Abstract: One embodiment of the present invention provides a piston assembly having a piston housing filled with an electrolyte; a housing within the piston housing that divides the piston housing into a first portion and a second portion, the housing having apertures, a shaft connecting the housing to a piston head outside of the piston housing; and a porous material inside of the housing in contact with the electrolyte. Additionally, there are provided a method for filling the delivery chamber with a delivery fluid by withdrawing the piston head from within the delivery chamber. Yet another embodiment provides a method for filling a fluid delivery assembly by withdrawing a shaft from within the fluid delivery assembly to simultaneously displace a moving pump element within the delivery chamber and bypass fluid around a housing in the pump chamber.

Abstract: The present invention provides a fluid delivery system having a first chamber, a second chamber and a third chamber; a flow-through pump element separating the first chamber from the second chamber; a moveable pump element separating the second chamber from the third chamber; a first outlet in communication with the third chamber; and second outlet in communication with the second chamber. Additionally, the present invention provides methods of operating a fluid delivery system having a first chamber, a second chamber and a delivery chamber by reducing the volume of the second chamber while increasing the volume of the delivery chamber without operation of a flow-through pump element that separates the second chamber from the first chamber.