|
Professor David Erickson | Using a beam of light shunted through a tiny silicon channel, researchers from the Erickson lab in MAE in collaboration with the Lipson Lab in ECE have created a nanoscale trap that can stop free floating DNA molecules and nanoparticles in their tracks. By holding the biological material steady while the fluid around it flows freely, the trap may allow researchers to boost the accuracy of biological sensors and create a range of new “lab on a chip” diagnostic tools.
The team research team reports its findings in the January 1, 2009 issue of the journal Nature. Experiments and simulations for the work were conducted by Ph.D. student’s Allen Yang, Sean Moore and M.Eng. student Matthew Klug in the Erickson lab and Ph.D. student Bradley Schmidt in the Lipson lab.
Light has been used to manipulate cells and even nanoscale objects before, but the new technique allows researchers to manipulate the particles more precisely and over longer distances.
“At the nanoscale, we can think of light like a series of massless particles called photons," says Professor Erickson. "We've demonstrated a way to condense these photons down to a very small area and stream them along a special type of waveguide, a device that acts like a nanoscale optical fiber. When pieces of matter, like DNA or nanoparticles, float near these streaming photons, they are sucked in and pushed along with the flow. The effect is sort of like moving a truck by throwing baseballs at it. The trick is that we found a way to have a large number of highly efficient "collisions" between the photons and the nanoparticles, getting them to stay in our device and keep them moving along it." |
To perform the experiments the team crafted a wave guide to shunt light into a narrow beam, laying a trap for the DNA and other small pieces of material. Each of the tiny channels within the waveguide is only 60-120 nanometers (billionths of a meter) wide, thinner than the 1,500 nanometer wavelength of the infrared laser light channeling through them. The channels keep the light waves focused and enhance their ability to interact with the DNA particles, preventing them from flowing by.
In future iterations of the system, the light will both capture the particles and transport them, so the DNA would arrive at the trap and then be directed to another location, such as a sensor or a staging ground for the assembly of a structure.
Further information on the work is available from the Erickson lab website http://nano.mae.cornell.edu
Support for the research was provided by the National Science Foundation
Source: The National Science Foundation
Two parallel silicon bars, each acting as a channel for a light beam, form a slot waveguide. Because the channels are smaller than the wavelength of the light an "evanescent field" extends outside each one, and energy is concentrated where the fields overlap. | |
