Figure 5: The variation of the ratio of the occupied areas in FESEM images for linear type coil, microsized coil, wave-like nanosized coil (w-NC), and knot-type nanosized coil (k-NC) as a function of the sample. The ratio of the occupied area by the linear-type and microsized coils was measured in the 1,000 magnified FESEM images and those by w-NC and k-NC in 5,000 high magnified FESEM images.