In the current design, the structure parameters of the initial capacitive sensor and micro-probe are shown in Fig. 3. The dimension of the floating plate, as well as the dimension of springs is designed based on stiffness difference between floating plate and springs. When a probing force is applied to the probing sphere, the probing force causes a tilt or translational motion of the floating plate while the springs experience elastic deformations, so stiffness difference is to keep floating plate rigid enough and springs elastic, besides MEMS process is also an important factor to determine the dimension. The structure parameters of the initial capacitive sensor and micro-probe are shown in Fig. 3 and Table 1.