Ultrahigh Performance Sono-Piezoelectric Nanocomposites Enhanced by Interfacial Coupling Effects for the Implantable Nanogenerators and Actuator

Transcutaneous energy harvesting technology based on ultrasound-driven piezoelectric nanocomposites/nanogenerators is the most promising one in medical and industrial application. Based on ultrasonic coupling effects at the interfaces, interfacial architecture is critical parameter to attain desirable electromechanical properties of the nanocomposites. Herein, we successfully synthesized a core-conductive shell structured BaTiO 3 @Carbon [BT@Carbon] nanoparticles [NPs] as nanofillers to design an implantable poly(vinylidenefluoride-co-chlorotrifluoroethylene)/BT@Carbon [P(VDF-CTFE)/BT@Carbon] piezoelectric nanogenerators (PENGs) and actuators for harvesting ultrasound underneath the skin. Firstly, BT@Carbon NPs as heterogeneous nucleators can accelerate the crystallization rate of the nanocomposite and form small lamellae of crystals, which is beneficial for reducing the energy barrier of dipoles switching under ultrasound (US) stimulation. Secondly, a conductive carbon-shell interface between BT and P(VDF-CTFE) matrix is beneficial for charge generation, separation and transfer performance at the interfaces under US stimulation. Remarkably, P(VDF-CTFE)/BT@Carbon peizoelectric nanogenerators attain high tissue penetration up to ~5 cm in the pork and a maximum output power 626 μ W/cm 2 under ultrasound stimulation, which is far larger than that of force-induced PVDF-based nanogenerators. Finally, US-PENG sensing system, which is composed of an amplifier and a microcontroller, can efficiently convert ultrasonic energy to electricity and thus can switch on/off small electronics in the tissue. Our systematic findings pave a new avenue to develop for wireless power and actuators for medical implant devices.