How can a Rocking Chair Generate Electricity? Piezoelectricity.

By: Amanda Zheng


This summer I was tasked with a group of 4 other students to capture human kinetic energy. My first thought was: how am I possibly going to do that?! As a part of the New Jersey Governor’s School of Engineering and Technology, we began on the engineering process. Along with the expert help from a professor in Mechanical Engineering at Rutgers University, we explored the technology of piezoelectricity. Piezoelectric elements are often used as touch or vibration sensors such as the one pictured below.


However, they can also be used to generate a small amount of AC power under pressure due to a shift in the internal change centers which results in an external electric field.


During our research, we discovered that piezoelectric elements have been used in floor tiles by the company Pavegen and in research in shoes as a power source. Along the same line, we wanted to develop a new product that would be able to harness the full weight and pressure of a human being while also being a part of an application that can be done for long periods of time. After many rounds of brainstorming, we decided on a rocking chair. Yes, a rocking chair.


To clarify, when in a rocking chair, all of a person’s weight plus the weight of the rocking chair is concentrated on the bottom two curved legs. Also, it is a passive activity that can be done for hours (I could easily power through a season of Friends on one!).

Our design consisted of 20 piezoelectric disks along the bottom of the two legs which are wired in parallel to maximize for current (as piezoelectric elements do not produce much current). The power produced would charge a 3.7V lithium-ion battery which would then charge a USB output that could be used to charge numerous electronic devices.


The final product can be seen above! Long story short: the piezoelectric rocking chair works! Just very very slowly… like 0.01V/min slowly. Long story long: you can read our full research paper!


References:

[1] C. N. Kumar, “Energy collection via Piezoelectricity,” Journal of Physics: Conference Series, vol. 662, 2015.

[2] Nanomotion Ltd., “The Piezoelectric Effect,” Online, 2015.

[3] “Pavegen,” Online, 2019.

[4] Jana Tichy et al., Fundamentals of Piezoelectric Sensorics Mechanical, Dielectric, and Thermodynamical Properties of Piezoelectric Materials. Springer-Verlag Berlin Heidelberg, July 2010.

[5] American Piezo Ceramics, “Soft vs. hard ceramics,” Online, 2016.

[6] Elprocus, “Bridge Rectifier Circuit with Working Operation and Their Types,” Online, 2019.

[7] Clean Energy Institute, “Lithium-ion battery,” Online, 2019.

[8] Apple, “About Apple USB Power Adapters,” Online, 2019.

[9] Analog Devices, “Ltspice,” Online, 2019.

[10] Smart Machine Corp., “Energy Harvesting Engineering Services,” Online, 2019.

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