Category Archives: light

Unique ‘printing’ process boosts supercapacitor performance

In addition to creating energy, we also need to store some of it for future use as a July 29, 2013 news release from the University of Central Florida notes,

Researchers at the University of Central Florida have developed a technique to increase the energy storage capabilities of supercapacitors, essential devices for powering high-speed trains, electric cars, and the emergency doors of the Airbus A380.

The finding, which offers a solution to a problem that has plagued the growing multi-billion dollar industry, utilizes a unique three-step process to “print” large – area nanostructured electrodes, structures necessary to improve electrical conductivity and boost performance of the supercapacitor.

Jayan Thomas, an assistant professor in UCF’s NanoScience Technology Center, led the project which is featured in the June edition of Advanced Materials, one of the leading peer-reviewed scientific journals covering materials science in the world. Thomas’ research appears on the journal’s highly-coveted frontispiece, the illustration page of the journal that precedes the title page.

The news release goes on to describe the supercapacitor issue the researchers were addressing,

Supercapacitors have been around since the 1960’s. Similar to batteries, they store energy. The difference is that supercapacitors can provide higher amounts of power for shorter periods of time, making them very useful for heavy machinery and other applications that require large amounts of energy to start.  However, due to their innate low energy density; supercapacitors are limited in the amount of energy that they can store.

“We had been looking at techniques to print nanostructures,” said Thomas. “Using a simple spin-on nanoprinting (SNAP) technique, we can print highly-ordered nanopillars without the need for complicated development processes. By eliminating these processes, it allows multiple imprints to be made on the same substrate in close proximity.“

This simplified fabrication method devised by Thomas and his team is very attractive for the next-generation of energy storage systems. “What we’ve found is by adding the printed ordered nanostructures to supercapacitor electrodes, we can increase their surface area many times,” added Thomas. “We discovered that supercapacitors made using the SNAP technique can store much more energy than ones made without.”

Here’s a link to and a citation for the research paper abut this new technique for supercapacitors,

Energy Storage: Highly Ordered MnO2 Nanopillars for Enhanced Supercapacitor Performance (Adv. Mater. 24/2013) by Zenan Yu, Binh Duong, Danielle Abbitt, and Jayan Thomas. Article first published online: 20 JUN 2013 DOI: 10.1002/adma.201370160 Advanced Materials Volume 25, Issue 24, page 3301, June 25, 2013.

Lead researcher Thomas was recently featured in a video for his work on creating plasmonic nanocrystals from gold nanoparticles (from the news release),

Thomas, who is also affiliated with the College of Optics and Photonics (CREOL), and the College of Engineering, was recently featured on American Institute of Physics’ Inside Science TV for his collaborative research to develop a new material using nanotechnology that could potentially help keep pilots safe by diffusing harmful laser light.

Here’s the video,

You can find videos, news, and blogs featuring other research at Inside Science and you can find out more about Dr. Jayan Thomas here.

Fireflies and their jagged scales lead to brighter LEDs (light emitting diodes)

According to the Jan. 8, 2013 news item on ScienceDaily, scientists have used an observation about fireflies to make brighter LEDs (light emitting diodes),

The nighttime twinkling of fireflies has inspired scientists to modify a light-emitting diode (LED) so it is more than one and a half times as efficient as the original.

Researchers from Belgium, France, and Canada studied the internal structure of firefly lanterns, the organs on the bioluminescent insects’ abdomens that flash to attract mates. The scientists identified an unexpected pattern of jagged scales that enhanced the lanterns’ glow, and applied that knowledge to LED design to create an LED overlayer that mimicked the natural structure. The overlayer, which increased LED light extraction by up to 55 percent, could be easily tailored to existing diode designs to help humans light up the night while using less energy.

The Optical Society of America’s Jan. 8, 2013 news release, which originated the news item, describes how the scientists came to make their observations,

“The most important aspect of this work is that it shows how much we can learn by carefully observing nature,” says Annick Bay, a Ph.D. student at the University of Namur in Belgium who studies natural photonic structures, including beetle scales and butterfly wings.  When her advisor, Jean Pol Vigneron, visited Central America to conduct field work on the Panamanian tortoise beetle (Charidotella egregia), he also noticed clouds of twinkling fireflies and brought some specimens back to the lab to examine in more detail.

