Integration of multiple bubble motion active transducers for improving energy-harvesting efficiency

In energy-harvesting systems that collect energy from waste micromechanical energy, the integration of multiple systems is essential to improve the total harvesting energy. However, we found that a simple integration of multiple systems does not work in water–solid electrification systems working in water, such as bubble motion active transducers (BMATs), unlike their use for typical triboelectric nanogenerators. The difference comes from the presence of water, which acts as a conductor and increases the total capacitance in the electrode with the increase in the number of systems, reducing the electrification efficiency. We systematically investigate the underlying mechanism and suggest a method to integrate multiple BMAT systems without losing energy by introducing an individually rectified multi-electrode (IRME) circuit. The rectifiers in IRME provide two functions: the usual rectifier function and an isolation function that disconnects neighboring electrodes. We demonstrate that the IRME BMAT improves the energy harvesting efficiency by a factor of the number of integrated electrodes, and that the system connecting ten electrodes works well as a power source to light an LED brightly in-situ. This method provides a promising path to the development of actual BMAT applications.