Microfabricated Inductive Micropositioning Sensor for Measurement of a Linear Movement

An inductive device with a moving core will change its inductance as a function of the core position. By extending this principle to a microtransformer with multiple evenly spaced cores, a measurement system combining features of analog (variable reluctance) and incremental positioning may be devised. For detecting the direction of motion system (to know in which direction to count), an incremental length-measurement system not only requires one, but two output signals, which have to be offset by 90deg. This paper presents a microtransformer-based positioning system fulfilling these requirements. It presents the fabrication technology employed and discusses experimental test results