Abstract: The present disclosure relates to an apparatus and methods for applying a force on a sample. In particular, the present disclosure relates to a stress cell (200) comprising a frame (205); an actuator arrangement (210) coupled to the frame; and a coupler (220) for coupling the actuator arrangement to the sample (230). The coupler (220) includes a first coupler portion connected to the actuator arrangement (210) and a second coupler portion connectable to the sample (230). The first coupler portion is flexibly coupled to the frame. The actuator arrangement (210) comprises a first element (214) having a first variable length and a second element (212) having a second variable length, and is adapted to vary a difference between the first length and the second length to provide the force.