This asymmetric accumulation of electric charges between the two liquid electrodes form the potential difference that drives electrons to flow from one electrode to the other through an external circuit. By exerting an alternate mechanical traction repeatedly, the back and forth movement of the electrification liquid induces a continuous alternating electric signal between the two ionic solution electrodes, generating a continuous alternating current through an external circuit.
Experiment showed that such a BSNG could achieve an open-circuit voltage over 170V in dry conditions and over 10V in a liquid environment. Next, the researchers used the current signal from several BSNGs affixed to a wet suit to monitor a swimmer’s strokes in water.
Recording the signals from BSNGs at elbow and knee joints, the authors were able to reliably detect different swimming strokes. They conclude such stretchable underwater bio-inspired nanogenerators could offer a sustainable power source for soft wearable electronics used underwater. Integrated in wet suits, the devices could also be used as sensors, to detect motion or tapping for the design of simple interfaces.