The nanogenerator is a technology that converts micro- or nano-scale mechanical energy (e.g., biomechanical energy, ultrasound waves) into electricity. A nanogenerator utilizes nanostructured functional materials as building blocks to generate electricity from physical displacement via the piezoelectric or triboelectric effect. Human body is a rich source of biomechanical energy. In particular, many regular body motions, such as muscle stretching, breathing, heart beating, blood pressure fluctuation, etc. provide versatile selections for energy harvesting by nanogenerators. These electrical signals contain rich biological signals and can be used for physiological monitoring and electrical therapy.