Systems and methods for providing torque to an assistive device are disclosed. In an embodiment, an apparatus comprises a material arranged to define a volume of space. The material may comprise a flexible portion and having a first surface and a second surface. The material may have a first position, in which the material is bent along the flexible portion and the first surface contacts the second surface. When the material is in the first position, an increase in pressure to the space creates a force between the first surface and the second surface. The material transitions from the first position to a second position in response to the force between the first surface and the second surface. The apparatus may be attached to an assistive device or other machine, such as an orthosis or prosthesis, in order to provide a torque.
