Background

Energy Harversters utilize the ambient vibration within an object and convert it into electrical energy which provides autonomous power sources, and eliminates the need for external power sources from batteries. Energy harvesting technologies are commonly used in Structural Health Monitoring (SHM). SHM is used to detect damage in existing civil structures. One type of harvester currently on the market is cantilever‑based Piezoelectric Vibration Energy Harvesters (PVEH) which demonstrate an excellent conversion efficiency. However, challenges arise when using this approach as there is a poor response to all frequencies of vibration other than their own resonant frequency. One way to address this challenge is to enable tuning of the resonant frequency of the harvester closer to the ambient vibration frequency. To attain this, researchers have used polymer piezoelectric materials with a beating mechanism, have worked with using magnets in order to increase bandwidth, and worked with different configurations by stretching and straining. However, all of these designs do not tune the frequency range, and therefore; still pose shortcomings. There is a need for the ability to tune to different values matching with the ambient frequency to be employed by a broad scope of applications.

Technology Overview

The piezoelectric vibration energy harvester (PVEH) is a new type of technology that uses piezoelectric materials to convert vibrational energy into usable electrical energy. The PVEH is able to operate at low frequencies, down to less than 1 Hz, and can be easily tuned to different frequencies using the power it generates. The PVEH is made using a combination of piezoelectric and Ionic Polymer Metal Composite (IPMC) materials. 

The piezoelectric material, often a Macro Fiber Composite (MFC), is used to harvest energy, while the IPMC provides device tuning over a wide frequency range. MFCs are flexible, environmentally sealed, and can be easily bonded to surfaces, making them ideal for use in PVEHs. However, MFCs can only generate power at their resonant frequency, so the use of IPMCs is necessary to provide active tuning. IPMCs are compact, lightweight, and require very little power to operate. 

They consist of a fluorinated ion exchange membrane, such as a Nafion membrane, sandwiched between two electrodes. When a low voltage is applied, the positively charged ions in the membrane are repelled by the anode and move to the negative electrode, causing the membrane to bend. This bending can be used to vary the load on the PVEH, allowing it to be tuned to different frequencies.

The PVEH is typically configured as a cantilever, with one fixed end and one free end, but other configurations are also possible.

This wall-mounted device is a structural health monitoring and energy-generating technology that adheres to the exterior of buildings, providing a comprehensive analysis of the structure’s well-being while harnessing energy. 

Benefits

• Provides a net power gain.
• Ability to tune over a wide vibrational frequency.
• Resonant frequency shifts to different values effectively and efficiently.

Applications

• Structural Health Monitoring

Opportunity

• Collaborative research
• Licensing