A device for separating solids from a colloidal solution or suspension utilizing a permeable sheet comprised of passages or openings connecting the up and downstream faces of the sheet, an elastic support, a sealed enclosure separating the solids of the colloidal suspension from the clarified fluid filtered through the device, and a port or other means to allow transfer or collection of filtered fluid under the motivation of a simultaneously applied positive or negative pressure to the sheet. The sheet is affixed to the elastic support in a ballooned state at one or several discrete locations so as to allow transfer of fluid through the sheet while keeping solids outside the seal. The invention also pertains to a method of filtration using the above device to provide autogenous cleaning by alternating the elastic support from a slack and ballooned state during the course of filtration so as to discharge accumulated solids from the surface of the sheet.