Strain gauges — Volume embedding vs. surface application

We present a strain gauge, which is directly embedded in a tensile test specimen made out of epoxy resin for minimal stress invasive embedding. Reducing the stress due to the embedding process is done by fabricating the sensor on a substrate which has approximately the same mechanical and thermal characteristics as the epoxy resin. We will show that strain gauge shows higher sensitivity it it is embedded in the specimen, compared to be placed on the specimen with adhesive. It is our goal to transfer these results from epoxy resin to other materials like steel, aluminum, carbon fiber reinforced plastics or elastomers and integrate sensors in these materials.