Design of RFA device

Design and implementation of the individually-controlled sub-electrodes and their stylets and cannulas is illustrated in Figure 3B. Sub-electrodes can be withdrawn/expanded inside the outer shaft of electrode, and the head of electrode is designed to be a cone for better tissue insertion. The outer shaft is covered with an insulating polymer sheath for the electric insulation. To avoid cross-infection, invasive parts of surgical tools are often designed as single use. However, as the control and driven module are essential parts in our electrode design, to balance cost and minimize cross-infection simultaneously, our proposed RFA device consists of a disposable handle box where electrode is integrated and a reusable control box (photos in Figure 4), which are both modularized components for convenient assembly and re-assembly. In the handle box, each of the stylets and cannulas is fixed to a sider and they only have one degree of freedom, Figure 2C-D. Steel wires wound on the winders connect to the slider for tendon-driven control of these stylets and cannulas. The winders are the interface of handle box that connect to the control box. Six servos in the control box actuate their winders accordingly via an array of couplings. These servos are pre-programmed to follow real-time instructions for various motions. In addition, our device is designed to be compatible with a commercial RF generator and the detailed operation method is elaborated in Experimental section/methods and Figure 5.