High temperature circular position sensor based on a giant magnetoresistance nanogranular AgxCo1-x alloy

A new circular position sensor based on giant magnetoresistances has been developed. The sensing film is an AgCo nanogranular thin film patterned in a circular Wheatstone bridge configuration. This alloy shows a high magnetoresistance (8%) at room temperature within the field generated by an NdFeB permanent magnet that provides a sensitivity of 440 μV/V/(°). The operational temperature range of this sensor is -40°C/+120°C, although the magnetic film tolerates higher temperatures up to 200°C. These parameters and the contactless way of sensing make this device appropriate for automotive applications. The developed sensor presents excellent characteristics for life, since it is not sensitive to pollution; it is frictionless and does not present any type of electrical noise generated by contacts.