A MEMS actuator comprising a main body including a central portion, couplable to a substrate, and a peripheral portion, which, when said central portion is coupled to said substrate, is suspended over the substrate and comprises a deformable structure (35*), which at rest has a spiral planar shape, extends around the central portion, and forms a plurality of membranes arranged in succession; said MEMS actuator further comprising: - a plurality of bearing structures (38, 39), each bearing structure (38, 39) being fixed at the top to the deformable structure (35*) and laterally delimiting a corresponding cavity, which has a lateral opening facing the central portion of the main body and is closed at the top by a corresponding membrane, said corresponding membrane comprising a fixed part, fixed to the underlying bearing structure (38, 39), and a suspended part, which is laterally offset with respect to the underlying bearing structure (38, 39) and delimits at the top said lateral opening of the cavity; - for each bearing structure (38, 39), a corresponding piezoelectric actuator; and wherein the piezoelectric actuators are electrically controllable so as to cause, each, a deformation of the corresponding membrane, the deformation comprising a curving upwards of a portion of the suspended part, the curvings of the portions of the suspended parts of the membranes causing a rotation of the bearing structures (38, 39) around the central portion of the main body. said MEMS actuator further comprising: - a plurality of bearing structures (38, 39), each bearing structure (38, 39) being fixed at the top to the deformable structure (35*) and laterally delimiting a corresponding cavity, which has a lateral opening facing the central portion of the main body and is closed at the top by a corresponding membrane, said corresponding membrane comprising a fixed part, fixed to the underlying bearing structure (38, 39), and a suspended part, which is laterally offset with respect to the underlying bearing structure (38, 39) and delimits at the top said lateral opening of the cavity; - for each bearing structure (38, 39), a corresponding piezoelectric actuator; - a plurality of bearing structures (38, 39), each bearing structure (38, 39) being fixed at the top to the deformable structure (35*) and laterally delimiting a corresponding cavity, which has a lateral opening facing the central portion of the main body and is closed at the top by a corresponding membrane, said corresponding membrane comprising a fixed part, fixed to the underlying bearing structure (38, 39), and a suspended part, which is laterally offset with respect to the underlying bearing structure (38, 39) and delimits at the top said lateral opening of the cavity; - for each bearing structure (38, 39), a corresponding piezoelectric actuator; and wherein the piezoelectric actuators are electrically controllable so as to cause, each, a deformation of the corresponding membrane, the deformation comprising a curving upwards of a portion of the suspended part, the curvings of the portions of the suspended parts of the membranes causing a rotation of the bearing structures (38, 39) around the central portion of the main body.