Design of the monolithic planar isotropic auxetic piezo-resistive sensor glove to detect human hand motion

Using auxetic structures in the piezo-resistive sensors area improves the sensitivity due to having a negative Poisson's ratio, and the implementation of these novel structures in real applications is a challenge. In this work, the planar isotropic auxetic (PIA) structure with constant Poisson's ratio was used to construct a wearable monolithic sensor glove for identifying the movements of human hand fingers. To manufacture the monolithic glove, a mold consisting of three parts, including the upper part, the bottom part, and the core, was designed and manufactured. The glove was molded as a monolithic piece using silicone RTV2. On the fingers of the upper mold, the PIA structures were designed to correspond to the upper side of the glove and coated with graphite powder to behave as an isotropic piezo-resistive linear sensor. The finger movement detection test was performed, and the sensing performance of the sensor glove was evaluated. The available commercial ABAQUS2021 software was used to simulate the deformation behavior of the glove fingers to investigate the effects of PIA structure on sensing performance in the boundary condition of finger movement. Two types of comparisons, including the comparison of conventional sensors with auxetic sensors and the comparison of mixed auxetic sensors with coated auxetic sensors for use in the field of sensor gloves, were investigated in detail.