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 Stanford researchers develop a new type of soft, growing robot
21.07.2017 | Stanford University

nachricht Team develops fast, cheap method to make supercapacitor electrodes
18.07.2017 | University of Washington

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: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

Im Focus: On the way to a biological alternative

A bacterial enzyme enables reactions that open up alternatives to key industrial chemical processes

The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....

Im Focus: The 1 trillion tonne iceberg

Larsen C Ice Shelf rift finally breaks through

A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...

Im Focus: Laser-cooled ions contribute to better understanding of friction

Physics supports biology: Researchers from PTB have developed a model system to investigate friction phenomena with atomic precision

Friction: what you want from car brakes, otherwise rather a nuisance. In any case, it is useful to know as precisely as possible how friction phenomena arise –...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

 
Latest News

NASA looks to solar eclipse to help understand Earth's energy system

21.07.2017 | Earth Sciences

Stanford researchers develop a new type of soft, growing robot

21.07.2017 | Power and Electrical Engineering

Vortex photons from electrons in circular motion

21.07.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>