Improving Characteristics of Magnetoresistive Sensors for Non-Contacting Current Measurement and Low Field Sensing

Magnetoresistive sensors, have demonstrated very high sensitivity and easy integration in read-out electronic circuits for data acquisition and signal processing. These advances are driven by the inherent benefits of magnetoresistive sensors: high accuracy, high resolution, dynamics, reliability, energy efficiency, etc. Still, some challenges remain in continuously improving performance, especially when detecting low magnetic field values. In this contribution, various approaches for improving low field measurement with magnetoresistive sensors are discussed and results are analyzed. A critical review of the methods for improving low field performance and low current measurements are analyzed and two methods are demonstrated. One method focused through the development of an exchange biased anisotropic magnetoresistance bridge sensor demonstrator chip (sensitivity between 4-4.67.10-<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> mV/mA, detection limit 2 mA with integrated current trace and differential configuration. Another method relies on a multi-turn planar coil and a double differential magnetoresistive based detection system. The realized demonstration model is able to measure currents accurately up to 2 mA with a sensitivity between 15.62 to 23.19 mV/mA. It is demonstrated that the sensitivity of a MR-sensor is up to approximately 13 times higher compared to a single biased sensor. These advancements can be applied to MR chip optimized for low field applications such as precision electronics, and for integrating with Lab-on-a-chip technologies for biosensing applications. This research aims to optimize the development steps for an extremely sensitive magnetoresistive non-contacting sensor used as DC/AC current sensor or as magnetic field sensor.