SWCNT thin film enabled piezoresistive sensors - Fabrication, characterization and application for structural health monitoring for polymeric composites structure

With the quantitative carbon nanotube dispersion characterization methods (preparative ultracentrifuge method (PUM) and dynamic light scattering (DLS)) and the spray-coating technique, the processingstructure-property relationships of single-wall carbon nanotube (SWCNT) thin film piezoresistive sensors were studied. It was found that the gauge factor of the sensors for a small tensile deformation (less than 2% strain) is close to unity and showed negligible dependence on the film thickness and SWCNT bundle length (L) and diameter (d). With incorporation of a small amount of conducting polymer - poly (3, 4- ethylenedioxythiophene)-poly (styrenesulfonate) (PEDOT: PSS) into SWCNT network, the SWCNT/PEDOT: PSS hybrid thin film sensor showed significantly improved gauge factor and electrical conductivity. The spray coating technique was further developed into a roll-to-roll process for continuously fabricating SWCNT thin film enabled fiber sensors. A promising application of the fiber sensor for real-time monitoring the curing process of epoxy resin has been demonstrated.