Biointegrated Micro/Nano-Robots: Design, Applications, and Future

Biointegrated micro/nano-robots (BI-MNRs) integrate living biological units with engineered modules to enable adaptive functions beyond conventional micro/nano-robots. Their actuation and navigation can be precisely guided by externally applied energy fields that interact with either biological entities or responsive synthetic materials, and these interactions support programmable motion and task execution in complex microenvironments. BI-MNRs have shown strong potential in targeted therapy, minimally invasive intervention, medical imaging, and environmental remediation. In contrast, conventional micro/nano-robots remain constrained by strong dependence on external apparatus, limited biocompatibility, and reduced controllability under physiological disturbances such as shear flow, immune surveillance, and heterogeneous microstructures. Biointegration contributes to overcoming these challenges by combining intrinsic cellular motility and sensing with artificial components that enable controllable actuation and functional integration. This review summarizes locomotion principles in microscopic environments and discusses representative control strategies based on magnetic, light, acoustic, chemical, and electrical stimuli. Design and fabrication architectures across bacterial, algal, germ cell, and somatic cell-based platforms are compared. Recent advances in targeted delivery, multimodal imaging, biofilm eradication, biosensing, and pollutant removal are reviewed. Key challenges in control robustness, fabrication reproducibility, stability and shelf-life, systemic safety, and ethical governance are discussed. Future directions include swarm-level coordination, scenario-driven design, and environmentally compatible operation.