TechFront: New Laser-Like Polariton Beams Show Promise for Electronics, Medical Uses
Researchers at the University of Michigan (Ann Arbor, MI) have developed a new laser-like beam, called a polariton, that is said to be the first polariton laser powered by electrical current instead of light. The invention, which technically isn’t a laser, also works at room temperature instead of at below-zero temperatures.
The device is said to be the most ready for real-world applications of the polariton lasers that have been developed to date. This work could advance research into using lasers on computer chips to replace wire connections, leading to smaller and more powerful electronics. It also may be useful in medical devices and treatments.
“This is big. For the past 50 years, we have relied on lasers to make coherent light and now we have something else based on a totally new principle,” said Pallab Bhattacharya, the Charles M. Vest Distinguished University Professor of Electrical Engineering and Computer Science and the James R. Mellor Professor of Engineering at U-M.
The research team’s findings are described in the paper, “Room Temperature Electrically Injected Polariton Laser,” published online June 10 in the journal Physical Review Letters. The work was funded by the National Science Foundation.
A polariton is part light and part matter, and polariton lasers harness these particles to emit light. These laser-like beams are predicted to be much more energy-efficient than traditional lasers, and the U-M researchers noted the new prototype requires 250 times less electricity to operate than its conventional counterpart made of the same material.
The researchers didn’t develop it with a specific use in mind. Bhattacharya’s system isn’t technically a laser, which is an acronym for Light Amplification by Stimulated Emission of Radiation. The polariton lasers don’t stimulate radiation emission but instead stimulate scattering of polaritons. With a typical laser, light or more often electrical current, is pumped into a material, called a gain medium, that’s designed to amplify the signal. Before the pumping begins, most of the electrons in the gain medium are in their least energetic state, also known as the ground state. Once the light or current hits them, the electrons absorb that energy and move to a higher-energy state. At some point, more electrons are high-energy than are low-energy and the device is said to have achieved a “population inversion.”
Polariton lasers don’t rely on these population inversions, so they don’t need a lot of start-up energy to excite electrons and then knock them back down. “The threshold current can be very small, which is an extremely attractive feature,” Bhattacharya said. He and his team paired the right material—the hard, transparent semiconductor gallium nitride—with a unique design to maintain the controlled circumstances that encourage polaritons to form and then emit light.
The beam demonstrated by the research team was ultraviolet, and very low power, less than a millionth of a watt. Lasers in a CD player are about one-thousandth of a watt. For more information, see www.umich.edu. ME
Tough, Ultralight Graphene Oxide Foam
A team of researchers at Rice University (Houston) have created a tough, ultralight foam material that could find use in structural components and as supercapacitor and battery electrodes, and for gas absorption, among other applications.
The foam is called GO-0.5BN, and it has the appearance of a nanoscale building in microstructural images. The graphene oxide (GO) material is like graphene, with a hexagonal lattice of carbon atoms that offers superior strength and conductivity.
This research involved an international group of researchers led by the Rice lab materials scientist Pulickel Ajayan. It appeared July 29 in the online journal Nature Communications.
Adding hexagonal boron nitride (h-BN) to graphene oxide toughened the resulting foam, as expected by the team of researchers, said Soumya Vinod, the Rice graduate student who co-led the project.
Those properties include the ability to handle a great deal of strain and still bounce back to its native form. Vinod said that this is remarkable for a material so light that a stray breath in the lab would send the small samples flying.
The components of the new material start as cheap, plentiful powders, and atom-thick layers of graphene oxide and h-BN are chemically exfoliated from the powders, mixed in the proper proportion with a few chemical catalysts and freeze-dried. The resulting foam takes the shape of the container and is 400 times less dense than graphite. ME
Back to the Future of Robotics and Automation
As subjects of SME’s ongoing attention for decades, automation was discussed as early as 1953 and robot-like machines were described long before the actual word “robots” was used in a paper title in 1973. Hundreds of technical papers were written for the ISIR (International Symposium on Industrial Robots) and ROBOTS series of events and for numerous automated factory (AUTOFACT), assembly, machine vision, finishing and material handling conferences.
