Direct-ink writing, in conjunction with Multi-Material (MM) Fused-Filament-Fabrication (FFF) was used to characterize the electrical- and piezo resistivity of silver-ink-based traces on top of thermoplastic polyurethane (TPU) substrate. Low resistivities were achieved, however at higher strains the silver resulted in a non-linear piezoresistive behaviour.
Even though silver ink was not deemed suitable for piezo-electrical sensing, the exhibited low resistivity can be used for conductive contact traces when combined with carbon-doped polymer FFF, as to realize 3D printed strain gauges.