Magnetic Catheter with Variable Stiffness and Self Sensing Using Electrically Conductive Polymer

Endovascular surgery has become a popular minimally invasive approach for vascular diseases diagnosis and therapy. However, the conventional procedure still has limitations. For one thing, most commercial guidewires/catheters are operated at the remote end, in which case the successful operation requires the surgeon’s high expertise and prudent operation. For another, most existing continuum devices have fixed properties, which cannot simultaneously satisfy the demand for navigating through a tortuous path and supporting the subsequent force application.<br/>This study proposes an adaptive catheter that can be magnetically steered and electrically softened, featured by improved manipulability and easy fabrication. An electrically conductive polymer (ECP) is first prepared by dispersing the carbon black (CB) filler into the polycaprolactone (PCL) matrix, which is further processed into small-scale U-shape electrode cores through 3D printing. Then, a magnetic catheter is fabricated by the molding process. The main components include the electrode core, the polydimethylsiloxane (PDMS) channel, the silicone jacket, and the tip magnet. The deformation can be controlled by external magnetic fields through applied torque, and the stiffness can be changed by powering electrical currents through joule heat-induced phase transition. Furthermore, based on the positive temperature coefficient effect of the ECP, the temperature-related stiffness can be estimated and maintained by monitoring and regulating the real-time current and voltage. This is helpful in dynamic environments, considering the temperature of the electrode core depends on both heat generation and dissipation.<br/>Various tests are conducted to calibrate the characteristics of the proposed ECP. Simulations are conducted to analyze temperature distribution to ensure body safety during heating. Magnetic catheter prototypes with single and multiple segments are fabricated for demonstration. The proposed catheter has the potential to improve operational safety and clinical outcomes of the interventional procedure.<br/>Acknowledgments<br/>The authors would like to thank the support from the Croucher Foundation Grant with Ref. No. CAS20403, and Multi-scale Medical Robotics Center (MRC), InnoHK at the Hong Kong Science Park.