Printed Strain Gauges Embedded in Organic Coatings

Abstract In this work we present a method for the fabrication of all-printed strain gauges on pre-coated sheet steel substrates. The state of the art is to glue strain gauges on foil onto a substrate. This, however, has inherent disadvantages in terms of force coupling from the surface strain within the bent substrate to the glued strain gauge sensors. The fact that the glue and the strain gauge substrate have in general different moduli of elasticity affects the maximum achievable gauge factor of the final sensor stack. The method presented in this work circumvents these problems completely by removing the glue and the substrate layer from the stack and by printing the sensor layer directly on top of the pre-applied organic coating. We present comparative measurements of carbon black based sensors, as well as two different polymeric silver ink based sensors.