Konferenzbeiträge

A popular solution for force sensor applications is the integration of strain gauges in microelectromechanical systems. Before such a system can be used, it has to be tested and characterized. Typically, this requires a complete strain gauge integration within an electronic carrier such as ceramics in a pressure sintering process with a typical force of 5000 N acting on a 100 mm x 100 mm specimen, which is costly and mostly not available for laboratory scale investigations due to lack of pressure sintering furnace. To overcome this challenge, we describe a method for the SOI (Silicon-on-insulator) strain gauge integration in ceramics with a force of 3 - 25 N upon a 7 mm × 9 mm specimen. A leverbased pressure application tool for the 0.04 - 0.34 MPa pressure range was successfully employed for this purpose. Targeting a single process configuration of chip-on-ceramic, the reliability of the process results is studied in terms of mechanical stability and electrical connectivity of strain gauge. Finally, the integrated strain gauge is mounted to a 3-point test bench to demonstrate its functionality as a force sensor. The described simple and low-cost fabrication process of the order of € 100 is useful for sensors integration within ceramics, not only for research laboratories but also for industrial manufacturers.

In the forthgoing work on a device that enables subatomic resolved highly reproducible positioning, a first prototype is here presented. The entire positioning system including the actuator, sensor and guiding mechanism, is realized as a micro-electro-mechanical system (MEMS) on chip level, based on silicon-on-insulator (SOI) technology. A modular printed circuit board acts as the mechanical as well as the electrical contacting interface for the silicon chip. First variants of a linear positioning system comprising axisymmetric double parallel crank structure are investigated. Pivot joints as flexure hinges with concentrated compliance are deployed. These hinges show minimal rotational axis displacement for small angles of deflection, thus ensuring smallest deviations to a straight-line path of the linear guiding mechanism. An electrostatic comb actuator transmits forces contactless to minimize over constraints. A measuring bridge in differential mode utilizes the same comb structures to measure the table position based on the capacitance change. Estimating the position resolution, limited by the resolution of the capacitive sensor, a measurable step width below 50 pm can be expected. In further steps, the device will be a platform to be equipped with a lattice-scale-based position measurement system according to achieve an even higher resolution and reproducibility.