Magnetic sensors - a new slant on an old technology

Paul and his team have developed new techniques to micro-fabricate flux-gate magnetic sensors, producing tiny versions of these sensors which are:

-- extremely sensitive
-- contained in a miniature package
-- able to work over a wide frequency range

These properties allow the sensors to be used in a range of new applications including the measurement of electrical currents in circuits and the evaluation of the magnetic properties of materials - both of which can be achieved in a non-destructive manner.

One example of this is a magnetic microscope, in which the magnetic sensor is scanned over the surface of an item and the measured magnetic field is displayed as an image on a computer screen. Currently, magnetic microscopes are commercially available which use highly cooled superconducting sensors, but the sensors being developed here in the Department operate at room temperature - resulting in a much lower system cost.

Possible uses for such an instrument include surface defect detection in components and the development of ticketing, security cards, anti-counterfeiting devices and security features on bank notes, as all of these contain magnetic recording material. These pictures show images of current flow around a PCB track and part of George Washington's face - as printed in magnetic ink on a US dollar bill, scanned with a system built in the Department.

Paul and his team are currently developing this technology with a local company for use in a new product - a novel type of current probe for use by electronics engineers. The project is now in the production engineering phase. Other areas of interest would be welcomed.

Source: University of Cambridge