A device and method allowing evaluation of the contents of a sealed primary container by means of an integral sensor which is separated from the contents of the sealed primary container yet provides information on quality of the contents of the primary container without breaking the sealed system. The integral sensor device includes a biosensor retained within a plastic construct by a gated-pore membrane. Pores in the membrane open in response to an environmental change in the primary container allowing the contents of the primary container to contact the biosensor. Status of the contents of the primary container can be determined by inspection of the biosensor, visually or via a fiberoptic probe, through the optical window of the plastic construct.