FUEL CELL HUMIDIFIER

Example embodiments provide fuel cell humidifiers. An example humidifier comprises a stack of unit cells. Each of the unit cells may comprise a separator having a perimeter frame and first and second major faces, a first membrane sheet bonded to the perimeter frame on the first major face of the separator and a second membrane sheet bonded to the perimeter frame on the second major face of the separator. The perimeter frame and the first and second membrane sheets may define a cavity in an interior of the perimeter frame. Opposed frame ends of the perimeter frame may be apertured to allow a first flow to flow through the cavity in a first direction. The separator may include first and second ridges that extend across first and second frame ends. In the stack of unit cells the first and second ridges may space the unit cells apart from one another by contact with the separators of adjacent unit cells to provide passages extending through the stack of unit cells in a second direction transverse to the first direction. In some embodiments, the unit cells can all be stacked in the same orientation.