Performance-enhanced flexible piezoelectric nanogenerator via layer-by-layer assembly for self-powered vagal neuromodulation

Vagus nerve stimulation (VNS) has emerged as a promising device-based neuromodulatory therapy that is expected to replace part of the traditional drugs, to treat various neuropsychiatric, inflammatory-immune, and cardiovascular diseases. Thus VNS device modification to enhance function features and improve operation safety is of great significance for expanding clinical application. Herein, we design a self-powered VNS device based on piezoelectric nanogenerator (PENG) that is battery-free and can successfully harvest biomechanical energy from the carotid artery pulsation to stimulate the vagus nerve. Among them, the flexible PENGs are prepared through electrospinning and layer-by-layer assembly using poly(vinylidene fluoride-co-trifluoroethylene) [P(VDF-TrFE)]/BaTiO3 (BTO). Multi-unit PENG shows outstanding output performance due to more generation units and ameliorated stress distribution. The maximum instantaneous power density is superior to most devices prepared with the same raw materials. COMSOL simulation results prove the notable amelioration in stress distribution inside multi-unit PENG. When the self-powered VNS device releases electrical stimulation to the vagus nerve, the heart rate of the four canines decreased significantly. This work not only broadens the application scope of the flexible PENG for energy harvesting, but also puts forward the novel concept of PENG-based self-powered vagal neuromodulation system.