| abstract |
A displacement sensor (10) is provided with a long and rectangular elastic body (20). A piezoelectric element (30) is attached to the first main surface of the elastic body (20). The piezoelectric element (30) is provided with a long and rectangular piezoelectric sheet (300), and electrodes (301, 302), which are formed on both the main surfaces of the piezoelectric sheet (300). The piezoelectric sheet (300) has a poly-L-lactic acid as a material, and is at least uniaxially stretched. The piezoelectric element (30) is attached such that the uniaxial stretch direction of the piezoelectric sheet (300) forms 45° with respect to the longitudinal direction of the elastic body (20). When the elastic body (20) is bent in the longitudinal direction, the piezoelectric sheet (300) stretches in the longitudinal direction, and the piezoelectric element (30) generates a voltage of a predetermined level. |