Inkjet printed resistive strain gages on flexible substrates

Abstract

In this paper, resistive strain gages designed and fabricated in inkjet printing technology with three different silver nanoparticle inks are presented. Inks have different Ag content (15, 20 or 25 wt%) and solvents (water type or organic type). Strain gages were printed on a 50 ?m thick polyimide and 140 ?m thick PET-based substrate with different printer types (professional and desktop). All printed sensors have the same size (17 mm ? 5 mm). To determine the change of resistance due to bending of the steel beam, tensile tests were performed up to 1500 microstrains. Due to performed cycles of loading and unloading of the steel beam, gauge factor and stability of the response of the strain gages are measured. Resistance change was measured with Keithley SourceMeter 2410. For acquisition of measured data, in-house software tool was developed. Measured gauge factors of the sensors are in the range between 1.07 and 2.03 (depending on a used ink, substrate and printer). Results of this research indicate the strain gages with good GF can be produced even with low-cost equipment, such as desktop printer EPSON C88+ and PET-based substrate.