Provided herein is a cell encapsulation device comprising an internal chamber suitable for holding biological agents, wherein the internal chamber is disposed between a first semipermeable layer and a second semi-permeable layer, and the first and second semi-permeable layers are mounted on a supporting frame surrounding a perimeter of the internal chamber; wherein the supporting frame comprises a first frame element and a second frame element, and the first and second frame elements co-operate to position the first and second semipermeable layers at a predetermined separation distance between the layers.