An electronic device includes a substrate provided with a passing opening and a MEMS device including an active surface wherein a portion of the MEMS device is integrated sensitive to chemicalphysical variations of a fluid. Conductive elements such as metal-filled vias are formed in the host wafer and extend to its surface. The method utilizes a predetermined area relationship between the first area in the first field of view and at least one area in the second field of view to determine a second area in the second field of view.