Fig. 4
Electric field simulations for the hydrogel collector (a-(i)) and a magnified image of the dashed rectangular in a-(i) (a-(ii)). (b) The dashed rectangular in a-(ii) showing the recessed region of the hydrogel collector. The electric field arrows along the reference line \(l(\mathrm{x})\) with the bending angles of 0° (b-(i)), 30° (b-(ii)), and 60° (b-(iii)). b-(iv) The angle of the electric field to the 3D ear cartilage-shaped hydrogel collector with the bending angle of 0°, 30°, and 60° along the reference line \(l(\mathrm{x})\)