High force 10 kN piezoresistive silicon force sensor with output independent of force distribution

A silicon force sensor is realized in which the force is measured by compressing a meander shaped polysilicon strain gage. A second gage which is not loaded, is used for temperature compensation, for compensation of bending and stretching stresses in the chip and for common changes in zero load resistor values. It is shown that the output of the bridge is a linear function of the force and is independent of the force distribution on the chip. By measuring the resistance change along both gages, the force distribution on the chip can be determined so that it can be detected whether the sensor has an oblique load or not. The production process of the chip is simple and robust. A package is designed to apply the load. Results on hysteresis experiments are performed at four temperatures between 25 °C and 47 °C. The hysteresis measurement at room temperature is in close agreement with finite element calculations. The maximum hysteresis error is within ±0.14 % of the full-scale output (fso). Creep was tested by loading it five times. It follows that creep is smaller than 0.01 % of the fso. The total error including the interpolation error is within ±0.23 %.