Actuator subassembly (100; 201, 202, 203, 204) comprising: fit - a quadrangular frame (110; 130), preferably square-shaped, with four corner connectors (120, 120', 120", 120′′′; 320, 320', 320", 320′′′, 320 IV), - a movable element (160; 360), - a first shape memory alloy wire (130; 330, 331, 332, 333) contacting a first surface of said movable element (160; 360) and a second shape memory alloy wire (130'; 330', 331', 332', 333') contacting a second surface of said movable element (160; 360), said second surface being opposed to said first surface such that the two shape memory alloy wires are arranged in an antagonistic configuration in which they exert a force in opposite directions on the movable element (160; 360), characterized in that the movable element (160; 360) is placed in correspondence of the center of said quadrangular frame (110; 310) and connected thereto by elastically deformable arms (140, 140', 140", 140′′′; 340, 340'), and in that the first shape memory alloy wire (130; 330, 331, 332, 333) is fixed onto two of said corner connectors located at opposing positions, and the second shape memory alloy wire (130'; 330', 331', 332', 333') is fixed onto the other two opposing corner connectors, such that two wire planes, each containing a shape memory alloy wire with its relevant corner connectors, intersect at an angle of 90°±20°. - a quadrangular frame (110; 130), preferably square-shaped, with four corner connectors (120, 120', 120", 120′′′; 320, 320', 320", 320′′′, 320 IV), - a movable element (160; 360), - a first shape memory alloy wire (130; 330, 331, 332, 333) contacting a first surface of said movable element (160; 360) and a second shape memory alloy wire (130'; 330', 331', 332', 333') contacting a second surface of said movable element (160; 360), said second surface being opposed to said first surface such that the two shape memory alloy wires are arranged in an antagonistic configuration in which they exert a force in opposite directions on the movable element (160; 360), characterized in that the movable element (160; 360) is placed in correspondence of the center of said quadrangular frame (110; 310) and connected thereto by elastically deformable arms (140, 140', 140", 140′′′; 340, 340'), and in that the first shape memory alloy wire (130; 330, 331, 332, 333) is fixed onto two of said corner connectors located at opposing positions, and the second shape memory alloy wire (130'; 330', 331', 332', 333') is fixed onto the other two opposing corner connectors, such that two wire planes, each containing a shape memory alloy wire with its relevant corner connectors, intersect at an angle of 90°±20°. characterized in that the movable element (160; 360) is placed in correspondence of the center of said quadrangular frame (110; 310) and connected thereto by elastically deformable arms (140, 140', 140", 140′′′; 340, 340'), and in that the first shape memory alloy wire (130; 330, 331, 332, 333) is fixed onto two of said corner connectors located at opposing positions, and the second shape memory alloy wire (130'; 330', 331', 332', 333') is fixed onto the other two opposing corner connectors, such that two wire planes, each containing a shape memory alloy wire with its relevant corner connectors, intersect at an angle of 90°±20°.