The shape morphing of sub-electrode and its interaction with tissue phantoms. (A) Shape morphing principle of sub-electrode. Several possible shapes are illustrated in each morphing state. The enhanced images of a sub-electrode in the (B) air and in the (C) phantom, marked with deflected angles and bending radii. (D) The comparison of the shape parameters of sub-electrode in the air and in the phantom. (E) The change of deflected angle in different morphing states. (F) The change of bending radius with the increment of expanding speed.