Biomimetic Drag-reducing Design for Micro-robots in Vascular Locomotion

Micro-robots designed to travel through blood vessels show great promise for cardiovascular disease treatment, performing tasks such as delivering medicine directly to specific areas, removing blockages, and monitoring blood flow speed. However, turning this potential into reality in clinical environments remains highly challenging. These micro-robots must navigate within the complex, dynamic, and confined environment of the vascular system, where they face substantial blood flow resistance and constantly changing hemodynamic conditions that make it difficult to maintain effective propulsion and precise control. Moreover, blood is a non-Newtonian and multiphase fluid that exhibits shear-thinning behavior and pulsatile flow characteristics, resulting in time-dependent pressure gradients and fluctuating drag forces that further complicate motion control. In recent years, researchers have been increasingly adopting biomimetic strategies to optimize the structure, surface, and locomotion patterns of vascular micro-robots, drawing inspiration from natural organisms that efficiently move in viscous or turbulent fluids. These biomimetic approaches aim to reduce flow resistance, enhance propulsion efficiency, and improve adaptability to the harsh and variable microenvironment within blood vessels. The integration of intelligent materials, magnetically responsive actuation, and bioinspired surface engineering has further advanced the capability of micro-robots to operate under physiological flow conditions. This article offers a comprehensive overview of recent developments in this field, concentrating on the biomimetic drag-reducing design of vascular micro-robots. It specifically addresses three key aspects: biomimetic structural design, biomimetic surface design, and biomimetic motion patterns. While significant technical and biological hurdles remain, this review also looks ahead to future directions and clinical translation prospects, highlighting the transformative potential of vascular micro-robots for minimally invasive diagnosis and therapy in cardiovascular medicine.