Abstract: This talk focuses on elucidating the complex dynamics and rheological properties of red blood cells (RBCs), which are fundamental to blood flow dynamics. RBCs possess remarkable deformability, enabling them to adapt their shape in response to shear forces, a critical ability for their passage through narrow capillaries and efficient oxygen delivery to tissues. Our investigation delves into studying these properties at the micro and nano scales, employing techniques such as Optical trapping and Atomic Force Microscopy to explore the rheology and behavior of RBCs. By carefully analyzing the force responses of RBCs under various regimes, we aim to understand the key factors influencing their behavior, notably membrane stiffness. Additionally, we will discuss methodologies for achieving controlled dynamics of Avian RBCs under the influence of external forces. The knowledge acquired from these studies holds substantial significance for many biomedical applications.