High performance flexible piezoelectric pressure sensor based on CNTs-doped 0–3 ceramic-epoxy nanocomposites

Highlights: • Effects of CNTs on piezoelectric properties of the nanocomposite films were studied. • The d₃₃ and g₃₃ values of the film with 0.07 wt% CNTs were 68 pC/N and 434 mV·m/N. • The nanocomposite pressure sensors showed a good linear response up to 150 kPa. • The output voltage of nanocomposite with 0.07 wt% CNTs was 575.42 mV under 1 N. The high-content ceramic-epoxy nanocomposites for highly sensitive piezoelectric pressure sensor were fabricated using Pb(Zr_1/2Ti_1/2)O₃-(Pb(Zn_1/3Nb_2/3)O₃-Pb(Ni_1/3Nb_2/3)O₃) and epoxy resin with the contents of 81 and 19 wt% respectively. This paper represents the effects of multi-wall carbon nanotubes (MWCNTs) conductive filler on the electrical conductivity, dielectric and piezoelectric properties of the ceramic-epoxy nanocomposite films. Based on the percolation theory, it was revealed that small amounts of CNTs dispersed within the nanocomposite film can significantly improve the dielectric and piezoelectric properties of the film due to their features acting as conductive bridges between the piezoelectric ceramic particles. The fabricated flexible ceramic-epoxy nanocomposite film with 0.07 wt% CNTs had highest piezoelectric coefficients of 68 pC/N (d₃₃) and 434 mV·m/N (g₃₃), which are respectively 2.5 and 2.2 times higher than those of the preliminary nanocomposite film. Corresponding to the enhanced dielectric and piezoelectric properties of CNTs-doped nanocomposite films, it was also shown that the fabricated flexible piezoelectric pressure sensor can generate highly sensitive performance with the increase of CNTs below the percolation threshold. The flexible piezoelectric nanocomposite pressure sensor optimized with 0.07 wt% CNTs filler content provided the remarkably enhanced output voltage of 575.42 mV under 1 N.