 |
|
Researchers set new record for brightness of quantum dots
September 26, 2007CHAMPAIGN, Ill. -- By placing quantum dots on a specially designed photonic crystal, researchers at the University of Illinois have demonstrated enhanced fluorescence intensity by a factor of up to 108. Potential applications include high-brightness light-emitting diodes, optical switches and personalized, high-sensitivity biosensors.
"We are using photonic crystals in a new way," said Brian Cunningham, a professor of electrical and computer engineering and corresponding author of a paper published in the August issue of the journal Nature Nanotechnology. "We tune them to the specific wavelength of a laser used to stimulate the quantum dots, which couples the energy more efficiently and increases the brightness."
A quantum dot is a tiny piece of semiconductor material 2 to 10 nanometers in diameter (a nanometer is 1 billionth of a meter). When illuminated with invisible ultraviolet light, a quantum dot will fluoresce with visible light.
To enhance the fluorescence, Cunningham and colleagues at the U. of I. begin by creating plastic sheets of photonic crystal using a technique called replica molding. Then they fasten commercially available quantum dots to the surface of the plastic.
"We designed the photonic crystal to efficiently capture the light from an ultraviolet laser and to concentrate its intensity right within the surface where the quantum dots are located," said Cunningham, who also is affiliated with the university's Beckman Institute, the Micro and Nanotechnology Laboratory, and the Institute for Genomic Biology. "Enhanced absorption by the quantum dots is the first improvement we made."
Enhanced, directed emission from the quantum dots is the second improvement.
Quantum dots normally give off light in all directions. However, because the researchers' quantum dots are sitting on a photonic crystal, the energy can be channeled in a preferred direction - toward a detector, for example.
While the researchers report an enhancement of fluorescence intensity by a factor of up to 108 compared with quantum dots on an unpatterned surface, more recent (unpublished) work has exceeded a factor of 550.
"The enhanced brightness makes it feasible to use photonic crystals and quantum dots in biosensing applications from detecting DNA and other biomolecules, to detecting cancer cells, spores and viruses," Cunningham said. "More exotic applications, such as personalized medicine based on an individual's genetic profile, may also be possible."
University of Illinois at Urbana-Champaign
To enhance the fluorescence, Cunningham and colleagues at the U. of I. begin by creating plastic sheets of photonic crystal using a technique called replica molding. Then they fasten commercially available quantum dots to the surface of the plastic.
"We designed the photonic crystal to efficiently capture the light from an ultraviolet laser and to concentrate its intensity right within the surface where the quantum dots are located," said Cunningham, who also is affiliated with the university's Beckman Institute, the Micro and Nanotechnology Laboratory, and the Institute for Genomic Biology. "Enhanced absorption by the quantum dots is the first improvement we made."
Enhanced, directed emission from the quantum dots is the second improvement.
Quantum dots normally give off light in all directions. However, because the researchers' quantum dots are sitting on a photonic crystal, the energy can be channeled in a preferred direction - toward a detector, for example.
While the researchers report an enhancement of fluorescence intensity by a factor of up to 108 compared with quantum dots on an unpatterned surface, more recent (unpublished) work has exceeded a factor of 550.
"The enhanced brightness makes it feasible to use photonic crystals and quantum dots in biosensing applications from detecting DNA and other biomolecules, to detecting cancer cells, spores and viruses," Cunningham said. "More exotic applications, such as personalized medicine based on an individual's genetic profile, may also be possible."
University of Illinois at Urbana-Champaign
Quantum Dots Current Events and Quantum Dots News RSSFast quantum computer building block created
The fastest quantum computer bit that exploits the main advantage of the qubit over the conventional bit has been demonstrated by researchers at University of Michigan, U.S. Naval Research Laboratory and the University of California at San Diego.
Light touch: Controlling the behavior of quantum dots
Researchers from the National Institute of Standards and Technology (NIST) and the Joint Quantum Institute (JQI), a collaborative center of the University of Maryland and NIST, have reported a new way to fine-tune the light coming from quantum dots by manipulating them with pairs of lasers.
Nanoparticles + light = dead tumor cells
Medical physicists at the University of Virginia have created a novel way to kill tumor cells using nanoparticles and light.
New paper offers insights into 'blinking' phenomena
A new paper by a team of researchers led by University of Notre Dame physicist Bolizsár Jankó provides an overview of research into one of the few remaining unsolved problems of quantum mechanics.
Microwave synthesis connects with the (quantum) dots
Materials researchers at the National Institute of Standards and Technology (NIST) have developed a simplified, low-cost process for producing high-quality, water-soluble "quantum dots" for biological research.
Research measures movement of nanomaterials in simple model food chain
New research shows that while engineered nanomaterials can be transferred up the lowest levels of the food chain from single celled organisms to higher multicelled ones, the amount transferred was relatively low and there was no evidence of the nanomaterials concentrating in the higher level organisms.