In all, more than 600 papers fit these categories. In addition, content from SME’s magazines, research conferences, reference books and videos/DVDs completes a solid body of knowledge on these industry-transforming themes. Authors hail from well-known industrial names (some gone, but not forgotten) and distinguished institutions, such as Otis, Westinghouse, Ford, General Electric, Northrop Grumman, Cincinnati Milacron, Steelcase, Honeywell, Chrysler, Deere, Rockwell, Sandia, Lawrence Livermore, Georgia Tech, General Motors Institute, FANUC, Prab and Unimation.
“Automation and the Good Life” (paper number TP62PUB65) was Alfred V. Bodine’s lecture as the recipient of the 1962 SME Eli Whitney Productivity Award. The ingenious ways developed to make separate items flow through production processes have raised the US standard of living and continue to be “inextricably tied up with our urgent need to increase productivity,” Bodine concluded.
Periodically, papers overview the role of automation and, later, robotics: TP58PUB124—“automation is needed to meet our projected national growth,” TP78PUB230—“more sophisticated automation systems to integrate robots into the manufacturing process,” TP82PUB189—“the robotics industry is impacting the machine tool industry in much the same way NC machines did many years ago” and TP83PUB271—“the transition from an industrial to an information society and the changing nature of work.”
Even before SME’s former Robotics Today magazine debuted in 1979 to report on the “widening niche (robots) are finding in many branches of industry,” SME Tech Papers covered applications and lessons learned in robotic welding, forming, molding, painting, finishing, drilling and deburring. Robotic skills training, more complex applications, and research and analysis of robot structures and controls were added to the mix over the years.
Medical and Military
The implementation of a production robotic system in the pacemaker industry is described in TP85PUB442, an active end-effector for a surgical robot used in craniofacial surgery is the work of German researchers (TP04PUB200) and “deformable robots,” which require a nonpenetrating, collision-free path for the complex and sensitive environments of minimally invasive surgery and treatment, are detailed in TP06PUB30.
Automated machining of custom anatomical models for orthopedic and plastic surgeons are featured in TP85PUB815. In the pharmaceutical industry, automation advances in medical apparatus, instruments, medicines, solutions and the means to administer to the sick include computerized medical information systems, blood bank inventories and simulated disasters (TP68PUB263).
The US Army’s efforts—known as the SCAMP program—to bring small caliber ammunition production up to date from the World War II era are detailed in TP73PUB288. Other papers cover ordnance assembly and inspection (TP67PUB104 and TP67PUB169) and production improvements with robotics (TP84PUB455 and TP86PUB816).
Food and Fashion
A team from a university, a robotic motion control company and a pork processing plant developed a high-speed, low-cost robotic case packer to address the needs of food processing companies (TP05PUB204). Other food applications include automated inspection of glass food jars (TP85PUB494) and automatic computer control in the wine industry (TP86PUB564).
Convenience packaging (soda cans, cereal boxes, milk cartons), with ever-changing designs to “offer both eye appeal and product delight” to consumers, benefits from automation to maximize cost-savings and productivity (TP71PUB285).
What we wear and walk on is covered, too, in robotics research and development in the garment industry (TP86PUB554) and automated yarn creeling for fabric and carpet manufacture (TP98PUB86). Robots in furniture finishing take on very dirty jobs with high labor turnover (TP75PUB319). ME
TechFront is edited by Senior Editors Patrick Waurzyniak email@example.com and Ellen Kehoe firstname.lastname@example.org.
All SME Technical Papers are available by entering the paper number or a keyword in the search box at http://tinyurl.com/searchsme.
This article was first published in the September 2014 edition of Manufacturing Engineering magazine. Click here for PDF.
Published Date : 9/1/2014