Analysis of Magnetoresistive Sensors for Nondestructive Evaluation

Magnetoresistive (MR) sensors are trending in the industry due to their ease of use and their capability of maintaining the signal under investigation without destruction. MR sensors usually offer a reliable measurement of the change in magnetic field. With an understanding of the relationship between variation in magnetic field and the parameter under investigation, many parameters can be measured such as eddy currents or stray fields. This requires post signal processing as well as understanding of how to relate the quantity measured with what is required. However, MR sensors can measure DC and AC signals of frequency up to hundreds of MHz. This paper characterizes different MR sensors commercially available and discusses how they can be employed for non-destructive applications in the industry. MR sensors are found to exhibit high sensitivity up to 1005 mV/V/mT with small hysteresis of about 3 % for TMR sensors.