Low-Cost Strain Gauge Integration in Ceramics for Force Sensor Applications

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.