Low-cost thick-film force sensors for the 100 N force range

This work presents calculations and measurements on a novel low-cost thick-film force sensor design for the 100 N force range. The mechanical concept of these force sensors is based on a double ring biaxial load, which allows the fabrication of simple sensors for a wide range of nominal forces (ca. 10 to 400 N) using standard thick-film alumina ceramic substrates of different thicknesses. Metal or laminate substrate materials allow even higher forces to be attained with this concept. Due to the relatively high stiffness of the substrate, the electronics can be integrated on-board and the sensor is relatively insensitive to parasitic stresses introduced, for instance, by the electrical connections. Measurements on sensors with different nominal forces are presented, and the potential sources of non-ideal behaviour are discussed. It is found that the accuracy is mainly limited by the degree to which clean boundary conditions can be guaranteed. Key words: thick-film force sensors, low-cost, double ring geometry