Fireflies create light through a chemical reaction that takes place in specialized cells called photocytes. The light is emitted through a part of the insect’s exoskeleton called the cuticle.  Light travels through the cuticle more slowly than it travels through air, and the mismatch means a proportion of the light is reflected back into the lantern, dimming the glow. The unique surface geometry of some fireflies’ cuticles, however, can help minimize internal reflections, meaning more light escapes to reach the eyes of potential firefly suitors.

In Optics Express papers, Bay, Vigneron, and colleagues first describe the intricate structures they saw when they examined firefly lanterns and then present how the same features could enhance LED design. Using scanning electron microscopes, the researchers identified structures such as nanoscale ribs and larger, misfit scales, on the fireflies’ cuticles. When the researchers used computer simulations to model how the structures affected light transmission they found that the sharp edges of the jagged, misfit scales let out the most light. The finding was confirmed experimentally when the researchers observed the edges glowing the brightest when the cuticle was illuminated from below.

“We refer to the edge structures as having a factory roof shape,” says Bay.  “The tips of the scales protrude and have a tilted slope, like a factory roof.” The protrusions repeat approximately every 10 micrometers, with a height of approximately 3 micrometers. “In the beginning we thought smaller nanoscale structures would be most important, but surprisingly in the end we found the structure that was the most effective in improving light extraction was this big-scale structure,” says Bay.

Here’s how the scientists applied their observations to LEDs (from the news release),

Human-made light-emitting devices like LEDs face the same internal reflection problems as fireflies’ lanterns and Bay and her colleagues thought a factory roof-shaped coating could make LEDs brighter. In the second Optics Express paper published today, which is included in the Energy Express  section of the journal, the researchers describe the method they used to create a jagged overlayer on top of a standard gallium nitride LED. Nicolas André, a postdoctoral researcher at the University of Sherbrooke in Canada, deposited a layer of light-sensitive material on top of the LEDs and then exposed sections with a laser to create the triangular factory-roof profile. Since the LEDs were made from a material that slowed light even more than the fireflies’ cuticle, the scientists adjusted the dimensions of the protrusions to a height and width of 5 micrometers to maximize the light extraction.

“What’s nice about our technique is that it’s an easy process and we don’t have to create new LEDs,” says Bay.  “With a few more steps we can coat and laser pattern an existing LED.”

Other research groups have studied the photonic structures in firefly lanterns as well, and have even mimicked some of the structures to enhance light extraction in LEDs, but their work focused on nanoscale features. The Belgium-led team is the first to identify micrometer-scale photonic features, which are larger than the wavelength of visible light, but which surprisingly improved light extraction better than the smaller nanoscale features. The factory roof coating that the researchers tested increased light extraction by more than 50 percent, a significantly higher percentage than other biomimicry approaches have achieved to date. The researchers speculate that, with achievable modifications to current manufacturing techniques, it should be possible to apply these novel design enhancements to current LED production within the next few years.

For those who care to investigate further,

Both articles (HTML version) are open access; PDF versions were not checked.

Lumerical’s latest INTERCONNECT product and statistic variations in one or more circuit elements

Vancouver- (Canada) based Lumerical Solutions’ Sept. 12, 2012 (?) product announcement for its INTERCONNECT 2.0 release notes some improvements and new features,

Release 2.0 of INTERCONNECT enables PIC designers to more quickly explore the role of circuit architecture and statistical component variations on overall circuit performance.  New features include an improved frequency-domain calculation engine which can compute circuit performance significantly faster, a custom s-parameter element which can accept measured or simulated data of arbitrary complexity including complete characterization data for multimode, many-port elements, and a yield calculator that produces Monte Carlo performance estimates based on statistical variations of one or more circuit parameters.

As the company seems to do on a regular basis, they are offering a free 30-day evaluation period for the product.

The Sept. 12, 2012 product announcement offers some insight into which users might find this product most useful along with some testimonials from the product’s current users,

INTERCONNECT has been engineered, since the original product concept, to support both device and circuit designers.  Device designers are interested in component dimensions and material compositions, often with the goal of designing new proprietary circuit elements that work well with adjacent components.  Circuit designers are focused on achieving desired target performance and are often only interested in using element-level transfer functions and compact models to predict system behavior. INTERCONNECT 2.0’s yield calculator, which accepts statistical variations at the element level whether they apply to physical or phenomenological parameters, continues to support both designer profiles.

