A stent is described comprising a unit cell having a negative spring rate and a bistable function. The unit cell comprises first and second segments, the first segment being more rigid than the second segment. The second segment is coupled to the first segment, and the first segment comprises a substantially fixed sinusoidal shape. In the contracted state, the second segment is held stable in a sinusoidal shape, but when a force is applied the second segment bends out to a stable, convex-shaped deployed state. The second segments withstand the application of radial forces in the convex-shaped deployed state, and diametral recoil of the stent is minimized.