Acceleration sensor with oppositely-polarized piezoelectric plates

A testable acceleration sensor comprising

• a base (3);
• at least one piezoelectric element (1), mounted on said base (3), and formed as a sandwich structure of at least two piezoelectric plates (2) superposed on each other and having respective opposite polarizations, and an intermediate solid layer (10) mechanically interconnecting said plates;
• and
• at least two electrodes (9) applied to each of first and second lateral portions (11a, 11b) of said piezoelectric element;
• wherein,
• said lateral portions (11a, 11b) are electrically isolated from each other by an air gap (13) but are mechanically coupled to each other by a mechanical bridging means (12);
• and
• the sensor is testable by applying an electrical voltage to electrodes on said second lateral portion (11b), thereby causing a bending deformation of said element (1), said bending deformation giving rise to a test signal which is detectable at electrodes (9) on said first lateral portion (11a).