Patent ID: 8120353

Claim:
A method for detecting a damaged magnetoresistive sensor, comprising: measuring a resistance of a first sensor upon application thereto of a positive bias current; measuring the resistance of the first sensor upon application thereto of a negative bias current; determining a difference in the measured resistances at positive and negative currents of the first sensor; measuring a resistance of a second sensor upon application thereto of a positive bias current; measuring the resistance of the second sensor upon application thereto of a negative bias current; determining a difference in the measured resistances at positive and negative currents of the second sensor; outputting at least one of the differences, or a derivative of the at least one of the differences; diagnosing the first sensor as being damaged if a magnitude of the difference in the measured resistances at positive and negative currents of the first sensor is less than a magnitude of the difference in the measured resistances at positive and negative currents of the second sensor; and determining at least one of a fractional change in resistance and a scaled resistance for each sensor at each of the current levels, wherein the first and second sensors are independent sensors in an array of sensors formed on a common substrate.