HIGHLY ELECTRICALLY CONDUCTIVE NANOCOMPOSITES FOR STRAIN SENSING DEVICE IN STRUCTURAL HEALTH MONITORING

Chipless, passive and wireless sensors are one of the most important expected developments in wireless sensor technology for Structural Health Monitoring (SHM) because of their compactness and the absence of a battery or chip for the sensor operation. Strain sensitive resonant antenna reflectors based on the strain sensing metasurfaces (i.e. frequency-selective surfaces) are employed for this application. The variation of the spectral response of the metasurface with external perturbation results in an intrinsically effective sensing mechanism. Highly electrically conductive nanocomposites are required for this application. In this work, nanocomposites at high graphite nanoplatelets content (70 wt%) are fabricated by a spray deposition process on a polyetherimide (PEI) support. Experimental tests have been conducted to investigate the electromagnetic response of the material in the X band (8-12 GHz), showing an electrical conductivity of about 2.0 x 104 S/m. The design of the metasurface geometry and numerical simulations have been introduced that account for the electromagnetic properties of the material in the non-naturally frequency selectivity response under the mechanical strain in the X band