Mechanical behavior of strain sensors based on PEDOT:PSS and silver nanoparticles inks deposited on polymer substrate by inkjet printing

• Biocompatible strain sensors were fabricated by inkjet printed and characterized.
• PEDOT:PSS ink and nanoparticle silver ink was used for conductive tracks deposition.
• A close correlation between the deformation and resistance change is verified.
• The gauge factor for silver-ink sensors is about 3.7, for PEDOT:PSS-ink is 1.

Recently, inkjet printing technology has received growing attention as a method to produce low-cost large-area electronics, sensors, and antennas on polymer substrates. This technology relies on printing techniques to deposit electrically functional materials onto polymer substrates to fabricate electronic components or sensing elements. In this paper, we applied an inkjet printed technology for the development and characterization of films on a polymer substrate aiming at giving design considerations for the optimization of strain sensors or printed electronics obtained by inkjet printing. Two inks were tested over a polyimide substrate, a water-based conductive polymer, PEDOT:PSS, and a silver nanoparticles ink. Their sensing capabilities were investigated under tensile conditions and various strain histories (strain ramp; cyclic loading-unloading tests; application of constant strain over prolonged time) aiming at highlighting the correlation between electrical response, applied strain, time and mechanical histories. Furthermore, the mechanical viscoelastic response of the substrate was investigated under similar strain histories interpreting the results at the light of the substrate deformational characteristics and evaluating its influence.