Additive fabrication of pressure sensitive material for flexible pressure sensor and its characteristics

The increasing interest in wearable devices and healthcare has sparked significant advancements in the development of flexible sensors for various applications. In this study, we present the fabrication and characterization of a flexible pressure sensor utilizing a three-dimensional structure of pressure sensitive material, fabricated through a layer-by-layer process. The aim of this research is to investigate the electrical response characteristics of the sensor based on the number of layers in the pressure sensitive material, both under static and dynamic pressure conditions. The pressure sensitive material, consisting of multi-walled carbon nanotubes (MWCNTs) dispersed in polydimethylsiloxane (PDMS), exhibits positive piezo-resistive properties. The flexible pressure sensor was fabricated using direct ink writing (DIW) technology, which enables precise control over the arrangement of the material. We explored the influence of layer configurations on the sensor's initial resistance and electrical resistance changes by varying the number of layers. Our experiments demonstrated a clear trend, indicating that as the number of layers increased, both the initial resistance and electrical resistance change decreased. This behavior can be attributed to the enhanced connectivity among carbon nanotubes within the material, resulting in reduced overall resistance. In addition to static pressure testing, we conducted dynamic pressure experiments to assess the sensor's response under rapidly changing pressure conditions. Our findings suggest that by manipulating the number of layers in the pressure-sensitive material, the sensor's sensitivity and detection range can be tailored to suit specific applications. This approach offers a flexible and unified method for fabricating sensors with diverse response behaviors within a single manufacturing process.