This report explains the process of fabricating a flexible chemical sensor on a Polyethylene terephthalate (PET) substrate by using screen-printing technology. The sensor was tested for its response to body fluid (saliva) using Electrochemical Impedance Spectroscopy (EIS). The experiments show that the sensor is capable of differentiating between water and saliva, and it can be used for identifying body fluids., i.e., distinguishing between saliva or water, and detecting personal biomarkers present in the physiology