Mortise-tenon joint structured hydrophobic surface-functionalized barium titanate/polyvinylidene fluoride nanocomposites for printed self-powered wearable sensors

Self-powered wearable sensors exhibiting high sensitivity and flexibility have attracted widespread interest in the field of wearable electronics. Herein, a 3D printing technique was employed to fabricate a fully printed, flexible self-powered sensor with high piezoelectric performance. This printing technique is based on the hydrophobic surface-functionalized barium titanate (FD-BTO)/polyvinylidene fluoride (PVDF) composite film. To strengthen the interface bond between BTO and PVDF, the BTO nanoparticles were surface functionalized using hydrophobic 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFDTES). As a result, there was an increase in the content of the β-phase in the PFDTES modified BTO (FD-BTO) nanoparticle composite film. The 3D-printed self-powered sensor based on the optimum FD-BTO/PVDF composite film exhibited excellent sensitivity (61.6 mV kPa-1) with a piezoelectric coefficient (d33) of 69.1 pC/N, which is two-fold higher than that of the unfunctionalized BTO/PVDF counterpart. Additionally, the power sensor displayed excellent mechanical durability in the 20 000 cyclic force tests. In practice, the printed devices were used as a sports wearable device to monitor and analyze athlete motion, and a self-powered printed sensor array (5 × 5), which could effectively detect the pattern image of the external pressure input. The 3D-printed self-powered sensor demonstrated herein can contribute significantly to the applications and the development of printed electronic wearable devices.