Abstract: The invention provides a process for adjusting the friction coefficient and adhesion between a surface of a first solid object and a surface of a second solid object, which surfaces are movable with respect to each other when the solid objects are in contact with each other, wherein the surface roughness of at least one of the surfaces is adjusted by subjecting one or more selected parts of said first and/or second solid objects to an electric field and/or a magnetic field, wherein at least said one or more selected parts of said first and/or second solid objects comprise a piezo-electric material, and wherein other parts of said first and/or second solid object do not comprise a piezo-electric material. The invention further provides an object having a surface of which the roughness can be adjusted by subjecting one or more selected parts of the object to an electric field and/or a magnetic field, which selected parts comprise a piezo-electric material.