A Biocompatible, Magnetic‐Responsive Shape Memory Silicone Composite for Active Flow Controlling Valve

A magnetically responsive, biocompatible shape-memory silicone composite is developed for remotely actuated flow control. Incorporating PGD and NdFeB particles enables programmable, reversible shape changes triggered by magnetic field gradient force. The composite allows minimally invasive delivery and adaptive regulation of fluid flow in simulated vascular environments, demonstrating the potential for advanced biomedical valves in ocular or vascular applications.

Abstract

A magnetically responsive shape memory silicone composite is developed for fabricating an active valve in biomedical fluidic systems. The composite consists of magnetic neodymium–iron–boron (NdFeB) microparticles (MPs) and poly(glycerol-dodecanoate) (PGD) MPs in silicone. PGD has tunable transition temperatures (T_g ) of 42—50 °C, empowering shape programmability to the composite, while the NdFeB MPs make the composite responsive to a magnetic field gradient. The composite can be reprogrammed into a compact form for ease delivery and subsequently recovered to its original shape stimulated by external heat that is generated by an oscillation magnetic field (B_h ) applied to the NdFeB MPs. Because of the dramatically reduced stiffness above T_g , the valve shape can be actuated to a different one by exerted torques induced by a simultaneously applied actuation magnetic field (B_a ). By tuning the magnetic density and direction of B_a , the shape changing extent, e.g., bending angles, which determine the fluid flow resistance, can be modulated. This works provides a proof-of-concept for a programmable, remotely controlled valve for fluid regulation. The adaptability, biocompatibility, and capability for minimally invasive delivery highlight the potential of the valve for applications in drug delivery, embolization, and flow management in blood vessels and eyes.