In this paper we present the design and test of printed strain sensors, which can be integrated in light-weight
structures for monitoring purposes. We focus on composite structures consisting of metal substrate as well as
insulating and conductive ink layers for sensing normal strain at the surface. Both, inkjet and screen printing
technology are used to realize resistive topologies that can be evaluated using a Wheatstone bridge configuration.
In a first step, we analyze electrical properties of functional inks: electrical impedance and breakdown electrical
field strength in case of insulation inks, resistance in case of conducting inks. Silver and PEDOT:PSS based
suspensions are printed as sensing layer. To determine the resistance change due to plastic deformation of the
metal substrate, tensile tests are performed up to 30% strain and subsequent resistance change is measured. In
a second step, the sensing effect of printed conductive structures is investigated. Resistive sensing topologies
are designed for detecting longitudinal and transversal normal strain. Meander structures, which form single
resistors as well as bridge configurations, are printed on test specimens and analyzed in a four-point bending set
up. Performing loading and unloading cycles, gauge factor, cross sensitivity, nonlinearity and hysteresis error of
the sensors are measured.