Research and Development of a High-Resolution Inductive Measurement System (Micro Inductosyn®)

In this funding project, research, development and thin film production of a miniaturized, high-resolution, inductive displacement measuring system based on the Inductosyn® principle is carried out. In contrast to conventional Inductosyn®, displacement measurement is carried out using two pairs of meandering coils (Fig. 1 / Fig. 2). With four induced signals it is possible to correct not only the distance travelled and the direction of movement, but also the inaccuracies that could arise during the final assembly of the system. The desired air gap between the stator and rotor is 5-10 µm. To increase the coupling between the microcoils, a soft magnetic flux guiding system was integrated.

The desired interpolation accuracy of less than 0.1 µm makes the system a displacement sensor that is to be integrated into microtechnical components, used for the fine positioning of linear microactuators and for position measurement of microtables, microvalves and other microcomponents.

The distance measuring system was manufactured using thin-film technology in the clean room environment. The soft magnetic flux guidance as well as the meander coils made of Cu were electroplated. The electrical insulation between the flow path and the coil consists of Si₃N₄, which was deposited in a PECVD process. Fig. 3 shows a meander coil with poles.

The mounting device was manufactured from AlTiC ceramics by means of cut-off grinding. The air gap between the stator and rotor is defined by a 5 µm thick spacer foil.  Fig. 4 shows a representation of the mounting device.