Energy harvesting from a piezoelectric slipper during walking

In this article, we study energy harvesting during human walking from a slipper that hosts a piezoelectric energy transducer. Specifically, we demonstrate the feasibility of energy harvesting when a human wearing a slipper without a heel counter walks on a treadmill. In contrast to other work, we focus on the bending of the slipper instead of the heel strike and foot pressure as an energy source. We analyze the deflection and electrical behavior of the slipper through video analysis and voltage output measurement, respectively. We observe the oscillation of the slipper after its toe-off and the effect of high harmonics on the slipper bending. Additionally, we predict the harvested power delivery to load resistances from the piezoelectric slipper using a model and compare it with the experimental results. We find that the harvested power increases and optimal load resistance decreases with walking speed.