Piezoresistive Strain Sensors in Printed Photopolymer Composites: Percolation, Gauge Factor, Hysteresis and Fatigue

Piezoresistive strain sensing in printed photopolymer composites depends on a conductive network whose connectivity changes with deformation. The useful response is controlled not only by gauge factor but also by percolation position, hysteresis, baseline resistance and cyclic rearrangement of the filler network. Printing can impose anisotropic strain fields and geometric variation that alter the apparent electrical response. Qualification therefore requires resistance and strain to be measured together through loading, unloading and fatigue, with the initial network state preserved in the record. The resulting evidence supports three engineering decisions: a qualified strain and gauge-factor range, an acceptable filler-network and build-orientation state, and a fatigue threshold linked to baseline drift and recalibration. ER-378.