Abstract
BACKGROUND: Robotic end-effectors are being developed to facilitate image-guided minimally invasive needle-based procedures, such as tumour ablation, biopsy, thoracentesis and blood sampling. METHODS: A novel mechanical end-effector was designed to address the challenges associated with any major needle-based procedure, focusing on liver biopsy and ablation. In this end-effector embodiment, the distal end of a single articulating arm can grip needles and instruments and allows a fairly high number of degrees of freedom of movement during the complex motions associated with positioning and driving needles, as well as the periodic motions associated with breathing patterns. Tightening a cable that runs through the articulations fixes the arm in a rigid state, allowing insertion of the gripped needle. RESULTS: A design is presented that will require electro-mechanical stimulation and remote joystick control. The associated forces of cranial-caudal motion of soft tissue organs affects design constraints. A simulation study defined the process with tissue phantoms with mechanical properties in the range of hepatic tissue and the overlying abdominal wall. The robotic arm coupled with our end-effector could be deployed in an image-guided interventional suite. CONCLUSIONS: Such a switch-able and flexible mode for a robotic arm could overcome much of the current limitations for automated needle placements for mobile targets, and could mitigate risks from breathing or patient motion with a rigid needle gripper in place.