Biodegradable Microrobots for Active Navigation and Delivery on Ex Vivo Cardiac Models

Magnetically driven microrobots are emerging as valuable tools for biomedical applications due to their high precision, remote controllability, and fuel-free operation. However, the development of simple, biocompatible, and biodegradable microrobots that can effectively navigate and function on physiologically relevant biological surfaces remains a significant challenge. In this study, we present biocompatible spherical microrobots driven by magnetic fields, capable of performing multiple tasks over the complex surface of chicken heart tissue. The microrobots are designed by synthesizing biocompatible spherical PLGA (Poly (lactic-co-glycolic acid)) microparticles and coating them with iron, a magnetic material, on one side via the physical vapor deposition technique. Under a rotating magnetic field, the microrobots exhibit active rolling motion, with their movement precisely controlled through both manual open-loop and automated closed-loop settings. We then tested the efficiency of the microrobots on the complex and rough surface of ex vivo chicken heart tissue, where they showed consistent rolling motion and trajectory tracking across heterogeneous tissue surfaces. Additionally, the microrobots demonstrated the ability to transport cells to targeted locations on the tissue surface. Furthermore, biodegradability studies confirmed that the microrobots degrade over time, with no significant cytotoxicity observed at selected timepoints. This simple design, combined with biocompatibility, versatile locomotion, and biodegradability, positions these microrobots as promising candidates for active therapeutic delivery, in vivo diagnostics, and a wide range of biomedical applications.