Professor Lukas Chrostowski of the University of British Columbia, and Director of the NSERC [Natural Sciences and Engineering Research Council] CREATE Si-EPIC training program, believes that device designers will benefit from INTERCONNECT’s integration with MODE Solutions and FDTD Solutions.  “The software can be used to design devices such as ring resonators, waveguide Bragg gratings, arrayed waveguide gratings, and fibre grating couplers, and to study the performance of components within simple circuits,” he said.  “For example, reflections from components such as grating couplers often introduce undesired ripple in the optical spectrum, and this can be simulated using INTERCONNECT.”

As photonic integrated circuits are complex and require multi-physics simulation, the ability to create hierarchically-defined elements from single devices like a modulator to entire transmitter subsystems is very important.  Being able to experimentally verify these devices and subsystems and incorporate that data into a single design environment together with statistical variations at every level of the design hierarchy promises to streamline the design process.

“In response to ongoing requests for a framework that goes beyond idealized representations, INTERCONNECT 2.0 can incorporate statistical variations of geometrical or compact-model parameters,” according to Dr. Jackson Klein, Senior Product Manager of INTERCONNECT. “Together with INTERCONNECT’s hierarchical model definition, proprietary component-level IP can be easily incorporated into more sophisticated circuit models of arbitrary complexity.”

INTERCONNECT’s ability to model multimode, many-port circuits of arbitrary complexity and physical sophistication means it will play a critical role as designers explore circuit designs incorporating proprietary elements and ever-increasing component count.  “We look forward to our ongoing discussions with industry and foundry representatives, public and private companies, and government laboratories to refine INTERCONNECT’s capabilities so that it can best serve the emerging needs of the photonic integrated circuit design community,” says Dr. James Pond, Lumerical’s Chief Technology Officer.

University of Delaware Professor and Director of OpSIS Michael Hochberg has extensive experience working with Lumerical.  “We’re very happy with their tools and investment in the INTERCONNECT product,” he said.  “At OpSIS, our goal is to provide to anyone in the world with advanced silicon photonics processes for their own projects, while only paying for the wafer area that they use.  Doing schematic-driven design is really critical for making complex photonic circuits, and to make it easy for our users to lay out and simulate systems-on-chip we are now working with Lumerical to integrate OpSIS device libraries with their tools.”

The company has been quite active lately, the last product announcement was mentioned in my July 6, 2012 posting about Lumerical’s FDTD solution.

Vancouver (Canada)-based company, Lumerical Solutions, files patent on new optoelectronic simulation software

I’m not a huge *fan of patents as per various postings (my Oct. 31, 2011 posting is probably my most overt statement) so I’m not entirely thrilled about this news from Lumerical Solutions, Inc. According to the June 14, 2012 news item on Nanowerk,

Lumerical Solutions, Inc., a global provider of optoelectronic design software, announced the filing of a provisional patent application titled, “System and Method for Transforming a Coordinate System to Simulate an Anisotropic Medium.” The patent application, filed with the US Patent and Trademark Office, describes how the optical response of dispersive, spatially varying anisotropic media can be efficiently simulated on a discretized grid like that employed by finite-difference time-domain (FDTD) or finite-element method (FEM) simulators. The invention disclosed is relevant to a wide array of applications including liquid crystal display (LCD) panels, microdisplays, spatial light modulators, integrated components using liquid crystal on silicon (LCOS) technology like LCOS optical switches, and magneto-optical elements in optical communication and sensing systems.

The company’s June 14, 2012 news release includes this comment from the founder and Chief Technical Office (CTO),

According to Dr. James Pond, the inventor and Lumerical’s Chief Technology Officer, “many next generation opto-electronic products combine complicated materials and nano-scale structure, which is beyond the capabilities of existing simulation tools. Lumerical’s enhanced framework allows designers to accurately simulate everything from liquid crystal displays to OLEDs, and silicon photonics to integrated quantum computing components.”

Lumerical’s new methodology for efficiently simulating anisotropic media is part of a larger effort to allow designers the ability to model the optical response of many different types of materials.  In addition to the disclosed invention, Lumerical has added a material plugin capability which will enable external parties to include complicated material models, such as those required for modelling semiconductor lasers or non-linear optical devices, into FDTD-based simulation projects.

…  According to Chris Koo, an engineer with Samsung, “Lumerical’s latest innovation has established them as the clear leader in the field of optoelectronic device modeling.  Their comprehensive material modeling capabilities paves the way for the development of exciting new technologies.”

