A Wireless and Passive Strain Sensor With Improved Sensitivity Enabled by Negative Poisson’s Ratio Structure

The conventional magnetostrictive strain sensor suffers from low detection sensitivity. In this study, a wireless and passive magnetostrictive strain sensor with improved sensitivity was proposed, modelled, analyzed, and tested. A hollow plate with a negative Poisson's ratio structure was taken as the substrate, substituting this for the conventional positive Poisson's ratio material. An analysis model was established for the negative Poisson's ratio substrate. Finite element method (FEM) analysis was conducted to verify the negative Poisson's ratio model. Experiments were carried out to prove the sensitivity enhancement principle. Parametric studies were conducted to investigate the influence of the geometry dimension on the output of the electric signal. We show that the proposed sensor has an improved strain test sensitivity of up to 176.3%. The experimental results further indicate that different geometry dimensions of the negative Poisson's ratio have different influences on the sensitivity of the magnetostrictive strain sensor. The proposed magnetostrictive strain sensor shows the advantages of high sensitivity, easy implementation, convenient fabrication, and low cost.