Flexible Piezoelectric Harvester for Human Fingers: Measurements and Applications

This paper presents an extensive set of measurements and suitable consideration on human finger energy harvesting from a mechanically excited piezoelectric element. The actual interest in portable systems and the constant development of electronic devices operating with low power consumption has pushed the scientific research to investigate on systems capable of collecting energy from the environment around them: this topic is the so-called energy harvesting (EH). The EH technologies bring together all the techniques and processes that make it possible recovery, transformation, and accumulation of energy, even of small quantities, obtained from different sources in the environment (radio signals, heat, light, vibration, wind, etc.). In this scenario, mechanical vibrations are a viable solution for providing low power to electronic systems. In particular, in this work, we present a test analysis on a harvesting system composed by a 3D printer finger emulating the human behaviour and a piezoelectric strip to be applied in autonomous smart gloves. Here, the experimental results using a commercial flexible bimorph piezoelectric transducer are given when the strip is implemented on a moving 3D printed finger. Results have demonstrated that a single finger can produce an open-circuit alternate peak-to-peak voltage up to 35.1 V, generating a maximum energy around 5 µW.