We are developing a quantitative electronic biosensor displaying a protein recognition thanks to the covalent grafting of an antibody. The detection device lies on interdigitated array microelectrodes (IDAM), covered with alumina (Al2O3) to protect the underlying aluminum and enhance the electrical coupling, hence known for its high signal-to-noise ratio, its fast detection and its simple testing procedure. As the dimensions of the IDAM can determine the sensitivity of the sensor, we processed 4 structures with varying electrode widths and spacings in the same silicon chip and assessed their individual performance. The sensing area of each senor is 200*200 µm2 and the overall chip-size is 3*3 mm2. The sensor is mounted in DIL-16-package, then partially encapsulated by resin. The resin formed 2 mm high wall. Influenza A viruses cause annual epidemics and occasional pandemics that spread worldwide. The nucleoprotein A is essential for the survival of this virus and is thus well-conserved. We grafted an anti-nucleoprotein A antibody at the surface of the IDAM using a layer-by-layer technique. To assess the reliability of the procedure, the presence of the antibody was checked by confocal microscopy. A uniform grafting was assessed at 61 % on each sensor. To assess the feasibility of the detection, different dilutions of a model analyte (goat anti-mouse) conjugated with a 40 nm-gold bead was added and capacitive/conductance vs frequency measurements were carried out on each sensor. The best sensor was composed of 2 µm-wide electrodes with an interspacing of 2 µm. A detection was realized over a logarithmic range of 4.5x106 down to 45 gold particles. The correlation with the nucleoprotein A in a clinical sample will be the next step. So, we setup a preliminary biosensor for the quantification of a protein using a capacitive measurement that can achieve a detection of 45 gold beads linked to an antibody.