Micro-fluidic chambers for use in a liquid medicament delivery system, include a bottom substrate and a top cover, the top cover being spaced from the bottom substrate so as to define a height of the chamber, wherein, one or more walls or fillings are positioned in the chamber, the walls or fillings defining a fluid channel there between such that the fluid channel extends from an inlet conduit to an inlet of the chamber to an outlet conduit connected to an outlet of the chamber, wherein, each of the walls or fillings has a height less than the height of the chamber so as to define a fluid gap between a top surface of each wall or filling and the top cover; and wherein, the dimensions of the walls or fillings and the chamber are such that the fluid gap will be filled with liquid by capillary forces via the fluid channel when liquid is introduced into the fluid chamber.