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February 13, 2012 Previous day Next day

"When you have a very tight lattice match, light generation happens far more efficiently... It really leads to LED 2.0 and a whole new disruptive technology curve." - Soraa CEO Eric Kim

 


 

● The Centre for Quantum Devices at Northwestern University, Evanston-Illinois, created the first UV HVPE-GaN (galium nitride) substrate LEDs in 2002 while experimenting with different materials. Increased efficiency and heat-dissipation were noted.

 

● Panasonic launched the industry's first white LED using a GaN substrate in 2007. The extremely expensive lamps were sparsely used. 

 

● In December 2010, Ostendo Technologies and Technologies and Devices International grew a LED structure onto a GaN substrate. This ended up in a 2.5x emission intensity increase. In other words, a energy efficiency increase compared to similar LEDs with the same luminosity. Their tech is used now in LED TVs, consoles and Blu-Ray players, automotive lighting, and solar cells.

 

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MR16 GaN on GaN LED (via Soraa)

 

● Now in 2012, "startup" company Soraa Inc has just announced their mass-produced MR16 bulb, a 12.5-watt GaN based luminary able to replace a 50-watt halogen fixtures in store and museum lighting applications. Soraa's LED also places the GaN light emitting semiconductor material onto a GaN substrate. Soraa labeled and trademarked the tech as "GaN on GaN™" LEDs. Matching the materials between the layers create uniformity within the entire LED system. In other words, with less imperfections the Soraa LED can handle more current, and produce more light at any given power level. Traditionally, LEDs are manufactured with silicon carbide or sapphire substrates. The lattice mismatch between the active material, GaN LED, and substrate result in a loss of power and efficiency.

 

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(via Soraa)

 

The GaN on GaN™ comes with one glaring disadvantage, cost. No price on the various lamp options, but Soraa CEO Eric Kim said, " If they could buy our bulb for a price point less than $25, their payback period is less than a year. At that price point, it's a no-brainer."

However, Paul Scheidt, marketing manager at competitor CREE, stated that making a GaN substrate LED would result in a cost "on the order of 50-100 times more expensive than an equivalent sapphire wafer. So, while the wafer cost doesn't matter too much in the world of GaN-on-sapphire LEDs, it definitely would be a major expense for GaN-on-GaN."

 

No true price has been announced. However, the first run of MR16 lamps will be available in the first quarter of 2012.

 

Soraa was founded in 2008 by a very able group; Dr. Shuji Nakamura, inventor of the blue laser and White LED,  Dr. Steven DenBaars, founder of Nitres, and Dr. James Speck of U.C. Santa Barbara's College of Engineering. Together, they were able to raise over $100 million USD in investment capital before solid prototypes were produced.

 

Although, what they are producing is not exactly new, they are one of the few who produce the tech on such a massive scale. Bringing the efficiencies to the large scale lighting space is the beginning of full LED adoption.

 

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See more lighting innovations in element14's Lighting Group.

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STCF04 (via STMicroelectronics)

 

Taking decent indoor pictures with a smartphone is almost impossible in low light conditions. Think about it; most of the time you have to take the same picture at least twice. The first one was blurry, and the second pic turns out dark because the flash on your phone (if it even has one) isn’t bright enough in low-light conditions. However, there is hope on the horizon with the help of STMicroelectronics new chip dubbed ‘STCF04’. The chip is actually a combination camera flash with a torch controller that raises the LED/flash module up to an astounding 40 watts of illumination ( 320mA current). This is in comparison to today’s standard of just 4 watts that ST states, “produces the same amount of light as a security flood lamp”.

 

The STCF04 uses a high-current MOSFET switch over a lower rated switch (currently housed in today’s generation of smartphones) along with a supercapacitor and high-power white LED’s that ST says can also be used as emergency flash lighting. With the help of the torch controller, users will be able to select 12 levels of brightness along with 8 levels for the flash controller to fine tune the users lighting needs. The chip is already being sampled by companies such as Murata which produce high-quality supercapacitors and OSRAM, makers of LED’s and solid-state lighting. Full production of the SCT04 will begin this quarter of 2012 and will sell for $2.00(US) for companies that buy a 1000 or more. With the STCF04 in the TFBGA package ( 3 x 3 mm) means that we can expect to see the STC04 in the next generation of smartphones. We will no longer have to explain the darkness of our pictures as ‘mood lighting.'

 

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Solar energy collection might just be the best alternative energy solution. It collects energy from outside the earth's ecosystem, instead of stealing the kinetic energy from the planet itself. If we are going to do so, collecting more of that energy is paramount. Up until now, commercial solar energy collection peak at around 15% light to energy transfer efficiency. Those standard returns have been shattered by a couple of companies out of the USA.

