Printed strain sensors in organic coatings: In depth analysis of sensor signal effects

This work reports on the characterization of the strain response of printed strain gauges particularly with respect to achievable gauge factors and associated spurious effects. In particular, three different effects are observed, first a set-in effect, which only occurs after production, second a nonlinear response that is more or less only visible without mechanical stabilizing top coating. Third and finally, a hysteresis behavior was found. We subsequently investigated the performance over an extended period of time, which revealed interesting and partially unexpected material properties of printed strain gauges made from silver and carbon. Both silver- and carbon-based strain gauges show a hysteresis behavior of the gauge factor and non-negligible nonlinear characteristics. Furthermore, the carbon-based sensors show a strong initial base line drift within the first 50-100 cycles. All three effects, namely hysteresis, nonlinear gauge factor and initial base line drift, are confirmed within their respective standard deviations.