Piezoelectric ceramics, when mechanically activated with pressure or vibration, have the capacity to generate electric voltages sufficient to spark across an electrode gap. Piezoelectric ceramics are frequently used in this capacity to ignite a fuel source in lighters, gas stoves and welding equipment.
Single-Layer Piezoelectric Generators
Two common applications of piezo generators are in the push button cigarette lighters and gas BBQ grills. In these applications, pressing a button causes a spring-loaded hammer to apply a mechanical force to a rod-shaped single-layer piezoelectric ceramic. As a result of the piezoelectric effect, the ceramic element produces a voltage that passes across a small spark gap causing the fuel source to ignite.
Electrical energy in a rod-shaped single-layer piezo generator is released very quickly, is very high voltage, and very low current. Piezoelectric ignition systems are small and simple, long lasting and require little maintenance.
Multilayer Piezoelectric Generators
Multilayer piezo generators consist of a stack of very thin (sub-millimeter-thick) piezoelectric ceramics alternated with electrodes. The electrical energy produced by a multilayer piezo generator is of a much lower voltage than is generated by a single-layer piezo generator. On the other hand, the current produced by a multilayer generator is significantly higher than the current generated by a single-layer piezoelectric generator.
Because they do not create electromagnetic interference, multilayer piezo generators are excellent solid-state batteries for electronic circuits.
Due to advancements in micro-electronic systems many consumer devices have decreased in size. Smaller electronic systems require less power to operate. As a result, solid-state multilayer piezoelectric generators have become a feasible power source for some applications.
Current applications for multilayer piezo generators are energy sources for munitions and wireless sensors, such as sensors that monitor tire pressure in automobiles.
The Future of Piezoelectric Generation
Single-layer and multilayer piezo generators are used in applications where batteries or direct electrical current is not available.
Recently, energy harvesting using piezoelectric energy generation has become the focus of much research. While we are very excited about the prospects of energy harvesting using piezoelectric ceramics, we do have concerns regarding the use of piezoelectric ceramics in large-scale energy harvesting.
Piezoelectric ceramics have limited energy outputs, and therefore are potentially cost-prohibitive to feasibly use in any large-scale energy harvesting application. On the other hand, use of multilayer piezo generators in smaller electronic devices with low power requirements offers a real opportunity for exploration.
For much more information on the applications of piezoelectric generators, please order our book: Piezoelectric Ceramics: Principles and Applications