Fast-Response Variable-Stiffness Magnetic Catheters for Minimally Invasive Surgery

Area of Science:

• Medical Devices
• Materials Science
• Robotics

Background:

• Minimally invasive surgery requires dexterous tools like magnetically steered catheters.
• Current variable-stiffness catheters have slow transition times, increasing procedure duration.
• Faster stiffness changes are needed to improve surgical efficiency.

Purpose of the Study:

• To develop a fast-response, multisegmented catheter for minimally invasive surgery.
• To enhance the stiffness transition speed of variable-stiffness catheters using active cooling.
• To enable precise control and improved functionality during surgical procedures.

Main Methods:

• Fabrication of a multisegmented catheter using variable-stiffness thread (FRVST) with an integrated helical cooling channel.
• Utilizing a nontoxic shape memory polymer for the FRVST material.
• Implementing an active cooling system with water circulation to rapidly change the catheter's stiffness.
• Testing stiffness changes and transition enhancement compared to non-cooled versions.
• Evaluating catheter segment bending capabilities under an external magnetic field in air and water.

Main Results:

• The FRVST catheter demonstrated a 66-fold increase in stiffness change and a 26-fold enhancement in transition speed compared to the non-cooled version.
• Individual catheter segments achieved up to 127° bending in air and 76° in water under an 80 mT magnetic field.
• The integrated cooling channel effectively facilitated rapid stiffness modulation.

Conclusions:

• The developed fast-response variable-stiffness catheter significantly reduces transition times, addressing a key limitation in current technologies.
• The catheter's design allows for precise, selective bending and incorporates a functional inner channel for tool deployment and cooling.
• This innovation holds potential for improving dexterity, efficiency, and outcomes in minimally invasive surgical procedures like cardiac ablation.