No abstract

Failure in dynamic structures poses a pressing need for fault detection systems. Interconnected sensor nodes of wireless sensor networks (WSN) offer a solution by communicating information about their surroundings. Nonetheless, these battery-powered sensors have an immense labor cost and require periodical battery maintenance and replacement. Batteries pose a significant environmental threat that is expected to cause irreversible damage to the ecosystem. We introduce a fully integrated vibration-powered energy harvester sensor system that is interfaced with a custom-developed fault detection app. Vibrations are used to power a radio frequency (RF) transmitter that is integrated with the vibration sensor subunit. The harvester-sensor unit is comprised of dual moving magnets that are bordered by coil windings for power and signal generation. The power generated from the harvester is used to operate the transmitter while the signal generated from the sensor is transmitted as a vibration signal. Transmitted values are streamed into a high precision fault detection app capable of detecting the frequency of vibrations with an error of 1%. The app employs an FFT algorithm on the transmitted data and notifies the user when a threshold vibration level is reached. The total energy consumed by the transmitter is 0.894 µJ at a 3 V operation. The operable acceleration of the system is 0.7 g [m/s2] at 5–10.6 Hz.

This article introduces an enhanced magnetic spring based energy harvester design suitable for harvesting kinetic energy from vibrations that are characterized by low acceleration levels. The presented design consists of a levitated magnet, an FR4 spring-guided magnet and coils. Prototypes of the enhanced harvester design are fabricated and characterized experimentally. For comparison, a traditional magnetic spring based vibration energy harvester is fabricated and characterized experimentally. Results from experiments confirm the superiority of the proposed enhanced harvester design over the traditional harvester design. At 0.1g [m/s2], the peak power of the enhanced harvester reaches approximately 40 times the peak power generated by the traditional harvester. At this acceleration level both enhanced and traditional harvesters exhibit approximately 0.4 [Hz] frequency bandwidth. At 0.3g [m/s2] the improvement in power generated by the enhanced harvester is approximately 400% compared to the power generated by the traditional harvester while the frequency bandwidth increases by 80%.

This article introduces an electromagnetic vibration energy harvester and sensor assembly that is interfaced with a monitoring app for risk assessment of dynamic structures. The stand-alone energy harvester subassembly is used to power an amplitude modulated (AM) radio transmitter and microcontroller circuitry that can wirelessly transmit vibration sensor data using a sensor subassembly. The dual-mass moving magnets of the electromagnetic energy harvester and sensor assembly incorporate a directed magnet by a diaphragm-like moving FR4 spring. The transmitted sensor values are streamed into a PC where signal processing of the data takes place. The designed app can identify the vibration frequency of the sensor with high precision with an error as low as 0.1%. The total energy consumed to transmit a sensor value is approximately 0.9 μJ at an operating voltage of 3 V and minimum operable acceleration of 0.7g [m/s2].