Optimizing piezoresistivity in SiTiOC through modulus-tunable Re-entrant structures

Piezoresistive ceramic materials have significant advantages in terms of high sensitivity and stability, but their inherent high stiffness limits macroscopic deformation and detection range. Modulus-optimizable SiTiOC re-entrant structures have been presented to enhance the detection limit of piezoresistive polymer-derived ceramic (PDC) through geometric adjustments, and the relationship between piezoresistive performance and structural geometric parameters was investigated. By modifying the inner folding angles of 30°, 45°, 60° and fix-connected, the deformation behavior and mechanical performance of the structures can be flexibly controlled, resulting in variable sensing properties with a highly sensitive load range tuned from 30 to 100 N. The SiTiOC material obtained showed an optimized sensitivity coefficient of 0.14 MPa⁻¹, which was attributed to an innovative modification of SiOC ceramics by introducing 2 wt% titanium acetylacetonate, creating impurity carrier accumulation regions and evenly dispersed conductive phases, forming percolation networks. Furthermore, the SiTiOC re-entrant structures exhibited long-term cyclic stability, maintaining a steady signal output under different loading degrees and frequencies. This was attributed to the excellent mechanical performance of the structures, with a high compressive strength and energy absorption value reaching 32.6 MPa and 125.44 kJ m⁻³, respectively, which ensured sufficient load-bearing capacity and the preservation of internal percolation networks. This study demonstrates the effectiveness of piezoresistivity tuning in PDC structures through geometric adjustments, thus expanding their application range. The one-step manufacturing of structuralized sensing materials by 3D printing provides a straightforward approach for the customized design of piezoresistive devices.