WCA November 2020

From the Americas of 98 per cent of infectious droplets. Now, researchers at Indiana University-Purdue University Indianapolis (IUPUI) Integrated Nanosystems Development Institute are examining an additional defence in the form of metallic copper oxide nanoparticles. Copper has long been known for germicidal and antimicrobial properties, and any virus that lands on a copper surface will be instantly disabled, so IUPUI’s Mangilal Agarwal described. He believes that many consumer-level masks, as opposed to clinical grade masks, have an insufficiently tight weave. A tighter weave, or the addition of other fabric layers, can make a mask uncomfortable to wear as well as making it harder for the wearer to breathe, and studies indicate that this has discouraged the wearing of masks when not a legal requirement. The IUPUI researchers suggest that embedded copper oxide nanoparticles add a kill layer; if droplets travel from one surface of the mask to another the copper will disable the virus en route. The team is now looking to use its findings to make lighter, stronger and cheaper composites with the ultimate aim of offering a wearable and safer alternative face mask for the general public. Mr Agarwal explained, “To make any fabric into a mask or filter we have to provide the nanostructure, and we can put that nanostructure on a roll-to-roll printing machine with the fibres at nanoscale. We are using electrospinning, using the electric field to spray the nanofibres on to the fabric.” Photonic integrated chip that promises new developments for optical technologies A new technology that can provide better light control, without needing large, difficult-to-integrate materials and structures, has been developed by researchers from Pennsylvania State University’s Materials Research Institute. The team believes that a new photonic integrated chip could pave the way for advances in the optical sector and industry, ranging from improvements in virtual reality glasses to optical remote sensing. Led by Xingjie Ni, a Charles H Fetter assistant professor of electrical engineering, the research was recently published in Science Advances . Four Penn State electrical engineering doctoral candidates, Xuexue Guo, Yimin Ding, Xi Chen and Yao Duan, were co-authors. To date, scientists have had two options when they need to control light for use in optical devices. The first is a photonic integrated circuit (PIC) that can be incorporated onto small chips, but has limited ability to control free-space light – light propagating in air, outer space or a vacuum, as opposed to being guided in fibres or other waveguides. The second option is a newly emergent metasurface – an artificially engineered thin layer that allows for light manipulation at sub-wavelength scale but cannot be integrated on a chip. Dr Ni and his fellow researchers believe they have solved this problem by incorporating the best qualities of both previous options into a new hybrid photonic architecture

that has metasurfaces integrated onto a PIC chip while maintaining high light controllability. “This incorporation of the PICs and metasurfaces makes it possible to drive the metasurfaces using guided waves inside the PICs,” explained Dr Ni. “It enables routing light among different metasurfaces, performing multiple complex functions on a single chip.” The new development could have applications in optical communications, optical remote sensing (LiDAR), free-space optical interconnects for data centres, and virtual reality and augmented reality displays. Dr Ni continued, “The developed technology will pave exciting ways for building multifunctional PIC devices, with flexible access to free space as well as guided, wave-driven metasurfaces with full on-chip integration capability.” For Dr Ni, among the most interesting features of his research are the implications for future developments and the success of combining the best traits of existing technology. “I think the most exciting part of the research is that we married two powerful technologies – integrated photonics and metasurfaces – with complementary capabilities,” he said. “Our hybrid system has the advantages from both the metasurfaces and the PICs. In addition, our design is highly flexible and modular; a library of the building blocks can be established for reusing and creating consistent functional components across various devices or systems.” Funding for the research came from the Gordon and Betty Moore Foundation, the National Aeronautics and Space Administration Early Career Faculty Award, the Office of Naval Research, and the Penn State Materials Research Science and Engineering Center. Study casts doubt on the reliability of driver-assistance technology Driver assistance technology that automates steering and braking is not providing reliable safety benefits, claims a new study from the American Automobile Association (AAA). Researchers at AAA, a federation of North American motor clubs, found that the systems are disrupted and disengaging typically every eight miles, frequently encountering situations they are not equipped to handle. The incidents create “dangerous situations if drivers rely too much on the technology, and stop paying attention to the road,” the AAA researchers said, adding that the systems are “far from 100 per cent reliable.” Greg Brannon, AAA’s director of automotive engineering and industry relations, said, “AAA has repeatedly found that active driving assistance systems do not perform consistently, especially in real-world scenarios.” Automakers are accelerating the automation of routine driving tasks such as highway cruising, or queueing in stop-and-start traffic. The automation options offer a new and needed source of profit for auto manufacturers and suppliers, as increasing numbers of consumers look to buy or lease vehicles with advanced driver assistance systems.

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Wire & Cable ASIA – November/December 2020

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