What is the purpose of a bridge rectifier in a TENG-based energy harvesting system?

The purpose of a bridge rectifier in a TENG-based energy harvesting system is to convert the alternating current (AC) output of the TENG into direct current (DC). A TENG generates AC because the charge transfer and electrostatic induction processes reverse direction with each cycle of mechanical motion. However, most electronic devices and energy storage components, such as batteries and capacitors, require a DC power supply. A bridge rectifier consists of four diodes arranged in a specific configuration that allows current to flow in only one direction, regardless of the polarity of the AC input. This process, known as rectification, converts the AC waveform into a pulsating DC waveform. The pulsating DC output can then be further smoothed using filtering techniques, such as capacitors, to provide a more stable DC voltage suitable for powering electronic circuits or charging energy storage devices. Therefore, the bridge rectifier is an essential component for interfacing a TENG with electronic loads that require DC power. Without it, the alternating current produced by the TENG could not be directly used to power most devices.