High temperature circular position sensor based on a giant magnetoresistance nanogranular Ag/sub x/Co/sub 1-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 (mu)V/V/((degree)). The operational temperature range of this sensor is -40(degree)C/+120(degree)C, although the magnetic film tolerates higher temperatures up to 200(degree)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.