'Nanocavity' Sensor Detects Virus-Sized Particles

Dec 20, 2007 By Laura Mgrdichian feature
'Nanocavity' Sensor Detects Virus-Sized Particles
The nanocavity sensor. Each cavity is only 240 nanometers (billionths of a meter) in diameter. Photo courtesy Philippe Fauchet.

Scientists have created a nanoscale device that is capable of detecting one quadrillionth of a gram of biological matter, or about the size of certain viruses. In the future, the sensor may be able to detect influenza, severe acute respiratory syndrome (SARS), bird flu, and other viruses.

The sensor was created by researchers from the University of Rochester in Rochester, New York, and is described in a recent edition of Optics Letters.

The sensor is a hexagonal array of tiny cavities, each 240 nanometers in diameter, carved into a very thin slab of silicon using a beam of electrons. It has a total sensing area of about 40 micrometers square, making it one of the smallest sensors of its type.

When a laser beam is directed into the crystal, it interacts with the crystal such that only a particular part of the light's spectrum is transmitted. But when a particle is trapped in one of the nanocavities, the transmitted spectrum changes slightly. A detector measures the altered spectrum.

“When a virus within a certain size range is caught in one of the nanocavities, the sensor transmits a light spectrum that is slightly different than the spectrum it transmits when no particles are present,” said University of Rochester engineer Philippe Fauchet, the project's corresponding researcher, to PhysOrg.com. “We can then compare the two spectra to determine whether the target particle was captured, which forms the basis for a very simple yet powerful biosensor that could be used by untrained personnel, such as front-line health care providers.”

Fauchet and co-researcher Mindy Lee watched the sensor successfully detect single latex “test” spheres with sizes comparable to a variety of viruses. These include influenza A (approximately 100 nanometers in diameter) and hepatitis (50 nanometers in diameter). With a few modifications, Fauchet and Lee say that the device will be able to move from latex spheres to actual viruses.

The sensor is classified as a “two-dimensional photonic crystal,” a type of nanostructure that causes photons to behave in a similar way as a semiconductor causes electrons to behave. That is, only photons having frequencies within a certain range can be transmitted through the crystal, much like how electrons can only move through a semiconductor if they have certain energies.

“One dimensional” silicon-based photonic crystals, which are very, very thin, have been used to detect DNA, proteins, and bacteria. However, they only work properly if the laser beam is well collimated (the rays are nearly parallel). In turn, this requires that the sensing area is relatively large, which is not the desired trend. Fauchet and Lee's device removes these restrictions.

Citation: Optics Letters / Vol. 32, No. 22 / November 15, 2007

Copyright 2007 PhysOrg.com.
All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of PhysOrg.com.

Explore further: A nanosized hydrogen generator

add to favorites email to friend print save as pdf

Related Stories

A small step toward discovering habitable Earths

Mar 05, 2014

University of Arizona researchers snapped images of a planet outside our solar system with an Earth-based telescope using essentially the same type of imaging sensor found in digital cameras instead of an ...

Fine-tuning a rainbow of colors at the nanoscale

Feb 11, 2014

(Phys.org) —TVs, image sensors, iPads, digital cameras and other modern devices use filters to display the breadth of colors available in the visible portion of the electromagnetic spectrum.

Probing the inner secrets of nanowires

Dec 13, 2013

(Phys.org) —Semiconductor nanowires (NWs) are vanishingly small: NWs from a recent batch made by scientists in PML's Quantum Electronics and Photonics Division measure about 200 nanometers in diameter (less ...

High-tech measurements for high-frequency antennas

Nov 18, 2013

A team of researchers at PML's Antenna Metrology Lab in Boulder, CO has devised a first-of-its-kind system – combining a precision 3-meter industrial robot arm with a metrology-grade laser tracker and other ...

Recommended for you

A nanosized hydrogen generator

Sep 20, 2014

(Phys.org) —Researchers at the US Department of Energy's (DOE) Argonne National Laboratory have created a small scale "hydrogen generator" that uses light and a two-dimensional graphene platform to boost ...

For electronics beyond silicon, a new contender emerges

Sep 16, 2014

Silicon has few serious competitors as the material of choice in the electronics industry. Yet transistors, the switchable valves that control the flow of electrons in a circuit, cannot simply keep shrinking ...

Making quantum dots glow brighter

Sep 16, 2014

Researchers from the University of Alabama in Huntsville and the University of Oklahoma have found a new way to control the properties of quantum dots, those tiny chunks of semiconductor material that glow ...

The future face of molecular electronics

Sep 16, 2014

The emerging field of molecular electronics could take our definition of portable to the next level, enabling the construction of tiny circuits from molecular components. In these highly efficient devices, ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

1 / 5 (1) Dec 30, 2007
That's the first step to those SF bio readers for when we have to visit other star systems.

Also... next time we go to the moon, we should have those things with us. Much safer...