Shape morphing of sub-electrodes by stylet and cannula tuning

Owing to the pre-curved shape and the bevel tip of the stylet (the detailed structure of stylet and cannula depicted in Figure 6), the shape of sub-electrode can be tuned on demand by adjusting the relative axial position of expanded stylet and cannula. As illustrated in Figure 7A, the expanding of a sub-electrode can be categorized into three morphing states that are featured by the length of stylet remained in the cannula (it has to be noticed that the expanded length of stylet is designed to be no less than that of cannula): 
State 1, the stylet is expanding with the cannula. In this state, the expanded length of stylet equals to that of cannula. The cannula is somehow deflected by the pre-curved stylet and thus create a slightly deflected angle of the sub-electrode. (As illustrated in Figure 7A, the expanded length of cannula is the only variable in this morphing state.)  
State 2, the stylet is expanded out of the cannula and the expanded part of cannula is occupied by the pre-curved part of stylet. In this state, the pre-curved part of stylet is not fully expanded so that the straight part of stylet do not enter into the cannula. For a certain expanded length of cannula, the deflected angle keeps almost unchanged in this state and a circle can be used to fit the profile of the pre-curved part of stylet.\cite{Gerboni2017,Adebar2016} ( As illustrated in Figure 7A, the expanded length of cannula and stylet are both tunable in this morphing state. )  
State 3, the stylet is expanded out of the cannula and the straight part of stylet exists in the cannula. Ideally, Ideally, the straight part of the stylet will not deflect the cannula. For a certain expanded length of cannula, the deflected angle in this state is subsequently smaller than that in state 1 and 2. ( As illustrated in Figure 7A, the expanded length of cannula and stylet are both tunable in this morphing state. )