A device can be used for both tissue expansion within a body of a patient as well as a permanently implanted prosthesis. Such a device can include an expandable elastomeric matrix and granules of a solute embedded within the matrix. The matrix can define boundaries of a plurality of chambers within the matrix. The device, when implanted within the body of the patient, can be exposed to fluid within the patient to create an osmotic gradient across a boundary of the device. Based on the gradient, fluid permeates the elastomer and gradually expands the chambers. The rate of expansion can be programmed to allow the body to naturally adapt to the volume, which increases until achieving a target volume in an expanded state.
