Certain aspects of the present disclosure provide a surgical cassette configured to engage a first plurality of rollers of a first roller head. The cassette comprises a face coupled to a first substrate, the face being at a first angle with respect to the first roller head's axis of rotation and a wall of first substrate being at a second angle with respect to the axis of rotation, wherein the first angle is different from the second angle. The cassette also comprises a first sheet positioned on the wall's surface, wherein the first sheet and the wall form first one or more pump segments configured to engage the first plurality of rollers in a position where force applied by each one of the first plurality of rollers on the first one or more pump segments has a direction that is not parallel to the first roller head's axis of rotation.