In this paper, we propose a new simple device for this purpose by using a membrane in which a specific enzyme is immobilized. The membrane produces fluorescence after combining with a specific metabolite. The membrane, on which the tissue is mounted, is deposited on a quartz substrate that is used as a light guide for the excitation UV light. Metabolite release is observed by a CCD camera from the opposite side of the substrate. The paper also describes the reduction of background fluorescence by means of image processing technique. We increased the number of UV light to two so that the background noise can be eliminated. Finally the release of ATP from specific layers in rat cerebellum was successfully observed. In the future, it is to be believed that instead of manual tuning, we might produce a program which using auto tuning for a more precise image processing.