Methods and apparatus for transferring pressure during expression of human breast milk

A device for expression and collection of breast milk, the device includes an actuatable assembly and a breast interface. The breast interface is sized to receive a breast and form a fluid tight seal against the breast. The breast interface includes an expandable membrane disposed within at least a portion of the breast interface. The expandable membrane reversibly deforms in response to actuation of the actuatable assembly, thereby applying vacuum pressure at the breast to express the breast milk. The expandable membrane comprises a plurality of expandable pleats which extend radially outward from a central longitudinal axis of the breast interface.