about the amount of pressure being applied with resolution of up to 6,300 dots per inch.


Graphene supercapacitors near commercialization

Researchers at Monash University (Victoria, Australia) have developed a graphene-based supercapacitor said to be applicable to renewable energy storage, portable electronics, and electric vehicles. Supercapacitors are generally made of porous carbon impregnated with a liquid electrolyte to transport the electrical charge. Such devices typically have energy density of 5–8 W-hr/L, which means they must be either very large or recharged frequently. The researchers say their graphene-based supercapacitor has energy density of 60 W-hr/L—comparable to lead-acid batteries. The scientists used an adaptive graphene gel film they had developed previously and liquid electrolytes to control the spacing between graphene sheets on the subnanometer scale. The advancement is said to be near the stage of moving from the lab to commercial development.

Bubbles are the new lenses for nanoscale light beams

Bending light beams using a few tiny liquid bubbles may be all that is necessary to open the doors for next-generation, high-speed circuits and displays, according to Penn State researchers. To combine the speed of optical communication with the portability of electronic circuitry, researchers use nanoplasmonics—devices that use short electromagnetic waves to modulate light on the nanometer scale, where conventional optics do not work. However, aiming and focusing this modulated light beam at desired targets is difficult. The main advantage of a bubble lens is just how quickly and easily researchers can reconfigure the bubble’s location, size, and shape, all of which affect the direction and focus of any light beam passing through it.  A research team created separate simulations of the light beams and bubble lens to predict their behaviors and optimize conditions before combining the two in the laboratory. To form the bubble lens, researchers used a low-intensity laser to heat water on a gold surface. The tiny bubble’s optical behavior remains consistent as long as the laser’s power and the environmental temperature stay constant.