Navigation Links
Rice University lab develops technique to control light from nanoparticles
Date:9/29/2011

A nanoscale game of "now you see it, now you don't" may contribute to the creation of metamaterials with useful optical properties that can be actively controlled, according to scientists at Rice University.

A Rice laboratory led by chemist Stephan Link has discovered a way to use liquid crystals to control light scattered from gold nanorods. The researchers use voltage to sensitively manipulate the alignment of liquid crystal molecules that alternately block and reveal light from the particles; the gold nanorods collect and retransmit light in a specific direction.

The research was reported in the American Chemical Society journal Nano Letters.

It seems simple, but Link said the technique took two years to refine to the point where light from the nanoparticles could be completely controlled.

"The key to our approach is the in-plane rotation of liquid crystal molecules covering individual gold nanorods that act as optical antennas," said Link, an assistant professor of chemistry and electrical and computer engineering. "Learning how our devices work was exciting and has provided us with many ideas of how to manipulate light at the nanoscale."

Link said the device is actually a super half wave plate, a refined version of a standard device that alters the polarization of light.

With the new device, the team expects to be able to control light from any nanostructure that scatters, absorbs or emits light, even quantum dots or carbon nanotubes. "The light only has to be polarized for this to work," said Link, who studies the plasmonic properties of nanoparticles and recently authored a perspective on his group's recent research in plasmonics for the Journal of Physical Chemistry Letters. (View a video of Link and his team here.)

In polarized light, like sunlight reflecting off water, the light's waves are aligned in a particular plane. By changing the direction of their alignment, liquid crystals can tunably block or filter light.

The Rice team used gold nanorods as their polarized light source. The rods act as optical antennas; when illuminated, their surface plasmons re-emit light in a specific direction.

In their experiment, the team placed randomly deposited nanorods in an array of alternating electrodes on a glass slide; they added a liquid crystal bath and a cover slip. A polyimide coating on the top cover slip forced the liquid crystals to orient themselves parallel with the electrodes.

Liquid crystals in this homogenous phase blocked light from nanorods turned one way, while letting light from nanorods pointed another way pass through a polarizer to the detector.

What happened then was remarkable. When the team applied as little as four volts to the electrodes, liquid crystals floating in the vicinity of the nanorods aligned themselves with the electric field between the electrodes while crystals above the electrodes, still under the influence of the cover slip coating, stayed put.

The new configuration of the crystals -- called a twisted nematic phase -- acted like a shutter that switched the nanorods' signals like a traffic light.

"We don't think this effect depends on the gold nanorods," Link said. "We could have other nano objects that react with light in a polarized way, and then we could modulate their intensity. It becomes a tunable polarizer."

Critical to the experiment's success was the gap in the neighborhood of 14 microns -- between the top of the electrodes and the bottom of the cover slip. "The thickness of this gap determines the amount of rotation," Link said. "Because we created the twisted nematic in-plane and have a certain thickness, we always get 90-degree rotation. That's what makes it a super half wave plate."

Link sees great potential for the technique when used with an array of nanoparticles oriented in specific directions, in which each particle would be completely controllable, like a switch.


'/>"/>

Contact: David Ruth
druth@rice.edu
713-348-6327
Rice University
Source:Eurekalert

Related biology technology :

1. Parent Project Muscular Dystrophy Awards End Duchenne Grant to University of Pennsylvanias Dr. Tejvir S. Khurana
2. University of Western Ontario researchers investigate stress and breast cancer
3. SanBio Announces Site Opening of Phase 1/2a Clinical Trial of Novel Cell Therapy in Stable Stroke Patients at University of Pittsburgh Medical Center
4. HUYA Bioscience International Forms Alliance With Zhejiang Chinese Medical University Life Science College
5. Swedish University Hospital Improves Monitoring of Treatment Efficacy in Multiple Sclerosis With Synthetic MRI Innovation
6. University of Houston receives NSF grant for high school teachers program
7. New nanoscale parameter by Aalto University resolves dilemmas on silicon property
8. University of Muenster Bridges 1st Patient to Transplant with SynCardias Total Artificial Heart
9. Elsevier and the National University of Singapore Announce Winners of 24-Hour Hackathon
10. The Human Brain is Sensitive to Light, Breakthrough Findings From Valkee and the University of Oulu
11. CEM President and CEO Delivers Commencement Address at the University of Texas at Austin Chemistry and Biochemistry Department Graduation
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:2/24/2017)... ... February 24, 2017 , ... Chef Jodi Abel has returned ... Making stops in several cities, she gained a number of delicious recipes and new ... a town in South Africa’s Western Cape province. It is internationally renowned for ...
(Date:2/24/2017)... , Feb. 24, 2017 Symic Bio, a ... a new category of therapeutics, announced today the completion ... in peripheral artery disease. The trial will evaluate the ... therapeutic, in the reduction of restenosis following angioplasty. ... development milestone for SB-030," said Nathan Bachtell , ...
(Date:2/24/2017)... (PRWEB) , ... February 24, 2017 , ... FireflySci, Inc ... Founded in late 2014, FireflySci had the goal of bringing their powerful cuvette ... continues to shape the path that FireflySci is going on as they add yet ...
(Date:2/24/2017)... Feb. 24, 2017  OncoSec Medical Incorporated ("OncoSec") (NASDAQ: ... host a Key Opinion Leader event to highlight new ... and poster presentation at the upcoming 2017 ASCO-SITC Immuno-Oncology ... event will be held in-person and via live webcast ... 9:00 AM PST at the Lotte New York Palace ...
Breaking Biology Technology:
(Date:1/31/2017)... , Jan. 31, 2017  Spero Therapeutics, ... therapies for the treatment of bacterial infections, today ... of antibacterial candidates from Pro Bono Bio Ltd ... prevalence of multi-drug resistant forms of Gram-negative bacteria.  ... Anti Infectives Ltd, a PBB group company. ...
(Date:1/26/2017)... , Jan. 26, 2017  Crossmatch, a leading ... a new solution aimed at combatting fraud, waste and ... was introduced at the Action on Disaster Relief conference ... meeting point for UN agencies and foreign assistance organizations ... Fraud, waste and abuse are a largely unacknowledged problem ...
(Date:1/25/2017)... Jan. 25, 2017 The Elements of Enterprise ... lifecycle is comprised of a comprehensive set of ... of maintaining digital identities and providing a secured ... There are significant number of programs opted by ... time by optimizing processes and changing policies. However, ...
Breaking Biology News(10 mins):