nanogenerators

Nanogenerators are devices that convert mechanical energy into electrical energy at nanoscale, enabling compact power sources for small electronics. They typically rely on piezoelectric or triboelectric effects to generate electric charges in response to mechanical stimuli. The term encompasses piezoelectric nanogenerators (PENGs) and triboelectric nanogenerators (TENGs), which use different physical mechanisms to harvest energy from motion, vibration, or pressure.

In PENGs, mechanical deformation of piezoelectric nanostructures such as ZnO nanowires, BaTiO3, PZT, or PVDF leads to charge separation and current flow. In TENGs, two dissimilar materials come into contact and separate, producing a cyclic buildup and release of surface charges through triboelectric effect and electrostatic induction. Nanostructuring, large surface area, and flexible substrates improve electro-mechanical coupling and enable harvesting from diverse sources, including human motion and environmental vibrations.

Applications include self-powered nanosystems, wearable sensors, biomedical implants, environmental monitoring, and energy harvesting from ambient mechanical energy. Individual devices typically generate small power levels, often in the nanowatt to microwatt range, but arrays and energy storage can provide usable power for low-power electronics. Challenges include limited energy density, efficiency under real-world conditions, humidity sensitivity for triboelectric devices, durability, and integration with power management and storage systems. Ongoing research explores new materials, surface engineering, and device architectures to improve performance, reliability, and scalability, moving nanogenerators toward practical self-powered technologies.