An apparatus for biomimetic expression of breast milk can comprise a breast interface having an expandable membrane configured to mimic the geometry of an infant's mouth. Various regions of the expandable membrane may be configured to simulate the structure and/or function of various parts of an infant's mouth. The expandable membrane may comprise one or more of a distal sealing region configured to simulate the lips, a superior region configured to simulate the hard palate, an inferior protruding region configured to simulate the gums, an intermediate curved region configured to simulate the tongue, and one or more internal expansion regions configured to simulate the soft palate and the throat. The expandable membrane may have a varying thickness throughout the one or more various regions to enable movement of the regions similar to the movement of the corresponding regions of an infant's mouth during nursing.
