A system and technique are enclosed for determining the effectiveness of a blood glucose therapy treatment. The valve includes a valve stem that contacts an upper surface of the flexible membrane so that if a substrate is attached to the lower surface of the flexible membrane when the first chamber is evacuated, the valve is actuated to generate a signal to the substrate detection system. Each passive air flow duct includes top and bottom openings for air flow. The two wiring groups sandwich a compound layer of an insulating film and a semiconductor film.