In the present study, we have developed a capacitance electrochemical biosensor based on silicon nitride substrate (Si3N4/SiO2/SiP/Al) for Tumour Necrosis Factor Alpha (TNF-α) cytokines detection. Micro-contact printing, Fluorescence microscopy characterization and contact angle measurement (CAM) were carried out during the bio-functionalization of the biosensor surface. Mott-Schottky analyses were applied for TNF-α detection within the range of 1 pg/mL to 30 pg/mL in which the immunosensor has exhibited a good linearity, a sensitivity of 4 mV.pM−1 and 4.4 mV.pM−1 in PBS and artificial saliva (AS) respectively. While the LOD was found at 0.38 pg/mL and 1 pg/mL in PBS and AS respectively. The developed immunosensor has also demonstrated a high and good selectivity for TNF-α detection in human AS when compared to other interferences like Cortisol and Interleukin-10. The performances of the developed biosensor are very promising for biomedical application to predict the first sign of inflammation. Schematic illustrations of the chemical surface modification and bio-functionalization process of the immunosensor with antibodies Anti-TNF-α. Display omitted •Fabrication of a capacitance electrochemical immunosensor based on silicon nitride transducer (Si3N4/SiO2/SiP/Al).•Silicon nitride surface was activated and chemically modified with TESUD to immobilize antibodies Anti-TNF-α.•µCP, Fluorescence microscopy and CAM measurement were carried out during the bio-functionalization of the biosensor surface.•Biosensor has exhibited a high sensitivity and a good selectivity for TNF-α cytokines when compared to IL-10 and Cortisol.•Interesting LOD of TNF-α cytokines was found at 0.38 pg/mL in PBS and 1pg/mL-1 in AS.