Featured Research

from universities, journals, and other organizations

Silicon Nanoparticles Now Come In Family Of Sizes And Fluorescent Colors

Date:
January 24, 2002
Source:
University Of Illinois At Urbana-Champaign
Summary:
A process for creating silicon nanoparticles, developed at the University of Illinois, has now been shown to produce a family of discrete particle sizes useful for microelectronics, optoelectronics and biomedical applications.

CHAMPAIGN, Ill. — A process for creating silicon nanoparticles, developed at the University of Illinois, has now been shown to produce a family of discrete particle sizes useful for microelectronics, optoelectronics and biomedical applications.

As reported in the Jan. 21 issue of Applied Physics Letters, researchers demonstrated that the electrochemically etched particles come in particular sizes and fluoresce in distinct colors. The smallest four sizes are blue, green, yellow and red luminescent particles.

“The availability of specific particle size and emission in the red, green and blue range makes the particles useful for electronic displays and flash memories,” said Munir Nayfeh, a UI professor of physics and corresponding author of the APL paper. “The benign nature of silicon also makes the particles useful as ultra-bright fluorescent markers for tagging biologically sensitive materials.”

Current medical and biological fluorescent imaging is limited by the use of dye markers, which are not photostable, Nayfeh said. The dyes can break down under photoexcitation, room light or higher temperatures.

Not only are the new silicon particles photostable, they are also bright. The light from a single nanoparticle can be readily detected.

To convert bulk silicon into nanoparticles, Nayfeh and his colleagues use an electrochemical treatment that involves gradually immersing a silicon wafer into an etchant bath of hydrofluoric acid and hydrogen peroxide while applying an electrical current. The process erodes the surface layer of the material, leaving behind a delicate network of weakly interconnected nanostructures. The wafer is then removed from the etchant and immersed briefly in an ultrasound bath.

Under the ultrasound treatment, the fragile nanostructure network crumbles into individual particles, which may be easily separated into the different size groups.

“The availability of different colored markers is very important for biomedical applications,” said Nayfeh, who also is a researcher at the UI’s Beckman Institute for Advanced Science and Technology. “By placing particles of different colors in strategic locations, you could study such phenomena as growth factors in cancer cells or how proteins fold.”

The silicon particles fluoresce when struck with ultraviolet light. They also can fluoresce when struck with two photons of infrared light – a technique that can non-invasively penetrate human tissue. In a separate paper, published in the Jan. 7 issue of Applied Physics Letters, the researchers also demonstrated laser oscillation in small aggregates of the silicon nanoparticles.

“At 6 microns in diameter, these clusters of particles are one of the smallest lasers in the world,” said Sahraoui Chaieb, a UI professor of theoretical and applied mechanics and a co-author of both papers. “This microlasing is an important step towards the realization of a laser on a chip, which could ultimately replace wires with optical interconnects.”

The emission was dominated by a deep-red color, said Chaieb, who also is a researcher at the Beckman Institute. The clusters are currently stimulated by green light from a mercury lamp. One of the researchers’ goals is to excite them instead with electricity.

The research team included Nicholas Barry and Paul Braun at the UI and Lubos Mitas at North Carolina State University. Funding was provided by the National Science Foundation and the Illinois Department of Commerce and Community Affairs.


Story Source:

The above story is based on materials provided by University Of Illinois At Urbana-Champaign. Note: Materials may be edited for content and length.


Cite This Page:

University Of Illinois At Urbana-Champaign. "Silicon Nanoparticles Now Come In Family Of Sizes And Fluorescent Colors." ScienceDaily. ScienceDaily, 24 January 2002. <www.sciencedaily.com/releases/2002/01/020124174055.htm>.
University Of Illinois At Urbana-Champaign. (2002, January 24). Silicon Nanoparticles Now Come In Family Of Sizes And Fluorescent Colors. ScienceDaily. Retrieved July 30, 2014 from www.sciencedaily.com/releases/2002/01/020124174055.htm
University Of Illinois At Urbana-Champaign. "Silicon Nanoparticles Now Come In Family Of Sizes And Fluorescent Colors." ScienceDaily. www.sciencedaily.com/releases/2002/01/020124174055.htm (accessed July 30, 2014).

Share This




More Matter & Energy News

Wednesday, July 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Climate Change Could Cost Billions, According To White House

Climate Change Could Cost Billions, According To White House

Newsy (July 29, 2014) — A report from the White House warns not curbing greenhouse gas emissions could cost the U.S. billions. Video provided by Newsy
Powered by NewsLook.com
Stranded Whale Watching Boat Returns to Boston

Stranded Whale Watching Boat Returns to Boston

Reuters - US Online Video (July 29, 2014) — Passengers stuck overnight on a whale watching boat return safely to Boston. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Baluchistan Mining Eyes an Uncertain Future

Baluchistan Mining Eyes an Uncertain Future

AFP (July 29, 2014) — Coal mining is one of the major industries in Baluchistan but a lack of infrastructure and frequent accidents mean that the area has yet to hit its potential. Duration: 01:58 Video provided by AFP
Powered by NewsLook.com
Easier Nuclear Construction Promises Fall Short

Easier Nuclear Construction Promises Fall Short

AP (July 29, 2014) — The U.S. nuclear industry started building its first new plants using prefabricated Lego-like blocks meant to save time and prevent the cost overruns that crippled the sector decades ago. So far, it's not working. (July 29) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins