The invention relates to a piezoelectric sensor consisting of a base support (2), a piezoelectric measuring sensor arranged on said base support (2), a protective layer (3) covering the measuring sensor and an electronic evaluation system (4). The measuring sensor (1) is formed from a piezoelectric layer (1), the base support (2) has a first contact layer (5) which is electrically connected to the piezoelectric layer (1) and the protective layer (3) comprises a second contact layer (6) which is electrically connected to the piezoelectric layer (1). The electronic evaluation system (4) can determine a mechanical charge of the piezoelectric layer (1) by evaluating the difference of the electric potential between the first contact layer (5) and the second contact layer (6).