Additive Fabrication of Hybrid Carbon Nanotube Composite for Piezoresistive Pressure Sensor and its Properties

The growing demand for wearable electronics and healthcare solutions has driven significant interest in developing flexible sensors for various applications. This study presents the fabrication and characterization of a flexible piezoresistive sensor utilizing a three-dimensional structure of pressure-sensing material with distinct rheology deposited through a layer-by-layer approach. The research investigates the electrical response properties of the sensor as a function of the number of layers in the pressure-sensing material under static and dynamic loading conditions. The hybrid pressure-sensing material, composed of multi-walled carbon nanotubes (MWCNTs) and silica micro-powder (SiO2) dispersed in ecoflex, exhibits positive piezoresistive properties. The direct ink writing (DIW) technology featured precise control over material arrangement for sensor fabrication. We realized the effect of layer configurations on the sensor’s initial resistance and changes in electrical resistance by varying the number of layers. Our experimental results reveal a clear trend: as the number of layers increases, the initial resistance and the change in electrical resistance decrease. This trend is attributed to improved conductivity (1 Sm−1) of the carbon nanotube-based hybrid composite, reducing overall resistance. Along with static pressure tests, we performed dynamic pressure tests to evaluate the sensor’s response to abrupt pressure changes. Our results conclude that varying the number of layers in the pressure-sensing material can effectively tailor the sensor’s sensitivity and sensing range for specific applications. This technique offers a cost-effective, flexible, and integrated method for fabricating sensors with diverse response characteristics within a single-step manufacturing process.