Basic concepts for active implantable valve development

Based on fundamental considerations concerning implantable valve actuating mechanisms and a review of recent low-energy actuators, we propose four concepts to adjust or switch an implantable valve. The Bellow-Concept makes use of a standard actuator and hermetic encapsulation with flexible bellows, where force can be transmitted by deflection of the bellows. The Shape-Memory-Alloy-Concept considers a biocompatible Shape-Memory-Alloy (SMA) actuator, which can be directly immersed in body liquids. The Stepper-Motor-Concept makes use of a hermetically encapsulated rotatory actuator, with the rotatory action being transmitted magnetically through the rigid encapsulation wall. Finally, the Magnetic-Spring-Concept proposes a hermetically encapsulated linear actuator and linear magnetic force transmission through the rigid encapsulation wall. We found the Magnetic-Spring-Concept the smallest and most simple one.