Abstract: [Object] To provide a technology such as a piezoelectric coil having higher energy conversion efficiency. [Solving Means] A piezoelectric coil according to the present technology includes a coil-like core material and a plurality of band-like piezoelectric materials. The plurality of piezoelectric materials is helically wound around the core material so as to be alternately arranged along the core material.

Abstract: [Object] To provide a technology relating to a piezoelectric coil or the like capable of performing displacement sensing. [Solving Means] A piezoelectric coil with a sensor according to the present technology includes: a piezoelectric coil; and a sensor. The piezoelectric coil includes a coil-shaped core and one or more first piezoelectric members that are helical relative to the core, and is expandable and contractable in an expanding/contracting direction. The sensor detects a displacement due to expansion and contraction of the piezoelectric coil.

Abstract: [Object] To provide a technology such as a piezoelectric coil having higher energy conversion efficiency. [Solving Means] A piezoelectric coil according to the present technology includes a coil-like core material and a plurality of band-like piezoelectric materials. The plurality of piezoelectric materials is helically wound around the core material so as to be alternately arranged along the core material.