Modeling of one-direction bendable articulated needle

Steerable needles are widely used in minimally invasive surgery. To perform medical tasks well in the deep of a human body, it is required that a needle is easier and more accurate to be controlled and steered. In this paper, the thrusting performances of a one-direction bendable needle are investigated in detail. Such a needle consists of a bevel-tip head, several articulations, and several sections. Articulations are designed that they can only be bent in the direction that is opposite to the bevel-tip, and they are more flexible than the other parts of the needle. The maximum bending angles of articulations are fixed. By changing the lengths of head and sections, and the maximum bending angles of articulations, the possible needle thrusting routes are analyzed. Also, the thrusting forces and moments are calculated based on the structure of the needle. The study results demonstrate that it is easier and more accurate to control and steer a one-direction bendable compared with previous needles. The developments of articulated needle provide the opportunities to design different articulated needle to suit different clinical cases.