Abstract: An implantable artificial sphincter system provides long-term adjustment via transcutaneous energy transfer (TET), minimizing invasive adjustment through adding or removing fluid via a syringe. An infuser device provides bi-directional fluid transfer via a flexible conduit to a sphincter band, such as a gastric band, by a combination of thermodynamic actuation and a piezo-electrically disengaged drum brake assembly that thereby achieves a desirable small volume device. A propellant within a propellant cavity surrounds a metal bellows accumulator biased at body temperature to either expand or collapse the bellows accumulator with the opposite direction of movement effected by a thermal element that heats in combination with a negatively-biased propellant or cools in combination with a positively-biased propellant.

Abstract: A remotely controlled gastric band system that is practically immune to external magnetic fields, such as from a Magnetic Resonance Imaging (MRI) machine, incorporates a bi-directional pump and fluid reservoir to adjust fluid volume for hydraulic control of a gastric band. A piezoelectric driver (e.g., rotary actuator, linear actuator) selectively compresses and expands a metal bellows hermetically sealed within a biocompatible and nonferromagnetic enclosure or case such as titanium. Directly sensing a position of the metal bellows yields an accurate reading of volume contained therein, allowing for closed-loop control of the gastric band.