 

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Alta Devices solar panel (via University of California at Berkeley)

 

Founded in 2007, California based Alta Devices has collected well over 72 million USD in investment funding. At the Photovoltaic Specialists conference (PVSC37) Alta Devices demonstrated single-junction solar cells, made of gallium arsenide (GaAs),with a conversion efficiency of 27.6%, gaining them the world record for conversion under 1 Sun illumination. Maximum to date form Alta was 28.2%

 

Alta Devices co-founder and University of California at Berkeley Professor Eli Yablonovitch explained the tech behind the world record at PVSC37, "Up until now it was understood that to increase the current from our best solar materials, we had to find ways to get the material to absorb more light. But, the voltage is a different story. It was not recognized that to maximize the voltage, we needed the material to generate more photons inside the solar cell. Counter-intuitively, efficient light emission is the key for these high efficiencies.”

 

The photovoltaic (PV) boost from Alta Devices was later evaluated by the National Renewable Energy Laboratory (NREL) to have a consistent 23.5% conversion rate. To go along with the boost is an Alta invented manufacturing process where one micron thin GsAS layer, making for an extremely flexible solar cell. This process brings down the cost of the solar panel substantially. With price and efficiency into consideration, the Alta Devices cell is a close competitor to fossil fuels, even without subsidies.

 

The theoretical maximum efficiency for single junction cells is 33.5%, also known as the "Schocley-Queisser Limit." Alta strives to get even closer in the coming years.

 

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(Left) Semprius solar panel (via NREL) (Right) Die placeing solar dots on a substrate (via Semprius)

 

On the other side of the country, North Carolina based Semprius gains a 33.9% PV module efficiency (850w/m²). Semprius employs high-concentration PV (HCPV) Triple-junction GaAS cells. Even with the ability to print solar cells as small as a sentence period, Semprius is burdened with the high-cost of triple-junction cells. Never the less, it is the first time that over 1/3 of the sun's energy has been converted. The NREL recorded that with the concentration of 1,000 suns, the triple-junction was able to convert 41% of the energy.

 

Semprius CPV applications engineer Kanchan Ghosal  explained, "We're using a completely different approach to what has been practiced. This approach uses micro-cells and transfer printing to significantly reduce the use of materials in highly concentrated PV modules. And it provides a highly parallel method to manufacture the module, based on established microelectronics processes and equipment."

 

After inventing a way to lower solar-cell printing at Semprius, Seimens bought a 16% stake in the company. Coupled with over $38 million in other investments, Semprius make make a solar splash yet.

 

Either way one goes, there is a sizable return on investment cost with solar energy. Up to 5 years to pay off the cost of equipment is standard.  The efficiency boosts lower that time, initial cost still remains the number one hurdle to a wider adoption of solar.

 

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InductionPoweredMedicalDevice.jpgA wireless medical pressure transducer that Dr. Joshua Medow first prototyped in his home lab a few years ago is now being tested in sheep and could be tested in human patients within two years.

 

The device is intended for patients with hydrocephalus who have a shunt implanted to reduce  cerebrospinal fluid pressure.  When these patients have symptoms as simple as a headache, there is no easy test to determine if a failure of the shunt is responsible. 

 

Dr. Medow had an idea of implanting a pressure sensor in the brain and transmitting the data to a receiver outside the body.  He was knowledgeable about electronics, so he built a proof of concept using through-mount parts on a breadboard. 

 

The receiver provided power to the transmitter inductively by applying 60Hz AC to a coil.  The transmitter used a bridge rectifier and a linear to generate 15V DC.  He used this voltage to excite a strain gauge and to power an op-amp circuit and a voltage-to-frequency converter.  The output of the frequency converter was a function of the strain gauge deflection and was in the 800Hz range.  He did all of this with very old-school parts such as LM7815CTLM7815CT, LM324, LM331.  These are all parts I used frequently in the 90s when I started doing electronics, and they were already twenty years old at that time. 

Intercranial Pressure Sensor Block Diagram.jpg

 

This simple proof of concept led to prototypes that integrate all the circuitry in one piece of custom silicon and use MEMS to measure pressure.  The new pressure monitor transmits at at a higher frequency and uses the same antenna to transmit its data and receive power. 

 

It would have been easy for Medow to dismiss the project when he conceived it because he didn’t have the resources to create custom silicon.  Instead he built a prototype.  That led to a collaboration with engineers at the University of Wisconsin to produce a more advanced prototype.  Last fall, three years after the early prototype he was featured on the front page of the Wisconsin State Journal.  Now the technology is being tested in animals and is a few years away from human trials. 

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