IOP Publishing Journal Title Journal XX (XXXX) XXXXXX https://doi.org/XXXX/XXXX xxxx-xxxx/xx/xxxxxx 1 © xxxx IOP Publishing Ltd Polycarbonate based multifunctional self-sensing 2D and 3D printed structures for aeronautic applications P. Costa 1,2* , J. R. Dios 3 , J. Cardoso 1,4 , J. J. Campo 3 , C. R. Tubio 5 , B.F. Gonçalves 1,6 , N. Castro 5 , S. Lanceros-Méndez 5,7** 1-Center of Physics, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal 2-Institute for Polymers and Composites IPC, University of Minho, 4804-533 Guimarães, Portugal 3-GAIKER Technology Centre, Basque Research and Technology Alliance (BRTA), Parque Tecnológico, Ed 2020, 48170 Zamudio, Spain 4-Institute of Science and Innovation for Bio-Sustainability (IB-S), University of Minho, Braga, 4710-057, Portugal 5-BCMaterials, Basque Center for Materials, Applications and Nanostructures, UPV/EHU Science Park, 48940 Leioa, Spain 6-INL-International Iberian Nanotechnology Laboratory, Braga, 4715-330, Portugal 7-IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Spain E-mail: *pcosta@fisica.uminho.pt; **senentxu.lanceros@bcmaterials.net Received xxxxxx Accepted for publication xxxxxx Published xxxxxx Abstract Different polycarbonate materials have been reinforced with carbon nanotubes to tune electrical conductivity and to induce piezoresistive self-sensing capabilities. Further, the composites were processed by solvent casting and fused deposition modelling (filament for 3D printing) methods. An electrical conductivity percolation threshold of ≈0.3wt.% has been found for solvent casted films, whereas samples processed by 3D printing show higher thresholds, ≈2wt.%, presenting all samples a similar maximum electrical conductivity (σ≈ 1×10 -3 S/m), thermal and chemical properties. Overall mechanical properties are larger for the solvent cast films concerning the 3D printed ones, particularly the elongation at break. The piezoresistive sensibility, obtained after 4-point-bending and uniaxial strain experiments, shows gauge factors up to 1.7, independently of the processing method. The functionality of the materials has been demonstrated by the implementation of an airplane wing section model with self-sensing capabilities. Two implemented strategies showed the suitability of the developed materials for real- time monitoring of the wing mechanical deformation. Keywords: Polycarbonate, piezoresistive, structural health monitoring, 3D printing, self-sensing. 1. Introduction Polymers and polymer composites have been increasingly investigated for the development and application of multifunctional lightweight materials for structures [1], including sensing and/or actuating properties [1, 2]. In particular, efforts on additive manufacturing of multifunctional polymer-based materials have largely increased in recent years for applications in structural health monitoring (SHM) in automotive [3], aeronautics [2, 4], biomedical (implants or prosthetics) [1, 4], electronics [3, 5] or even toy industries [1, 5].