Residential Piezoelectric Energy Sources
The Home Depot Smart Home is going to have a large number of sensors and microelectronic devices located throughout the house. These devices will need a clean, reliable source of energy that won’t need constant maintenance. The goal of this project is to utilize piezoelectric energy sources to provide power to certain applications in the house. Initially the plan was to create an energy scavenging floor that used piezoelectric transducers to harvest wasted energy in the foot strike of a human being. In consideration of the high cost and minimal power output of these piezo-sources, it seems more feasible to create small, localized energy sources rather than one large unified system. This idea has lead to several potential applications. The first is to combine a piezoelectric power source with sensors such that there would be no need to ever change the batteries in these sensors. The next application is to use piezoelectric cable throughout the floors of the house as a means of tracking. The final application is to combine piezoelectrics with a device to eliminate vibrations in household appliances.
Piezoelectric materials exhibit the unique property known as the piezoelectric effect. When these materials are subjected to a compressive or tensile stress, an electric field is generated across the material, creating a voltage gradient and a subsequent current flow. This effect stems from the asymmetric nature of their unit cell when a stress is applied. As seen in Figure 1, the unit cell contains a small positively charges particle in the center. When a stress is applied this particle becomes shifted in one direction which creates a charge distribution, and subsequent electric field. These materials come in several different forms. The most common is crystals, but they are also found as plastics and ceramics.