Acrylonitrile butadiene styrene – carbon nanotubes nanocomposites for 3D printing of health monitoring components

In this paper self-sensing nanocomposite formulations made of acrylonitrile butadiene styrene and different loading (3, 5 and 10 wt%) of multi-walled carbon nanotubes have been produced and 3D printed via fused filament fabrication. The nanocomposites have been characterized from a rheological, mechanical, thermal and electrical point of view to assess the strain-sensing properties. All the samples show a piezoresistive behaviour and the electrical resistance changes when a stress is applied. The gauge factor, measure of the sensitivity, for ABS 3CNT, ABS 5CNT and ABS 10CNT are 11.36, 3.21 and 1.62, respectively. The ABS 3CNT samples have shown the best self-sensing performances with high sensitivity and this formulation has been used for producing a health-monitoring 3D-printed smart structure where the active material is placed locally in the structure. The 3D-printed structure itself is able to monitor the strain and hence the stress level to which is subjected with a gauge factor of 1.5. A finite element analysis helps to explain the reason for reduced sensitivity namely the placement of the sensing layer.