Researchers at Johns Hopkins University have developed a pair of magnetic 'millirobots' designed to navigate the human body and deliver medication directly to heart tissue. These robots, which are roughly the size of a pencil tip or a grain of rice, aim to treat life-threatening heart infections, such as endocarditis. Currently, treating these infections often requires weeks of intravenous antibiotics, which can be diluted before reaching the heart, or high-risk open-heart surgery. The millirobots offer a minimally invasive alternative, potentially reducing treatment times from weeks to a single day or less.
The system utilizes a two-part robotic mechanism to ensure precise delivery. One robot, the 'needle module,' is designed to latch onto the specific site of infection on the heart tissue to serve as a docking station. A second robot, the 'drug module,' carries the medication to this station, where it magnetically docks and slowly releases the antibiotics. Both robots are guided wirelessly by an external electromagnetic coil system, similar in principle to an MRI machine. Because the robots are powered by these external magnetic fields, they do not require internal batteries or motors, allowing them to remain small enough to navigate tight spaces within the body.
The team successfully tested the millirobots on phantom heart models and real porcine heart tissue, where the robots moved autonomously even against simulated blood flow. While the current research focuses on cardiac infections, the developers suggest the technology could be adapted to treat other hard-to-reach diseases, such as cancer. Future testing will involve more complex phantom hearts that simulate muscle contractions and the rhythmic beating of a human heart to further refine the robots' navigation and docking capabilities.
One notable limitation of the current study is that it has been tested primarily on phantom models and porcine tissue; the transition to human clinical use will require navigating the complexities of human vascular systems and varying heart geometries. Additionally, while the robots can be replaced to allow for repeat doses, the long-term stability of the needle module's docking mechanism in a dynamic, beating environment remains a key area for future investigation. The researchers have published their findings in the journal *Advanced Materials Technologies*.