One-step method for printing strain sensors on GFRP: assessment of sensor pattern effect

This work has investigated the transfer of strain gauge patterns onto fibre-reinforced composites and their strain-sensing performance. Multiwalled carbon nanotubes (MWCNTs) and cellulose nanocrystals (CNCs) constitute the composition of the aqueous ink. The ink was transferred on the surface of a glass fibre-reinforced polymer (GFRP) composite in a one-step process using screen printing method. Two distinct geomatical configurations were printed: single line and conventional grid (consisting of 11 legs). The piezoresistive performance of the two strain sensors was investigated in tensile loading mode. The geometry of the strain sensors presented different characteristics for the piezoresistive behavior under tensile mode. At small strains, the single line configuration sensor was nonlinear and not sensitive enough to detect mechanical stimulus compared with grid configuration (GF=1.0). At the highest applied strain in the plastic region, however, single line configuration was much more sensitive (GF of 23.8 compared with 2.4 for the grid sensor). The methodology of the proposed strain gauge sensor attempts to eliminate the complex integration of external sensors, ensure compatibility with composite structures, and facilitate a novel manufacturing method. On the other hand, challenges to improve sensitivity (beyond 2) in elastic region and resolution are yet to be overcome. Thus, our current and future work focuses on improving the performance and quality of the transferred sensors.