Research shines spotlight on a key player in the dance of chromosomes
Cell division is essential to life, but the mechanism by which emerging daughter cells organize and divvy up their genetic endowments is little understood. In a new study, researchers at the University of Illinois and Columbia University report on how a key motor protein orchestrates chromosome movements at a critical stage of cell division.
All done with mirrors: NIST microscope tracks nanoparticles in 3-D
A clever new microscope design allows nanotechnology researchers at the National Institute of Standards and Technology (NIST) to track the motions of nanoparticles in solution as they dart around in three dimensions.
Stanford researchers hear the sound of quantum drums
Forty years ago, mathematician Mark Kac asked the theoretical question, "Can one hear the shape of a drum?"
JILA solves problem of quantum dot 'blinking'
Quantum dots-tiny, intense, tunable sources of colorful light-are illuminating new opportunities in biomedical research, cryptography and other fields. But these semiconductor nanocrystals also have a secret problem, a kind of nervous tic. They mysteriously tend to "blink" on and off like Christmas tree lights, which can reduce their usefulness.
More Quantum Dots Current Events and Quantum Dots News Articles
 | Wells, Wires and Dots: Theoretical and Computational Physics of Semiconductor Nanostructures by Paul Harrison Quantum Wells, Wires and Dots Second Edition: Theoretical and Computational Physics of Semiconductor Nanostructures provides all the essential information, both theoretical and computational, for complete beginners to develop an understanding of how the electronic, optical and transport properties of quantum wells, wires and dots are calculated. Readers are lead through a series of simple... |
 | The Quantum Dot: A Journey into the Future of Microelectronics by Richard Turton Since first developed in the early sixties, silicon chip technology has made vast leaps forward. From a rudimentary circuit with a mere handful of transistors, the chip has evolved into a technological miracle, packing millions of bits of information on a surface no larger than a human thumbnail. And most experts predict that in the near future, we will see chips with over a billion bits. At the... |
 | Electron Transport in Quantum Dots Electron Transport in Quantum Dots is a timely review covering topics such as the Kondo effect and spin-dependent transport in tunnel coupled dots, quantum chaos in open quantum dots and antidot arrays, and explorations of the novel technological applications of quantum dots and carbon nanotubes. It is unique in that it: - Brings together contributions from some of the most widely-recognized... |
 | Optics of Quantum Dots and Wires (Artech House Solid-State Technology Library) Quantum technology is the key to next-generation optoelectronics and laser semiconductors, and this new cutting-edge book is an in-depth examination of how quantum dots and wires are fabricated and applied to optics. You find a solid tutorial on the optical properties of nanoscale dots and wires that explains the current state of this technology and why it is so promising. The book presents a... |
 | Single Quantum Dots: Fundamentals, Applications and New Concepts (Topics in Applied Physics) This book reviews recent advances in the exciting and rapid growing field of semiconductor quantum dots by contributions from some of the most prominent researchers in the field. Special focus is given to the optical and electronic properties of single quantum dots due to their potential applications in devices operating with single electrons and/or single photons. This includes quantum dots in... |
 | Self-Assembled Quantum Dots (Lecture Notes in Nanoscale Science and Technology) In recent years, the field of self-assembled quantum dots has shown great promise for nanoscale applications in optoelectronics and quantum computing. Worldwide efforts in both theory and experimental investigations have driven the growth, characterization, and applications of quantum dots into an advanced multidisciplinary field. Written by leading experts in the field, Self-Assembled Quantum... |
 | Quantum Dot Lasers (Series on Semiconductor Science and Technology, 11) by Victor M. Ustinov, Alexey E. Zhukov, Anton Y. Egorov, Nikolai A. Maleev The book addresses issues associated with physics and technology of injection lasers based on self-organized quantum dots. Fundamental and technological aspects of quantum dot edge-emitting lasers and VCSELs, their current status and future prospects are summarized and reviewed. Basic principles of QD formation using self-organization phenomena are reviewed. Structural and optical properties of... |
 | Semiconductor Quantum Dots Semiconductor quantum dots represent one of the fields of solid state physics that have experienced the greatest progress in the last decade. Recent years have witnessed the discovery of many striking new aspects of the optical response and electronic transport phenomena. This book surveys this progress in the physics, optical spectroscopy and application-oriented research of semiconductor... |
 | Quantum Dots: Applications in Biology (Methods in Molecular Biology) Quantum Dots captures many diverse applications enabling utility in biological detection. Organized into five parts, the first two parts cover the use of QDs in imaging fixed and living cells (and tissues). Protocols are included for using QDs in routine (protein and structural cellular labeling), as well as enabling (single receptor trafficking, clinical pathology, correlative microscopy)... |
 | Quantum Dots by T. Chakraborty This book deals with the electronic and optical properties of two low-dimensional systems: quantum dots and quantum antidots and is divided into two parts. Part one is a self-contained monograph which describes in detail the theoretical and experimental background for exploration of electronic states of the quantum-confined systems. Starting from the single-electron picture of the system, the... |
| © 2008 BrightSurf.com |