A Variable Stiffness Magnetic Catheter Made of a Conductive Phase‐Change Polymer for Minimally Invasive Surgery. (6th February 2022)

• Record Type: Journal Article
• Authors: Piskarev, Yegor; Shintake, Jun; Chautems, Christophe; Lussi, Jonas; Boehler, Quentin; Nelson, Bradley J.; Floreano, Dario
• Is Part Of: Advanced functional materials. Volume 32:Number 20(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-02-06
• Subjects: conductive shape memory polymers -- continuum robots -- magnetic navigation -- medical robotics -- multifunctionality -- soft robotics -- variable stiffness; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.202107662
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract: Variable stiffness (VS) is an important feature that significantly enhances the dexterity of magnetic catheters used in minimally invasive surgeries. Existing magnetic catheters with VS consist of sensors, heaters, and tubular structures filled with low melting point alloys, which have a large stiffness change ratio but are toxic to humans. In this paper, a VS magnetic catheter is described for minimally invasive surgery; the catheter is based on a novel variable stiffness thread (VST), which is made of a conductive shape memory polymer (CSMP). The CSMP is nontoxic and simultaneously serves as a heater, a temperature sensor, and a VS substrate. The VST is made through a new scalable fabrication process, which consists of a dipping technique that enables the fabrication of threads with the desired electrical resistance and thickness (with a step size of 70 µm). Selective bending of a multisegmented VST catheter with a diameter of 2.0 mm under an external magnetic field of 20 mT is demonstrated. Compared to existing proof‐of‐concept VS catheters for cardiac ablation, each integrated VST segment has the lowest wall thickness of 0.75 mm and an outer diameter of 2.0 mm. The segment bends up to 51° and exhibits a stiffness change factor of 21. Abstract : A variable stiffness (VS) catheter made of a conductive shape memory polymer (CSMP) is developed. The CSMP used here is a nontoxic material that simultaneously serves as a heater and a temperature sensor while providing VS. The catheter, fabricated through a scalable process, exhibits a stiffness change factor of 21 and bends up to 51° under an external magnetic field.