Plasmonic device converts light into electricity

By Lisa Zyga

Surface plasmons on the top electrode in the MIM device can increase the current from the top electrode so that it is greater than the current from the bottom electrode, generating a positive net current. Image credit: Wang and Melosh. ©2011 American Chemical Society

While the most common device for converting light into electricity may be photovoltaic (PV) solar cells, a variety of other devices can perform the same light-to-electricity conversion, such as solar-thermal collectors and rectennas. In a new study, engineers have designed a new device that can convert light of infrared (IR) and visible wavelengths into direct current by using surface plasmon excitations in a simple metal-insulator-metal (MIM) device.

The researchers, Fuming Wang and Nicholas A. Melosh of Stanford University, have published their study on the new device in a recent issue of Nano Letters. “The greatest significance thus far is to show an alternative method to rectennas and PV devices for IR and visible light conversion,” Melosh told PhysOrg.com. “The conversion efficiencies aren't amazingly high compared to a PV in visible, so it’s not going to replace PVs, but it could be used for energy scavenging later on.” The new device’s MIM architecture is similar to that of a rectenna. However, whereas rectennas operate with long-wavelength light such as microwaves and radio waves, the new device operates with a broad spectrum of infrared to visible wavelengths. When the MIM device is illuminated, incoming photons are absorbed by the top and bottom metal electrodes. Upon absorption, each photon excites an electron in the metal into a higher energy state so that it becomes a “hot electron.” About half of the hot electrons travel toward the metal-insulator interface, where they may be collected by the other electrode. However, photon absorption in the upper and lower electrodes generates currents with opposite signs, so a net DC current is achieved only if the absorption is larger at one electrode than the other.

Electron transmission in MIM devices (a) with and (b) without surface plasmon excitations. (c) The measured photocurrent in a device with surface plasmons (black line) is higher than in a device without them (red line). Image credit: Wang and Melosh. ©2011 American Chemical Society

This ability to maximize current from one electrode while minimizing it from the other is one of the biggest challenges for MIM devices. To do this, researchers can change the thicknesses of the electrodes. However, there is a tradeoff, since in a thicker electrode, more photons are absorbed but fewer electrons reach the interface due to increased scattering. Wang and Melosh’s solution is to use a prism to excite surface plamons (SPs) on the metal surface of the electrodes when under illumination. The SPs, which are small electron oscillations, can create a higher concentration of hot electrons in one electrode by efficiently coupling to light. The SP coupling efficiency depends on several factors, such as the thickness of the electrode, the type of metal used, and the wavelength of incoming light.

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Plasmonic device converts light into electricity
More information: Fuming Wang and Nicholas A. Melosh. “Plasmonic Energy Collection through Hot Carrier Extraction.” Nano Letters, DOI: 10.1021/nl203196z

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Don't Innovate, Imitate

By Jonathan Moules

Imitation is not just the sincerest form of flattery. It is one of the shrewdest ways to become a successful entrepreneur.

Entrepreneurs are often mistaken for inventors. They are not.
There are some very entrepreneurial inventors, but they are an exception. Most entrepreneurs take another person's technological breakthrough and use their skills in mobilizing resources, publicity, salesmanship, and financial management to create a viable business.

Inventors create the technology, but entrepreneurs turn it into something of economic value. It is possible to go a stage further than this, however, because people do not just invent things, such as cars or personal computers, they come up with ideas for new services that people need and ways of providing them.

Many successful entrepreneurs have built great businesses by doing what someone else has done, only better. This demonstrates that originality in entrepreneurship is actually an over-rated virtue. Imitation, on the other hand, is not just the sincerest form of flattery. It is one of the shrewdest ways to become a successful rebel entrepreneur.

An imitator in action

Image via CrunchBase

Take Lovefilm, the highly successful UK-based startup that has made renting DVD films and television box sets across Europe as easy as going to the post box or getting online. In January 2011, barely 12 years after it was founded, the company had over 1,500,000 members, each paying a monthly subscription of about £8, a catalogue of over 67,000 film and television program titles, and over 4 million rentals per month across five countries.

Amazon founder Jeff Bezos starts his High Order Bit presentation. (Photo credit: Wikipedia)

The premise of Lovefilm's business model is simple. Customers pay a monthly fee to receive a number of DVDs or games discs in the post, or the right to download a given quantity over the Internet to a TV or tablet device. They can play the games and watch the films as much as they like, and keep them as long as they like, but they will not get a new one until they return the ones they already have. Lovefilm is able to do this because in most western European countries there are two very reliable delivery mechanisms--one very modern (the Internet) and the other Victorian (the postal service).
Lovefilm's customers pay a subscription to the company, log onto the website and set up lists of favorite films or games, which are ranked as high, medium or low priority. Lovefilm then picks one or two of these, depending on the customer's price plan, and according to availability in the warehouse, and pops them in the mail. Both the old and the new technology work.
Since its creation, Lovefilm has developed its offering to allow customers to bypass the old-economy postal system entirely by streaming video over the Internet to get films 'on demand' on their home computer, games console, TV, tablet computer or smartphone.
Pretty neat, huh? Yes, except Lovefilm is completely unoriginal.

