Electrically Conductive 3D-Printed Piezoresistive Metastructure Lattice Sensors

Uniaxial compression and electromechanical force-sensing characterization were performed using a CellScale UniVert micromechanical tester equipped with a 200 N load cell. For mechanical characterization, pristine and coated lattice cubes (including topology-screening prints and optimized tetra lattices) were compressed under ambient conditions while recording force and displacement; the paper reports recording displacement over time in response to a controlled applied-force ramp (0.2 N/min) and computing lattice stiffness from the force–displacement response (n=3). For sensor characterization, the UniVert applied controlled static and dynamic compressive forces while electrical resistance changes were recorded: TiC-coated lattices were instrumented with conductive copper plates (25×25 mm) bonded to opposing faces using conductive silver epoxy (cured at 125°C for 60 min), wired into an external Wheatstone bridge/DAQ, and tested both as free-standing lattices and as lattices embedded within a solid elastic block; the setup isolated metallic tester connections with nonconductive tape to prevent electrical interference. oCVD PPy-coated lattices were similarly tested under UniVert-applied static and cyclic compressive forces using attached electrodes/copper tape. Dynamic loading experiments included low-force cycling down to 0.2 N and higher-force cyclic regimes (tens of newtons up to ~90 N) with frequency variation (reported 0.2–2 Hz in the study), enabling quantification of repeatability and drift under gait-relevant conditions.