Research on blockchain in cyber-physical systems (CPS) focuses on enhancing security, reliability, and interoperability across interconnected physical and computational components. By integrating blockchain, CPS can achieve decentralized data management, immutable logging, and tamper-resistant communication, which are critical for applications in smart grids, autonomous vehicles, industrial automation, and healthcare systems. Smart contracts enable automated and trustworthy coordination between devices, while consensus mechanisms ensure data integrity and resilience against cyberattacks. Additionally, blockchain facilitates secure device authentication, access control, and privacy-preserving data sharing in CPS environments. Overall, incorporating blockchain strengthens the robustness, trustworthiness, and efficiency of cyber-physical systems.