A variable area capacitor device (4; 6; 8; 9; 10; 11; 12; 13; 14; 15; 16; 17; 18; 19; 21; 23; 23B; 25; 25B; 28; 30'; 40'; 50'; 60') for a microelectromechanical system, the device comprising a first electrode (41; 61; 81; 91; 101; 111; 121; 131; 141; 151; 161; 171; 181; 191; 211; 231; 251; 281; 31'; 41'; 51'; 61') and a second electrode (42; 62; 82; 92; 102; 112; 122; 132; 142; 152; 162; 172; 182; 192; 212; 232; 252; 282; 32'; 42'; 52'; 62') which are movable relative to one another along a given direction of displacement (d), the first electrode having a first free surface and the second electrode having a second free surface substantially parallel to the first surface, part of the first surface being superimposed on part of the second surface, the first surface being laterally delimited by a first edge (b 11) and a second edge (b 21) which are rectilinear and not parallel to each other, in the part where it is superimposed on the second surface, the second surface also being laterally delimited, in the part where it is superimposed on the first surface, by a first edge (b 12) and a second edge (b 22) which are rectilinear and not parallel to each other and which, in a projection onto the first surface, intersect respectively the first edge (b 11) of the first surface and the second edge (b 21) of the first surface, characterised in that the device comprises an additional electrode (193; 213), integral with the first electrode (191; 211) and having an additional free surface which is substantially parallel to the second surface and which is partially superimposed on the second surface, the additional free surface being complementary to the first free surface, at least: - in the vicinity of a first overlap point where, in a projection onto the first surface, the first edge of the second surface intersects the first edge of the first surface, and - in the vicinity of a second overlap point where, in a projection onto the first surface, the second edge of the second surface intersects the second edge of the first surface. the first surface being laterally delimited by a first edge (b 11) and a second edge (b 21) which are rectilinear and not parallel to each other, in the part where it is superimposed on the second surface, the second surface also being laterally delimited, in the part where it is superimposed on the first surface, by a first edge (b 12) and a second edge (b 22) which are rectilinear and not parallel to each other and which, in a projection onto the first surface, intersect respectively the first edge (b 11) of the first surface and the second edge (b 21) of the first surface, characterised in that the device comprises an additional electrode (193; 213), integral with the first electrode (191; 211) and having an additional free surface which is substantially parallel to the second surface and which is partially superimposed on the second surface, the additional free surface being complementary to the first free surface, at least: - in the vicinity of a first overlap point where, in a projection onto the first surface, the first edge of the second surface intersects the first edge of the first surface, and - in the vicinity of a second overlap point where, in a projection onto the first surface, the second edge of the second surface intersects the second edge of the first surface. - in the vicinity of a first overlap point where, in a projection onto the first surface, the first edge of the second surface intersects the first edge of the first surface, and - in the vicinity of a second overlap point where, in a projection onto the first surface, the second edge of the second surface intersects the second edge of the first surface.