Abstract: The invention provides a compact device and simple method for circulating fluid over the surface of a membrane. The device comprises a housing that in combination with the surface of the membrane defines an enclosed volume through which the fluid is circulated. Some embodiments will include a membrane holding layer, a fluid dispersing layer, or both. The membrane holding layer has an opening through it to expose a predetermined surface area of the membrane to the fluid. The dispersing layer has a set of openings, typically slits, through the dispersing layer to disperse fluid over the surface of the membrane. Some embodiments may include electrodes for sensing or applying electrical potential to the membrane. A particularly preferred embodiment comprises a double sided device including a first housing, dispersing layer and membrane holding layer on one side of a membrane and a second housing dispersing layer and membrane holding layer on the other side of the membrane.

Abstract: The invention provides a compact device of simple construction for holding a membrane in contact with a pair of fluids, one on each side of the membrane. According to the invention, the membrane holder comprises a base and an upper cap, with the membrane held between them. Fluids may be circulated over the surfaces of the membrane. Electrode ports are provided through which electrodes may be placed in proximity to the membrane for measuring or applying electrical potential across the membrane. The membrane holder comprises a base, which includes a lower plate and a center plate secured thereto, and an upper cap, which screws into the base by means of a threaded connection between them. The upper cap may be sealed to provide an enclosed volume for holding one of the fluids or the upper cap may be open to provide an open reservoir for holding the fluid. One or more membrane holders according to the invention may be placed in and held by a specially constructed heater stand.