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 Hope to discover sure signs of life on Mars? New research says look for the element vanadium
22.09.2017 | University of Kansas

nachricht Calculating quietness
22.09.2017 | Forschungszentrum MATHEON ECMath

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: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Rainbow colors reveal cell history: Uncovering β-cell heterogeneity

22.09.2017 | Life Sciences

Penn first in world to treat patient with new radiation technology

22.09.2017 | Medical Engineering

Calculating quietness

22.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>