Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Chip-scale magnetic sensor draws on mini clock design

30.12.2004


A low-power, magnetic sensor about the size of a grain of rice that can detect magnetic field changes as small as 50 picoteslas--a million times weaker than the Earth’s magnetic field--has been demonstrated by researchers at the National Institute of Standards and Technology (NIST). Described in the Dec. 27 issue of Applied Physics Letters,* the device can be powered with batteries and is about 100 times smaller than current atom-based sensors with similar sensitivities, which typically weigh several kilograms (about 6 pounds).


Photo of the NIST chip-scale magnetometer. The sensor is about as tall as a grain of rice. The widest block near the top of the device is an enclosed, transparent cell that holds a vapor of rubidium atoms. Photo by Peter Schwindt/NIST



The new magnetic sensor is based on the principles of a NIST chip-scale atomic clock, announced in August 2004. Expected applications for a commercialized version of the new sensor could include hand-held devices for sensing unexploded ordnance, precision navigation, geophysical mapping to locate minerals or oil, and medical instruments.

Like the NIST chip-scale clock, the new magnetic sensor can be fabricated and assembled on semiconductor wafers using existing techniques for making microelectronics and microelectromechanical systems (MEMS). This offers the potential for low-cost mass production of sensors about the size of a computer chip. When packaged with associated electronics, the researchers believe the mini magnetometer will measure about 1 cubic centimeter or about the size of a sugar cube.


Magnetic fields are produced by the motion of electrons either in the form of an electrical current or in certain metals such as iron, cobalt and nickel. The NIST miniature magnetometer is sensitive enough to detect a concealed rifle about 12 meters (40 feet) away or a six-inch-diameter steel pipeline up to 35 meters (120 feet) underground.

The sensor works by detecting minute changes in the energy levels of electrons in the presence of a magnetic field. A tiny sample of the element rubidium is heated within a sealed, transparent cell to form a rubidium vapor. Light from a semiconductor laser is transmitted through the atomic vapor. In the presence of a magnetic field, the amount of laser light that is absorbed by the atoms changes and this is detected by a photocell. Larger magnetic fields produce proportionally bigger changes in the atomic energy levels and change the absorption by the atom.

The key advantages of the new sensor, says Peter Schwindt, one of the NIST developers, are its accuracy and sensitivity given its small size. So called "fluxgate" magnetometers achieve equivalent or better sensitivity but are much less accurate and much larger. They also detect only the portion of a magnetic field pointing along the sensor, while the atomic magnetometers detect the total field strength, a desirable capability for many magnetic imaging and search applications. Superconducting quantum interference devices (SQUIDs) are more sensitive, but must be cryogenically cooled, making them substantially larger, power hungry and more expensive. "Magnetoresistive" devices like those used in heads that read computer hard drives are small and cheap, but are typically less sensitive and less accurate. A separate NIST research group has developed a new magnetoresistive magnetic sensor.

Gail Porter | EurekAlert!
Further information:
http://www.nist.gov

More articles from Physics and Astronomy:

nachricht UNH scientists help provide first-ever views of elusive energy explosion
16.11.2018 | University of New Hampshire

nachricht NASA keeps watch over space explosions
16.11.2018 | NASA/Goddard Space Flight Center

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: UNH scientists help provide first-ever views of elusive energy explosion

Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.

Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...

Im Focus: A Chip with Blood Vessels

Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.

Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...

Im Focus: A Leap Into Quantum Technology

Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.

In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...

Im Focus: Research icebreaker Polarstern begins the Antarctic season

What does it look like below the ice shelf of the calved massive iceberg A68?

On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.

Im Focus: Penn engineers develop ultrathin, ultralight 'nanocardboard'

When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure

Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

“3rd Conference on Laser Polishing – LaP 2018” Attracts International Experts and Users

09.11.2018 | Event News

On the brain’s ability to find the right direction

06.11.2018 | Event News

European Space Talks: Weltraumschrott – eine Gefahr für die Gesellschaft?

23.10.2018 | Event News

 
Latest News

Purdue cancer identity technology makes it easier to find a tumor's 'address'

16.11.2018 | Health and Medicine

Good preparation is half the digestion

16.11.2018 | Life Sciences

Microscope measures muscle weakness

16.11.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>