סמינר מחלקתי Yonatan Horovitz

School of Mechanical Engineering Seminar
Wednesday, April 15, 2015 at 15:00
Wolfson Building of Mechanical Engineering, Room 206

Active Catheter Driven by a Thermo-Hydraulic Actuation

Yonatan Horovitz

MSc Student of Dr. Gabor Kosa

Catheters and flexible endoscopes are usually steered by mechanical wires that are driven from the base of these tools. Due to friction and buckling there is a need to place the driving actuator of the catheter at the catheter's tip. Such active catheter's maneuverability is much higher than the wire-driven devices. A problem with active catheters is the difficulty to create high enough bending torques or bending forces using micro-actuators placed at the catheter's tip.

In this study, a novel actuation method is presented to overcome this problem. The bending torque is created using internal pressure in a sealed tube, and the bending direction is controlled by varying stiffness in the tube’s cross-section.

In order to create the varying stiffness, two mechanisms were investigated. The first mechanism is based on electrostatic actuation, where parallel plate actuators were used to increase the tube’s stiffness at specific regions. The second mechanism is based on thermal actuation, using resistance wires embedded in the tube’s wall to locally soften the tube.

Both methods were modeled and optimized theoretically. Actuator prototypes were designed and tested. The electrostatic actuator did not achieve significant bending results. On the other hand, with the thermal actuator we were able to show the feasibility of the actuation method. We found that a 4 mm OD actuator made of TPU can bend up to ±12° although the heating of the tube was significant, at about 100°C.