Miniaturized magnetometers.
Magnetometers measure the direction and/or intensity of magnetic fields. They are used in space to monitor space weather — conditions in geospace where charged particles carried on the solar wind from the sun collide with Earth’s magnetic fields, sometimes producing solar storms capable of endangering satellites, bringing down power grids on Earth, and producing the phenomena known as auroras.
Joshua Semeter (ENG’92,’97), an ENG assistant professor of electrical and computer engineering, and Makhlouf Redjdal, an electrical and computer engineering research associate, are developing a new magnetometer, small and light enough to fly easily in space and sensitive enough to compete with the much bulkier fluxgate magnetometers that are the current industry standard.
The new magnetometers are based on the giant magneto-impedance (GMI) effect. Discovered in 1994, the GMI effect is observed in very small magnetic wires, about five one-thousandths of an inch in diameter. When a high-frequency current is passed through them in the presence of even a very small magnetic field, these wires produce very large changes in resistance.
The project uses GMI wires to design the next generation of magnetometers for space research. On Earth, these wires are used in automotive and transportations systems, industrial measurement, scientific applications, and health care. GMI wires are also being explored in research to separate biological molecules by binding them to magnetic microspheres. Ultimately, the wires may be incorporated into intravenous sensors to monitor cardiac health.
Semeter’s and Redjdal’s GMI magnetometers will use three wires at right angles to one another, enabling them to measure the direction, as well as the intensity, of magnetic fields. They will be packaged, along with the necessary electronics, in a box measuring about a half-inch by a half-inch by about three inches, and weighing only about 3.5 ounces. The researchers expect the cost of the smaller and more sensitive units to be about a hundredth that of current magnetometers.
The researchers will be collaborating with space scientists at the CAS Center for Space Physics to test the new magnetometers on sounding rockets. The research to build the prototype has been funded by one of this year’s SPRInG grants from the Office of the Provost.
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