A variable stiffness manipulator with multifunctional channels for endoscopic submucosal dissection.

Abstract

Endoscopic submucosal dissection (ESD) has become the main treatment for early esophageal and gastric cancers, but the insufficient stiffness and large diameter of current devices increase the difficulty in operation. To address the above problems, this study proposes a variable stiffness manipulator with multifunctional channels for ESD. The proposed manipulator has a diameter of just 10mm and highly integrates a CCD camera, two optical fibers, two channels for instruments, and one channel for water and gas. Additionally, a compact wire-driven variable stiffness mechanism is also integrated. The drive system of the manipulator is designed, and the kinematics and workspace are analyzed. The variable stiffness and practical application performance of the robotic system are tested. The motion tests verify that the manipulator has sufficient workspace and motion accuracy. The variable stiffness tests show that the manipulator achieves 3.55 times of stiffness variation instantly. Further insertion tests and operation test demonstrates that the robotic system is safe and can satisfy the needs in motion, stiffness, channels, image, illumination, and injection. The manipulator proposed in this study highly integrates six functional channels and a variable stiffness mechanism in a 10mm diameter. After kinematic analysis and testing, the performance and application prospect of the manipulator are verified. The proposed manipulator can promote the stability and accuracy of ESD operation.