The original

Image via CrunchBase

Reed Hastings pioneered the idea of DVD rental by post in California back in 1997, allegedly after his shock at receiving a bill for $40 in late fees from Blockbuster. Hastings had to fine-tune his original idea to make it work. Initially the business model for his company, Netflix, was for customers to pay for each rental individually. In September 1999, he changed this and Netflix started offering monthly subscriptions. The pay-per-rental model was dropped completely a few months later.
It was not for another three years that Lovefilm began trading in Europe. There were advantages to this. By that time, people had been able to see that the idea worked, helping Lovefilm's founders to put their case when they needed backing from investors or to recruit key personnel.

Founder and CEO of Netflix, Reed Hastings, class of 1983 (Photo credit: Wikipedia)

Amazon bought Lovefilm in 2011, making multimillionaires of its investors. This brought the links with Netflix full circle, given that Lovefilm is now part of a U.S. company.
Amazon had seen the potential of the online DVD rental market at first hand with Netflix. Its founder, Jeff Bezos, has a reputation for constantly trying to stretch the Amazon brand into new areas. His approach has often been to try things himself before buying one of the best players in the market--another way of grabbing someone else's good idea. This is exactly what he did with the online DVD rental model. Amazon tried building its own video rental service, based on people downloading titles from its website. This was not as successful as Mr. Bezos would have liked, so he bought Lovefilm instead.
Imitator brands have clearly been a benefit for Amazon. In a way they have acted as the research and development function of Amazon, honing the service until it was ready for Amazon to acquire.

Unlock Your Inner Rain Man by Electrically Zapping Your Brain

Electrically stimulating the brain could make you smarter. Image: Allan Snyder

Imagine a creativity cap. A device that would free you, if only momentarily, from your mindsets, from your prejudices, from the mental blocks to creativity.

These words are emblazoned on the website Creativitycap.com, and they represent the vision of neuroscientist Allan Snyder. Snyder believes we all possess untapped powers of cognition, normally seen only in rare individuals called savants, and accessing them might take just a few jolts of electricity to the brain.

It sounds like a Michael Crichton plot, but Snyder, of the University of Sydney, Australia, says he wouldn’t be surprised to see a prototype of the creativity cap within a couple of years. His research suggests that brain stimulation improves people’s ability to solve difficult problems. But Snyder’s interpretation of his findings remains controversial, and the science of using brain stimulation to boost thinking is still in its early stages.

“I think it’s a bit of a minefield,” said psychologist Robyn Young of Flinders University in Australia, who has tried to replicate Snyder’s early experiments. “I’m not really sure whether the technology is developed that can turn it into a more accurate science.”

Snyder has long been fascinated by savants — people with a developmental brain disorder (often autism) or brain injury who display prowess in a particular area, such as mathematics, art or music, which far exceeds the norm. Kim Peek, who provided the inspiration for Dustin Hoffman’s character in the movie “Rain Man,” was a savant who could memorize entire books after a single reading, or instantly calculate what day of the week any calendar date fell on. But he had a severe mental disability that prevented him from performing simple actions such as buttoning his shirt.

The Codex of Alchemical Engineering [game]

Wanted to share "The Codex of Alchemical Engineering", which is a great Flash game!

Like Alchemy, but More Tangible!

The Codex of Alchemical Engineering is a puzzle game about programming “manipulators” to move, transmute, and bind alchemical “atoms” into complex compounds.
A few notes about the game:

• After completing a level, your progress is saved so long as your Flash “cookies” aren’t deleted. Your design, however, is not; if you want to keep your design, you must go to the Save screen and save the text shown there (I keep my solutions in a text file on my desktop). You can reload a saved design by pasting the design code into the Load window and pressing the load button.
• The music playing is Evan’s “Rever… Peut-etre…”, which you can find here on jamendo.com.

Requires: Flash

Increasing processor efficiency by 'shutting off the lights'

To promote energy-efficient multitasking, Harvard graduate student Wonyoung Kim has developed and demonstrated a new device with the potential to reduce the power usage of modern processing chips.

Image courtesy of Wonyoung Kim

The multicore voltage regulator responds almost instantaneously to changes in power demand from each core of the processor. As a result, the power supply matches the demand more closely, conserving energy.

There was a time when a laptop could weigh 10 pounds and still sell, a time when a cell phone was larger than a pocket, and a time when an iPod played only music.
Today’s consumers expect mobile devices that are both smaller and more powerful. All the bells and whistles, however, suck up energy — and a phone that lasts only four hours because it’s also a GPS device is only so useful.
To promote energy-efficient multitasking, Harvard graduate student Wonyoung Kim has developed and demonstrated a new device with the potential to reduce the power usage of modern processing chips.
The advance could allow the creation of “smarter” smartphones, slimmer laptops, and more energy-friendly data centers.
Kim’s on-chip, multicore voltage regulator (MCVR) addresses what amounts to a mismatch between power supply and demand.
“If you’re listening to music on your MP3 player, you don’t need to send power to the image and graphics processors at the same time,” Kim says. “If you’re just looking at photos, you don’t need to power the audio processor or the HD video processor.
“It’s like shutting off the lights when you leave the room.”

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