Linearity Enhancement in Magnetostrictive Sensors Based on Substructure with Tunable Poisson's Ratio

Magnetostrictive sensors based on the inverse magnetostrictive effect offer the advantages of wireless passive operation and structural simplicity; however, achieving both high sensitivity and superior linearity remains a persistent challenge. This study presents a magnetostrictive pressure sensor incorporating a tunable Poisson's ratio (TPR) chiral auxetic honeycomb substructure, designed to linearize the stress response of the sensing material. A theoretical model linking substructure design parameters to sensor output linearity was derived and validated through finite element simulations. The fabricated substructure exhibited a stable negative Poisson's ratio (-1.278 to -1.213) within its elastic regime and a highly linear axial-to-transverse strain relationship (x = 1.214y + 0.113). The sensor achieved a calibration linearity of R² = 0.99745, a continuous linear force response up to 118.7 N while the corresponding voltage variation reached 10.75 mV, and a maximum hysteresis error of 5.495% over eight loading cycles. Bearing press-fit force monitoring experiments confirmed practical viability under industrial conditions, with R² exceeding at least 0.995 for dry assembly between multiple bearing types and maintaining R² > 0.994 under lubricated conditions. The proposed TPR substructure approach establishes a reference framework for linearity enhancement in inverse magnetostrictive force sensors.