CAREER: A Universal Microsystem-based Vibration Energy Harvester

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This project is jointly funded by the Electrical, Communications and Cyber Systems (ECCS) and the Established Program to Stimulate Competitive Research (EPSCoR). With the growing demand for the Internet of Things, Cyber Physical Systems, and Smart Buildings there will be a significant increase in wireless sensor networks, all of which will require power to operate. However, batteries have a limited lifetime, therefore there is a need to create a self-sustaining system that can harvest energy from the ambient environment without the need of batteries. Vibration-based energy harvesters have the advantage of functioning 24/7 and can be applied to almost all applications. Microsystems-based energy harvesters have advantages such as small-scale and low cost, but there are numerous challenges which have limited their success. This study will investigate methods to solve those challenges and overcome the limitations. The goal of this study is to create a universal low-frequency microsystem vibration energy harvesting system to power these wireless sensor networks. The investigated methods to solve these challenges have potential to be applied to other microsystem applications to enhance sensor or actuating performance in the future. The project will impact society as well as the scientific community. In addition, this project aims to increase awareness of microsystems through an interdisciplinary STEM education outreach program directed at undergraduate and K-12 students. The program will develop outreach events to promote microsystems and STEM education to underrepresented students. The study of microsystems is interdisciplinary consisting of all STEM disciplines. The educational goal of this project is to increase awareness of microsystems and how they impact our daily lives to inspire the next generation of scientists and engineers. Microsystem vibration energy harvesters have been extensively investigated over the past decade but limitations due to their micro-scale and mechanisms of actions have limited the systems from progressing past the lab environment. There are four grand challenges that currently limit their use: 1) narrow frequency bandwidth, 2) lack of frequency tunability, 3) low power density, and 4) reliability. This study will investigate and develop novel designs and microfabrication methods to address these challenges. The research objective of this project is to enhance functionality of a low frequency low acceleration piezoelectric microsystem energy harvester by combining novel integration and actuation mechanisms to i) widen the bandwidth, ii) perform wide range active/passive frequency tuning, and iii) enhance power density using novel functional thin film material structures. Each component will be designed and characterized individually and then integrated together to develop a complete universal system that can overcome the current challenges associated with micro-scale vibration energy harvesters. Non-linear dynamics mechanisms to widen the bandwidth without significant decrease in power using monolithically integrated movable proof-mass will be investigated. This will result in a passive wide bandwidth system that does not require any additional power consumption. Frequency tuning will be investigated using a novel mass load distribution method that can be passive to increase manufacturability of the devices and promote batch fabrication advantages of microsystems to obtain a universal low-frequency system for multiple applications (250 Hz). An active tuning mechanism based on mass load distribution with a targeted frequency range of 200 Hz with a resolution of 1 Hz will also be investigated. Power density will be enhanced by developing new polarity controlled piezoelectric structures by enhancing material properties of ternary nitride thin films. Integration of these methods to create a monolithic all-in-one system requires novel microfabrication methods which will be developed and can be applied to future microsystem applications beyond energy harvesters.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.