Graphene nanoplatelet–nickel ferrite coated textile-based embroidered capacitive pressure sensor for wearable electronics application†

Abstract

In recent times, pressure sensors developed from e-textiles have gained tremendous attention due to their flexibility, comfort, real-time detection, and potential for long-term applications when integrated with monitoring devices. The current research focuses on designing a capacitive pressure sensor comprising a porous textile substrate for electrodes and a porous textile-based dielectric layer. A solution processing approach was used to formulate a graphene nanoplatelet/nickel ferrite (GNP–NiFe₂O₄) composite, and the dip-coating technique was utilized to coat the sensing layer on pure cotton and cotton–polyester fabric. The coated fabric was integrated as a dielectric layer above the interdigitated capacitor to observe the capacitance variation under applied pressure. Additionally, the effects of the volume percentage of GNPs in GNP–NiFe₂O₄ and the fabric type on the sensor performance were also considered. The highest sensitivity was obtained for the cotton/polyester textile coated with 10 wt% GNP–NiFe₂O₄. The proposed pressure sensor can reach the linear band in the range from 11 kPa to 100 kPa, making it suitable for pressure sensing in cases of physical impact. Furthermore, a large-area, wireless array of six pressure sensors has been fabricated from the optimized dielectric textile coated with GNP–NiFe₂O₄. The change in the pressure range due to multiple sensors can be monitored on a smartphone, enabling real-time applications in monitoring human body motion, human tactile sensing, or any external pressure in cases of gait or grip.