Inductive antenna stent: design, fabrication and characterization

This paper describes the design, fabrication, and electromechanical characteristics of inductive stents developed for intelligent stent applications. The stents, fabricated out of 316L stainless-steel tubes using laser machining, are patterned to have zigzag loops without bridge struts, and when expanded, become a helix-like structure. Highly conductive metals such as copper and gold are coated on the stents to improve their inductive/antenna function. The Q-factor of the stent is shown to increase by a factor of 7 at 150?MHz with copper coating. The expansion of the stent from 2 to 4?mm diameter results in a 3.2??increase in the inductance, obtaining ?1??H at a similar frequency. The stent passivated by Parylene-C film is used to characterize its resonance in different media including saline. The copper-coated inductive stent exhibits a 2.4??radial stiffness for 1?mm strain as well as a 16??bending compliance compared with a commercial stent, each of which is potentially beneficial in preventing/mitigating stent failures such as recoil as well as enabling easier navigation through intricate blood vessels. The mechanical stiffness may be tailored by adjusting stent-wire thickness while maintaining necessary coating thickness to achieve particular mechanical requirements and high inductive performance simultaneously.