Implementation and Testing of an Elastic Strain Powered Wireless Sensing System for Energy-Autonomous Applications

This paper presents implementation and testing of an elastic strain powered wireless sensing system for energy-autonomous applications. The system harvests strain energy from a vibrating structure and convert it into usable electrical energy for powering sensors and a wireless communication node. Typical in-flight vibration frequency and strain levels on the bottom side of the aircraft wing's root were investigated for testing the performance of the system. Major concerns of the implemented system are the amount of harvested power, in the usable range of milliwatts, and the low power consumption energy-flow management for data sensing and transmitting. Such results arise from the use of flexible piezoelectric macro-fiber composite (MFC) bonded as energy generator to both an aluminum and a composite substrate, and from the integration of a new Energy-Aware Interface (EAI). The harvested power is between 0.5-12 mW under low and non-resonant vibrations of 2.5-10 Hz and 480-1170 μstrain peak-to-peak. The waiting time between two consecutive transmissions was measured around 0.4 s under 1170 μstrain peak-to-peak excitation at 10 Hz. Such achievement shows strong capability to approach self-powered continuous monitoring. The system has potential of being used to harvest strain energy from the vibrations of aircraft in active service for powering an on-board wireless sensing node for Structural Health Monitoring (SHM).