Piezoelectricity is the ability of some materials to generate an electric potential in response to applied mechanical stress. This may take the form of a separation of electric charge across the crystal lattice. If the material is not short-circuited, the applied charge induces a voltage across the material. The piezoelectric effect is reversible in that materials exhibiting the direct piezoelectric effect (the production of electricity when stress is applied) also exhibit the converse piezoelectric effect (the production of stress and/or strain when an electric field is applied).
The direct piezoelectric effect: electric field as a functionof stress. E: electric field, g: piezoelectric coefficients, σ: stress.
The converse piezoelectric effect: strain as a function of electric field. x: strain, d: piezoelectric coefficient, E: electric field.
The effect finds useful applications such as the production and detection of sound, generation of high voltages, electronic frequency generation, microbalances, and ultra fine focusing of optical assemblies. It is also the basis of a number of scientific instrumental techniques with atomic resolution, the scanning probe microscopies such as STM, AFM, SNOM etc, as well as more mundane uses including acting as the ignition source for lighters.
In a number of MEMS applications, piezoelectric materials offer several advantages over other principles like piezoresistive and capacitive technologies:
Published April 22, 2010