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EETE MAY 2015

3D-printing aerogels for energy storage By Paul Buckley Lawrence Livermore National Laboratory researchers have developed graphene aerogel micro-lattices with an engineered architecture by using a 3D printing technique known as direct ink writing. The 3D-printed aerogels will enable better energy storage, sensors, nanoelectronics, catalysis and separations. The research is reported in the April 22 edition of the journal, Nature Communications. The 3D printed graphene aerogels have high surface area, excellent electrical conductivity, are lightweight, have mechanical stiffness and exhibit super-compressibility (up to 90 percent compressive strain). In addition, the 3D printed graphene aerogel micro-lattices show an order of magnitude improvement compared with bulk graphene materials and much better mass transport. Aerogel is a synthetic porous, ultralight material derived from a gel, in which the liquid component of the gel has been replaced with a gas. Previous attempts at creating bulk graphene aerogels produced a largely random Lawrence Livermore researchers have made graphene aerogel micro-lattices with an engineered architecture via a 3D printing technique known as direct ink writing. (Photo by Ryan Chen/LLNL) pore structure, excluding the ability to tailor transport and other mechanical properties of the material for specific applications such as separations, flow batteries and pressure sensors. “Making graphene aerogels with tailored macro-architectures for specific applications with a controllable and scalable assembly method remains a significant challenge that we were able to tackle,” said engineer Marcus Worsley, a co-author of the paper. “3D printing allows one to intelligently design the pore structure of the aerogel, permitting control over mass transport (aerogels typically require high pressure gradients to drive mass transport through them due to small, tortuous pore structure) and optimization of physical properties, such as stiffness. This development should open up the design space for using aerogels in novel and creative applications.” During the process, the graphene oxide (GO) inks are prepared by combining an aqueous GO suspension and silica filler to form a homogenous, highly viscous ink. The GO inks are then loaded into a syringe barrel and extruded through a micro-nozzle to pattern 3D structures. “Adapting the 3D printing technique to aerogels makes it possible to fabricate countless complex aerogel architectures for applications such as mechanical properties and compressibility, which has never been achieved before, ” said engineer Cheng Zhu, the other co-author of the journal article. Foxconn linked to startup’s 52-Mpixel camera technology By Peter Clarke Imaging startup Light Co. (Palo Alto, Calif.) has revealed some details of its array camera approach and is reportedly close to announcing a licensing and investment deal with Hon Hai Precision Industries of Taiwan, better known as Foxconn. Light Co. was founded in 2013 as Tinz Optics Inc. but in 2014 benefited from a $9.7 million venture capital round that included Paul Jacobs, executive chairman of Qualcomm, and Sanjay Jha, CEO of Globalfoundries, among the investors. The main claim that Light is making is that it will allow smartphones to take photos even closer to digital SLR quality. Even though it is still at a pre-prototype stage it has reportedly said it expects the first light cameras to appear in smartphones in 2016 with the 52-megapixel resolution. Light’s approach is similar to that of array camera pioneers such as Pelican Imaging Corp. and LinX Computational Imaging Ltd. However, Light does not restrict itself to an array of identical sensors but uses multiple sensors with lens set at different fixed focal lengths so that it can simulate a zoom lens after a photo has been taken. It can still use computational effects after a photo has been taken – in reality a series of photos – to get enhanced resolution similar to other plenoptic approaches. And to help that happen Light has received backing from Foxconn, the world’s largest contract manufacturer of electronics. In addition Foxconn will be licensing Light’s technology for use in mobile devices. “The system will enable people to easily carry a small, single device that offers true optical zoom with no protruding elements – we are currently prototyping 35mm-150mm – capture lownoise images even in low-light situations, and control depth-of-field and focus as part of the editing process,” Laroia told a publication called the Daily Dot. One limitation is that Light’s approach still requires a reasonable z height to accommodate its array of cameras, about the same as is used by smartphones today according to a Massachusetts Institute of Technology Review article. That would count against the technology for smartphone vendors who want to go even thinner. And the technology is being pitched as a premium product with a cost to equipment makers of $60 to $80. That compares to $3 to $5 for a low-end camera for an entry-level phone and $20 to $25 for cameras in smartphones. 6 Electronic Engineering Times Europe May 2015 www.electronics-eetimes.com


EETE MAY 2015
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