Multi-Dimensionally Functionalized Pressure Sensor for Human Motion Detection Based on 1D AgNWs/2D rGO-Coated 3D Porous Sponge

This study presents a conductive-type pressure sensor based on a conductive composite of 1D/2D nanomaterials coated onto a 3D nonconductive polymer structure with various pores. A 3D porous elastomer for the substrate was fabricated by using a sugar template, which led to an increased mechanical deformation range. The sugar template enhanced the surface roughness of the polymer, resulting in an improvement in the adhesion of nanomaterials to the polymer surface. Subsequently, it was functionalized by coating with hybrid nanomaterials of 1D silver nanowires (AgNWs) and 2D reduced graphene oxide (rGO) through a dip-coating process. When pressure is applied, the rGO/AgNWs/ecoflex pressure sensor deforms along the direction of the applied force, causing the conductive multidimensional nanomaterials to come into contact. Consequently, the improved networks between the two nanomaterials expanded the current paths, increasing the current detected through the electrodes attached to the sensor. The rGO/AgNWs/ecoflex pressure sensor, with its porous structure within the flexible ecoflex, demonstrated a high sensitivity (up to 2.29 kPa^-1) over a wide detection range of 0-120 kPa. This enables the monitoring of a wide range of motions, including small pressures such as subtle touch, respiratory vibrations, and drinking, as well as large pressures such as human bodily movements, finger/arm bending, and foot pressure, making it an excellent candidate for applications requiring precise pressure detection.