Innovative Graphene-PDMS sensors for aerospace applications

For aerospace morphing and deployable applications, the use of PDMS-based sensors is crucial because they are characterized by easy application on large surfaces, light design, very large deformations, and durability in harsh environmental conditions. In this contest, the goal of the present work is to manufacture innovative, highly deformable, piezoresistive sensors, manufactured by using a simplified and scalable method for the applications on large-area, such as the airplane wings. To this end, an ad-hoc polymeric matrix was designed by crosslinking Polydimethylsiloxane (PDMS) oligomers OH terminated with siloxane domains, obtained from hydrolysis and condensation of tetraethyl orthosilicate (TEOS). In particular, the solution of siloxanes domains precursors contributes to lower the viscosity without any solvents and to create, after curing, a fine crosslinked system which could withstand high deformation. Nanocomposites with graphene (6 - 15 wt%) were prepared by dispersing the filler into the polymeric precursor by adopting both magnetic stirring and sonication. Regardless the dispersion method and the filler concentration, few-layers of graphene coexists with large aggregations, and the electrical conductivity and the Gauge Factor increase as the graphene content increases. It was found that the graphene filler tends to hinder the evaporation of solvents developed during the crosslinking reactions, generating porosity and enhancing conductivity. A better filler dispersion obtained through sonication reduces the conductivity. All nanocomposites show a good linear relationship between the strain and the relative electrical resistance change, since the non-linearity remains below the 5%, and quite no-drift can be observed in a wide operative range