Triaxial ball-impact piezoelectric converter for autonomous sensors exploiting energy harvesting from vibrations and human motion

Year: 2015

Authors: Alghisi D., Dalola S., Ferrari M., Ferrari V.

Autors Affiliation: Univ Brescia, Dept Informat Engn, I-25123 Brescia, Italy; INO CNR, I-25123 Brescia, Italy.

Abstract: A piezoelectric converter for energy harvesting composed of a rigid ball enclosed among six piezoelectric diaphragms arranged in a cube-shaped structure is presented. When the converter is excited by mechanical vibrations, the ball repeatedly bounces and hits one or more diaphragms, implementing the impact technique in a multi-degree-of-freedom configuration. The structure is isotropic thus the converter is effective irrespective of the vibration orientation. The converter is particularly suitable for energy harvesting from low-frequency random vibrations, such as those provided by human motion. The triaxial ball-impact piezoelectric converter was designed, built and experimentally characterized in the laboratory, and then tied to the ankle of a person and tested during physical activity. While the person is running at 7 km/h, a peak instantaneous power of up to 16 mW is provided by each of the six piezoelectric diaphragms, while the average power is significantly lower. The converter was coupled to a tailored power management circuit which intermittently powers a battery-less wearable temperature sensor module. In about 260 s of walking at 2 km/h, an energy of 1.4 mJ is extracted, stored into a 1-mF capacitor, and used to power the sensor module, which performs a temperature measurement and transmits the data to a receiver through a 433-MHz RF-UART link. (C) 2015 Elsevier B.V. All rights reserved.581

Journal/Review: SENSORS AND ACTUATORS A-PHYSICAL

Volume: 233      Pages from: 569  to: 581

KeyWords: Energy harvesting; Piezoelectric converter; Multi-degree-of-freedom converter; Triaxial converter; Ball impact; Frequency-up technique; Autonomous sensor
DOI: 10.1016/j.sna.2015.07.020

Citations: 45
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