Biointerfaces have emerged as an exciting and rapidly expanding field. The highly versatile biointerfaces and tunable platforms have improved our understanding of biological problems and developed better therapeutic approaches for diseases. By designing functional materials-cell biointerfaces and utilizing fabrication techniques and physics, existing tools for cell stimulation have been extended to study cellular responses to external factors, including electrical signals, forces, and biochemical signals. In recent years, there has been remarkable growth in the field, allowing for a deeper understanding of biological complexity and more rigorous development of methods. This thesis focuses on electrochemical cell modulation, bioelectrically augmented exosome production, and molecular and magnetically triggered T-cell signaling by employing carbon-based devices, interdigitated gold electrodes, and inorganic heterostructures, respectively.