A sensor device comprising a base substrate and first and second flux
concentrator fixedly attached to the base substrate. The first flux
concentrator and the second flux concentrator are positioned with their
proximal end regions facing and spaced apart, defining a gap
therebetween. A magnetic sensor element is positioned in the gap, the
sensor element moveable towards and away from the base substrate. The
sensor device has a first system to offset stray magnetic fields, a
second system to modulate the sensor element to detect KHz frequency, and
a third system to dither noise from the first and second flux
concentrators.