The present invention relates to a slide having a first and a second major surface on opposite sides of the slide and one or more openings through the slide from the first major surface to the second major surface and one or more membranes mounted to one major surface of the slide over the one or more openings. The slide provides for both an ability to wash and to reduce the background fluorescence in the active membrane area. Preferably the membrane is made of nitrocellulose, nylon or PVDF. The opening(s) can be used to allow wash solutions to pass through the membrane and be removed along with the contaminants (unattached materials such as proteins or antibodies, dyes, salts, etc) from the slide thereby reducing the fluorescent background. Additionally, the one or more openings exhibit a lower fluorescence than a membrane that is laid over or attached to the slide, as neither the slide material or any adhesive is present which would otherwise increase the background fluorescence.