Research on the axis shape of an active catheter

Background An active catheter is a minimally invasive surgery catheter that can perform deflectable motions. The active catheter can be controlled from outside the body and moves like a snake, utilizing a multi-joint mechanism with distributed shape memory alloy (SMA) actuators. Methods It was considered that the deflection curve of the axis of the catheter is determined by the output force of the SMA actuators. Based on the large deflection theory, the deflection curve equation of the axis of the catheter was derived, using the precise form of the curvature. Results Through experimentation, the axial bending curve shape of the blended active catheter was measured precisely, and the experimental results were compared with the calculation results obtained from the large deflection theory and the circular arc hypothesis. The experimental results show that the curves calculated by large deflection theory are very close to the actual axis curves. Conclusions An active catheter prototype has been designed using the theory presented in this paper. Utilizing a vascular model, the active catheter-based invasive surgery was simulated. The experiment confirmed that the large deflection theory calculation method can be used to guide the design of the active catheter. Copyright (C) 2008 John Wiley & Sons, Ltd.