Additive Manufacturing of Controlled Porous Elastomeric Nanocomposites for Enhanced Sensing Function

摘要

Elastomeric sensors have a wide range of applications in fields such as structural health monitoring, robotics, and biomedical industries. The additive manufacturing of these sensors, achieved using Direct Ink Writing (DIW), has provided numerous advantages, including increased sensitivity and the fabrication of complex geometry. However, bulk material sensors manufactured additively or using conventional methods, display a more significant effect of hysteresis, especially at strains higher than 10%, which limits their sensitivity. They also show a higher level of material relaxation whereby the resistance change within the material decreases in cyclic loading of the same strain and strain rate. Sensors with significant amounts of porosity have decreased hysteresis and high sensitivity at the lower strain. Porosity can be introduced in the form of varying infill densities and patterns made possible by DIW, which reduces these bulk material effects. In this paper, a lattice structure with four infill densities are investigated, and the samples are 3D printed using a grid infill pattern. The fabricated samples are characterized using a scanning electron microscope (SEM) to validate the microstructural features and layer bonding. Each sensor’s pressure-sensing capability is investigated using cyclic compression loading at various maximum strains. Sensing experiments show an increase in strain sensitivity with the introduction in porosity, compared to bulk samples of the same material and geometry. It is found that introducing porosity using DIW is a sensible strategy to improve the piezoresistive performance of nanocomposites and to allow for the tunability of sensing capacity in piezoresistive strain sensors.