Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Solid-State Lighting Sources Getting More Energy Efficient and Smart

31.05.2005


Rensselaer Researchers Detail Potential for Smart Lighting in Science



“Smart” solid-state light sources now being developed not only have the potential to provide significant energy savings, but also offer new opportunities for applications that go well beyond the lighting provided by conventional incandescent and fluorescent sources, according to E. Fred Schubert and Jong Kyu Kim of Rensselaer Polytechnic Institute.

In an article published May 27, 2005 in the journal Science, the authors describe research currently under way to transform lighting into “smart” lighting, with benefits expected in such diverse fields as medicine, transportation, communications, imaging, and agriculture. The ability to control basic light properties — including spectral power distribution, polarization, and color temperature — will allow “smart” light sources to adjust to specific environments and requirements and to undertake entirely new functions that are not possible with incandescent or fluorescent lighting.


For example, “smart” solid-state light sources have the potential to adjust human circadian rhythms to match changing work schedules, to allow an automobile to imperceptibly communicate with the car behind it, or to economically grow out-of-season strawberries in northern climates, according to Professors Schubert and Kim.

Solid-state lighting sources such as light-emitting diodes (LEDs) already offer energy savings and environmental benefits compared to traditional incandescent or fluorescent lamps, say Schubert, the Wellfleet Senior Constellation Professor of the Future Chips Constellation at Rensselaer, and Kim, a post-doctoral fellow. Fundamental principles of physics place far greater limits on the efficiency of incandescent and fluorescent lights than on solid-state lights. In theory, solid-state devices with perfect materials and designs would require only 3 watts to generate the light obtained from a 60-watt incandescent bulb.

Solid-state sources potentially could cut in half the 22 percent of electricity now consumed by lighting. Traffic lights using LEDs, for example, use only one-tenth the power of signals using incandescent lamps. Further development of solid-state sources to replace traditional lighting will reduce energy consumption and dependency on oil and decrease emissions of greenhouse gases, acid-rain-causing sulphur dioxide, and mercury.

However, it is the possibility of controlling such basic properties of solid-state lighting as spectral content, emission pattern, polarization, color temperature, and intensity that gives these light sources the ability to provide entirely new functions. For example:

Recent research shows that ganglion cells in the human eye, which are believed to be involved in the human circadian or wake-sleep rhythm, are most receptive to the light in the blue spectral range that is experienced midday under clear skies. According to a basic physics definition, this light has a high color temperature, while evening light has a far lower color temperature. Lighting that offers the ability to adjust color temperature could benefit human health, mood, and productivity.

The ability to rapidly modulate LED-based light sources gives these lights the potential to sense and broadcast information by blinking far too rapidly for the human eye to perceive. Auto brake lights, for example, could communicate an emergency braking maneuver to a following car.

The ability to control the spectral composition, polarization, and color temperature of light used in microscopy could greatly improve the clarity of images, enabling real-time identification, counting, and sorting of biological cells for research and medical applications. Controlling the spectral composition of grow lights would offer an energy-efficient method to grow fruits and vegetables out of season or in climates where they don’t usually flourish. To achieve these benefits, according to Schubert and Kim, improvements are needed in materials, device design and fabrication, and packaging of solid-state components into lamps and luminaires. Researchers must learn, for example, how to grow ultraviolet, green, yellow-green, and yellow emitters with improved internal quantum efficiencies.

To efficiently extract light from the LED chip and package, new methods are needed such as the omni-directional reflectors recently developed by a team led by Schubert. Several strategies are being pursued to increase the power per package, including scaling up the chip area, scaling up the current density, and increasing the maximum allowable operating temperature.

Scaling is particularly interesting, as it is reminiscent of the successful scaling in silicon technology that for decades has shrunk computers while increasing their power, say Schubert and Kim. The scaling up of LED chip size and current density will substantially reduce costs, bringing LEDs into offices, homes, and, perhaps, even dining room chandeliers, the authors say. In addition, low-cost availability of solid-state lighting devices will contribute to the development of a wide variety of totally new smart lighting functions.

See also Rensselaer’s on-line research magazine summer ’04 feature on "smart" lighting at Rensselaer: www.rpi.edu/research/magazine/summer04/lrc.html

About Rensselaer
Rensselaer Polytechnic Institute, founded in 1824, is the nation’s oldest technological university. The university offers bachelor’s, master’s, and doctoral degrees in engineering, the sciences, information technology, architecture, management, and the humanities and social sciences. Institute programs serve undergraduates, graduate students, and working professionals around the world. Rensselaer faculty are known for pre-eminence in research conducted in a wide range of fields, with particular emphasis in biotechnology, nanotechnology, information technology, and the media arts and technology. The Institute is well known for its success in the transfer of technology from the laboratory to the marketplace so that new discoveries and inventions benefit human life, protect the environment, and strengthen economic development.

Theresa Bourgeois | EurekAlert!
Further information:
http://www.rpi.edu

More articles from Power and Electrical Engineering:

nachricht Harvesting the Sun for Power and Produce
24.11.2017 | Fraunhofer-Institut für Solare Energiesysteme ISE

nachricht Batteries with better performance and improved safety
23.11.2017 | Empa - Eidgenössische Materialprüfungs- und Forschungsanstalt

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New proton record: Researchers measure magnetic moment with greatest possible precision

High-precision measurement of the g-factor eleven times more precise than before / Results indicate a strong similarity between protons and antiprotons

The magnetic moment of an individual proton is inconceivably small, but can still be quantified. The basis for undertaking this measurement was laid over ten...

Im Focus: Frictional Heat Powers Hydrothermal Activity on Enceladus

Computer simulation shows how the icy moon heats water in a porous rock core

Heat from the friction of rocks caused by tidal forces could be the “engine” for the hydrothermal activity on Saturn's moon Enceladus. This presupposes that...

Im Focus: Nanoparticles help with malaria diagnosis – new rapid test in development

The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.

Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

IceCube experiment finds Earth can block high-energy particles from nuclear reactions

24.11.2017 | Physics and Astronomy

A 'half-hearted' solution to one-sided heart failure

24.11.2017 | Health and Medicine

Heidelberg Researchers Study Unique Underwater Stalactites

24.11.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>