I wish the company good luck. Despite my reservations about current patent regimes, I do appreciate that in some situations, it’s best to apply for a patent.

For the curious, here’s a little more (from the company’s About Lumerical page),

By empowering research and product development professionals with high performance optical design software that leverages recent advances in computing technology, Lumerical helps optical designers tackle challenging design goals and meet strict deadlines. Lumerical’s design software solutions are employed in more than 30 countries by global technology leaders like Agilent, ASML, Bosch, Canon, Harris, Northrop Grumman, Olympus, Philips, Samsung, and STMicroelectronics, and prominent research institutions including Caltech, Harvard, Max Planck Institute, MIT, NIST and the Chinese Academy of Sciences.

Our Name

Lu.min.ous (loo’me-nes) adj., full of light, illuminated

Nu.mer.i.cal (noo-mer’i-kel) adj., of or relating to a number or series of numbers

Lu.mer.i.cal (loo-mer’i-kel) – A company that delivers inventive, highly accurate and cost effective design solutions resulting in significant improvements in product development costs and speed-to-market.

* June 15, 2012: I found the error this morning (9:20 am PDT) and added the word ‘fan’.

Happy Canada Day!

This will be a short one. My recent paper, ‘Nanotechnology, storytelling, sensing, and materiality‘, gave me a chance to explore the impact that various sensing technologies used for the nanoscale might have on storytelling. In one of those happy coincidences that can occur, I came across a new sensing technique (although strictly speaking it’s not applied at the nanoscale) that incorporates light and sound on Nanowerk News here. The new technique has allowed researchers to create three-dimensional whole body visualizations of zebra fish. From Nanowerk News,

The real power of the technique, however, lies in specially developed mathematical formulas used to analyze the resulting acoustic patterns. An attached computer uses these formulas to evaluate and interpret the specific distortions caused by scales, muscles, bones and internal organs to generate a three-dimensional image. The result of this “multi-spectral opto-acoustic tomography”, or MSOT, is an image with a striking spatial resolution better than 40 micrometers (four hundredths of a millimeter). And best of all, the sedated fish wakes up and recovers without harm following the procedure.

This new technique, MSOT, has applications for medical research.

In tangentially related news, Rob Annan’s posting on the ‘Don’t leave Canada behind‘ blog (June 30, 2009) features a few comments about a recent article in the New York Times that suggests current funding structures inhibit innovative cancer research. The report was written about US funding but Annan offers some thoughts on the matter and points the way to more Canadian commentary as well as the New York Times article.

That’s it. Happy Canada Day.

New international nanotechnology safety study and a Canadian synchrotron conference

There’s a new report on nanotechnology safety studies, the ‘EMERGNANO report‘. The researchers surveyed environment, health, and safety studies internationally, determined which ones fit their criteria, and have  now provided an assessment of the findings. Short story: there are no conclusive findings which is troublesome given the number of nanomaterial-based products that are making their way into the international marketplace. Michael Berger on Nanowerk News offers an excellent assessment of the situation vis a vis technophobic and technophilic approaches to emerging technologies and their attendant safety issues,New technologies are always polarizing society – some only see the inherent dangers, others only see the opportunities. Since these two groups usually are the loudest, everybody else inbetween has a hard time to get their message across and with objective information and facts. Nanotechnologies are no different. The nay-sayers call for a total moratorium everytime scientific research with concerning conclusions is published while opportunistic hypsters are only interested in selling more products or reports and ridicule even the faintest objections and concerns as uninformed panicmongering.

For more, please go here. I notice that Andrew Maynard (mentioned frequently here due to his 2020 Science blog and his position as Chief Science Advisor for the Project on Emerging Nanotechnologies) is one of the authors.

There’s a nanotechnology-type conference being held in Saskatoon, Saskatchewan, Canada this week (June 17 – 18, 2009). They have a big synchroton facility there and, I believe, it is the only such facility in Canada, which according to their video, is one of the most advanced such facilities in the world. The 12th annual meeting features a public lecture, ‘Science Fiction as a Mirror for Reality‘, by  Robert J. Sawyer, an internationally renowned Canadian science fiction author. For details about the conference,go here. For information about the synchroton in Saskatoon, go here. For information about Robert J. Sawyer, go here. (Media release noting the event can be found on Nanowerk News.)