Magnetic sensor device with field generators and sensor elements
AssigneeKoninklijke Philips Electronics N.V.
InventorsJeroen Hans Nieuwenhuis, Hans Van Zon, Josephus Arnodlus Henricus Maria Kahlman
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Abstract
The invention relates to a magnetic sensor device (10) comprising (a) excitation wires (11, 13) for generating a magnetic excitation field (B) that magnetizes particles (2) in an investigation region (5), and (b) a magnetic sensor element, for example a GMR sensor (12), for detecting reaction fields (B′) generated by the magnetized particles (2). The excitation wires (11, 13) and the GMR element (12) are driven by current pulses such that the average power dissipation is kept constant while the signal-to-noise ratio is optimized. The sampling frequency of said pulses is preferably larger than the thermal time constant (τ) of the magnetic sensor device (10).
Claims9
A magnetic sensor device (10) for the detection of magnetic particles (2) in an investigation region (5), comprising
- a) a magnetic field generator (11, 13) that is driven by an excitation current (Iexc) for generating a magnetic excitation field (B) in the investigation region (5);
- b) a magnetic sensor element (12) that is driven by a sensor current (Isense) for detecting magnetic reaction fields (B′) generated by the magnetized particles (2);
- c) a power supply unit (15) for providing simultaneous pulses of sensor current (Isense) and excitation current (Iexc) that are repeated with a sampling time interval (Δ) which is longer than the pulse duration (δ), wherein the sensor current (Isense) and the excitation current (Iexc) are zero between subsequent pulses.
A method for the detection of magnetized particles (2) in an investigation region (5), comprising
- a) providing a magnetic field generator (11, 13) with an excitation current (Iexc) for generating a magnetic excitation field (B) in the investigation region (5);
- b) providing a magnetic sensor element (12) with a sensor current (Isense) for detecting magnetic reaction fields (B′) generated by the magnetized particles (2);
- wherein the excitation current (Iexc) and the sensor current (Isense) are provided as simultaneous pulses that are repeated with a sampling time interval (Δ) which is longer than the pulse duration (δ), wherein the sensor current (Isense) and the excitation current (Iexc) are zero between subsequent pulses.
Dependencies are inferred from the claim text.