Embedded Pressure Sensing Metamaterials Using TPU-Graphene Composites and Additive Manufacturing

Abstract

Disabilities impacting mobility are a global concern requiring gait rehabilitation, where monitoring foot pressure distribution is fundamental. Wearable systems provide an alternative to stationary equipment eliminating space limitations. However, wearable sensors present challenges in the calibration, sensitivity, and human-sensor interface, requiring application-specific sensors. This study aimed to develop wearable sensors where the structural and material properties can characterise the sensitivity and range of measurement during the design phase. We developed wearable piezoresistive sensors using additive manufacturing to create mechanical metamaterials with embedded pressure-sensing capabilities. Three structural designs were developed for different measuring ranges (0 – 50 N, 0 – 100 N, and 0 – 150 N) using body-centred cubic lattices constructed via pyramid unit cells. In addition, two graphene infusion processes were evaluated. We analysed the influence of structural dimensions and the graphene infusion process on the piezoresistive response of the sensors. The measuring range was affected mainly by tuneable structural dimensions, while the infusion process influenced the piezoresistive sensitivity and the linear response. The outcomes in characterising the piezoresistive sensors based on structural and material properties could allow the development of wearables with embedded pressure sensing with a predictive response solely based on design parameters using additive manufacturing and graphene inks.