Materials that transform mechanical energy (pressure) into electrical energy (charge) are called piezo materials. They are used i.e. in sensors to analyse their pressure or mechanical forces. The "piezo-effect" ("piezein" = Greek for to press) can be diverted: the inversed effect means to transform electrical energy into mechanical energy. This is made possible by piezoelectrical actuating. In how far the piezo-effect can be used in interlocking security systems like door or vehicle locks is being analyzed at the ISS.