Accurate detection of cortisol hormone is essential for diagnosing and managing stress-related disorders. Found in various bodily fluids like tears, blood, sweat, and interstitial fluid (ISF), ISF stands out for its stable pH, continuous extraction, and reduced sample contamination. Graphene-based sensors, owing to their exceptional electrical and mechanical properties, have garnered significant attention. This study introduces a novel approach utilizing a liquid-gate Graphene Field Effect Transistor (GFET) array device decorated with cortisol aptamer for precise ISF cortisol detection. Aptamers, chosen for their smaller size and ease of synthesis, serve as ideal recognition elements. Validation of Graphene functionalization was conducted via Raman spectroscopy and Atomic Force Microscopy (AFM). The proposed sensor exhibits a linear range of 1pM to 1uM, covering ISF's physiological cortisol range in high ionic background (1XPBS), with a sensitivity of 154 nA/dec. Leveraging liquid-gate GFETs adorned with aptamers holds promising prospects for advancing 2D sensors in personalized healthcare and wearable devices.