Navigation Links
By 'putting a ring on it,' microparticles can be captured

Cambridge, Mass., July 20, 2010 To trap and hold tiny microparticles, engineers at Harvard have "put a ring on it," using a silicon-based circular resonator to confine particles stably for up to several minutes.

The advance, published in the June 14 issue of Nano Letters, could one day lead to the ability to direct, deliver, and store nanoparticles and biomolecules on all-optical chips.

"We demonstrated the power of what we call resonant cavity trapping, where a particle is guided along a small waveguide and then pulled onto a micro-ring resonator," explains Kenneth Crozier, an Associate Professor of Electrical Engineering at the Harvard School of Engineering and Applied Sciences (SEAS) who directed the research. "Once on the ring, optical forces prevent it from escaping, and cause it to revolve around it."

The process looks similar to what you see in liquid motion toys, where tiny beads of colored drops run along plastic tracksbut on much smaller scale and with different physical mechanisms. The rings have radii of a mere 5 to 10 micrometers and are built using electron beam lithography and reactive ion etching.

Specifically, laser light is focused into a waveguide. Optical forces cause a particle to be drawn down toward the waveguide, and pushed along it. When the particle approaches a ring fabricated close to the waveguide, it is pulled from the waveguide to the ring by optical forces. The particle then circulates around the ring, propelled by optical forces at velocities of several hundred micrometers-per-second.

While using planar ring resonators to trap particles is not new, Crozier and his colleagues offered a new and more thorough analysis of the technique. In particular, they showed that using the silicon ring results in optical force enhancement (5 to 8 times versus the straight waveguide).

"Excitingly, particle-tracking measurements with a high speed camera reveal that the large transverse forces stably localize the particle so that the standard deviation in its trajectory, compared to a circle, is as small as 50 nm," says Crozier. "This represents a very tight localization over a comparatively large distance."

The ultimate aim is to develop and demonstrate fully all-optical on chip manipulation that offers a way to guide, store, and deliver both biological and artificial particles.


Contact: Michael Patrick Rutter
Harvard University

Related biology news :

1. Putting a green cap on garbage dumps
2. Putting limits on vitamin E
3. Americans want Uncle Sams help putting healthy foods on their dinner table
4. Thrill-seeking holidaymakers are putting dolphins at risk
5. Thrill-seeking holiday-makers are putting dolphins at risk
6. Putting bacterial antibiotic resistance into reverse
7. Drug-embedded microparticles bolster heart function in animal studies
8. Scientists guide immune cells with light and microparticles
9. First known instance of a cricket as an orchid pollinator captured on film by Kew scientist
10. Caught on tape: Muscle stem cells captured on video by MU researcher
Post Your Comments:
Related Image:
By 'putting a ring on it,' microparticles can be captured
(Date:11/9/2015)... , Nov. 9, 2015  Synaptics Inc. (NASDAQ: ... today announced broader entry into the automotive market with ... match the pace of consumer electronics human interface innovation. ... are ideal for the automotive industry and will be ... Europe , Japan ...
(Date:11/2/2015)... , Nov. 2, 2015  SRI International has been ... provide preclinical development services to the National Cancer Institute ... will provide scientific expertise, modern testing and support facilities, ... preclinical pharmacology and toxicology studies to evaluate potential cancer ... The PREVENT Cancer Drug Development Program is an ...
(Date:10/29/2015)... Calif. , Oct. 29, 2015  The J. ... new report titled, "DNA Synthesis and Biosecurity: Lessons Learned ... the Department of Health and Human Services guidance for ... in 2010. --> ... it also has the potential to pose unique biosecurity ...
Breaking Biology News(10 mins):
(Date:11/24/2015)... ... November 24, 2015 , ... The Academy of Model ... Group (SIG), MultiGP, also known as Multirotor Grand Prix, to represent the First–Person View ... years. Many AMA members have embraced this type of racing and several new model ...
(Date:11/24/2015)... Israel , Nov. 24, 2015  Tikcro Technologies Ltd. (OTCQB: TIKRF) ... on December 29, 2015 at 11:00 a.m. Israel ... Electra Tower, 98 Yigal Allon Street, 36 th Floor, ... of Eric Paneth and Izhak Tamir to the ... Rami Skaliter as external directors; , approval of an amendment to ...
(Date:11/24/2015)... , ... November 24, 2015 , ... ... the environment are paramount. Insertion points for in-line sensors can represent a weak ... the InTrac 781/784 series of retractable sensor housings , which are designed ...
(Date:11/24/2015)... Nov. 24, 2015 /CNW Telbec/ - ProMetic Life Sciences Inc. ... that Mr. Pierre Laurin , President and Chief Executive ... the upcoming Piper Jaffray 27 th Annual Healthcare Conference ... December 1-2, 2015. st , at 8.50am ... meetings throughout the day. The presentation will be available live ...
Breaking Biology Technology: