Self Powered Systems
Overview of the Project

Project Objectives:

• Develop a novel device that harvests ambient vibration energy.

• Prototype, test and evaluate the design.

• Consider implications of developing device in the micro scale.

General Overview:

The team set out to harvest energy that is readily available for use with wireless sensors on a MEMS scale.  The team found vibration to be the optimal choice as opposed to radio frequency, light and thermal energy (see Fall report p18).  Further research then yielded three methods to capture vibration energy: electromagnetic, electrostatic and piezoelectric.

Electromagnetic energy harvesting uses the laws of induction by use of a magnet inside of a coil traveling along the axis of the coil to induce a voltage.  An electrostatic energy scavenging device uses the effect of changing capacitance between two combed structures to create an electromagnetic force.  The piezoelectric method is based on the material property of certain ceramics that produce a voltage when subjected to a stress.

Models for each of the concepts was created and was used for the final selection of the concepts.  Also taken into consideration is the manufacturability of each device, possible interference of device with any adjacent systems and other possible requirement (for example, an external voltage source).  The team decided on a piezoelectric beam to be the energy scavenging device to be developed.

The energy that was available to be harvested was also researched.  With the help of Sam Kouristas of Vibration Mounting, Inc. the team was able to find the frequency and amplitude of ambient vibrations found in a common office building's HVAC duct.  This environment was the target specifications this team will design the device around.

Data collection and research of initial designs were completed in the Fall of 2005.  Analytical models have been developed for the theoretical performance of the team's device.  During the Spring semester, the team will be working with fabrication and testing of the meso-scale prototype.  The design will be evaluated and optimized for a high energy density (voltage per volume).  Once completed, the transition from meso to MEMS scale will be studied.

For more information, please click the following links or download the final Fall report under the Documents section.

[Device Environment] [Concept Selection] [Test Setup] [Final Design] [Results]

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