PMC

Geometrical drawing method of the earwig fan. (A) Construction of the starting geometric elements (circle O, point A, and line MN) and projection of lines H_iF_i. (B) Construction of the radial folding lines and the ring-fold lines. (C) Modification system of the ring fold used to adjust the clearances between ring-fold lines in the folded shape, without interference to the flat foldability. (D) Idealized earwig venation drawn on a constructed crease pattern, showing the same characteristics as in the actual earwig wings (). (E and F) Schematic folding movements of the normal fan and the designed earwig fan, respectively.

Examples of models using the design software. (A) Extended circular model, resulting from extending the pattern around the rib base. This design can be used for deployable structures such as antenna reflectors and umbrellas. (B) Symmetrical circular model. (C) Deployable wing for microair vehicle, obtained by simplifying the earwig folding patterns. See Movie S5. (D) Interference control of the hinge parts by the provided designing software. (E) Three-dimensional printed earwig fan frame based on the model shown in D. All hinge parts can be stored compactly without interference.

Earwig hind wing in unfolded and folded shapes. Long and short ribs are in red and blue, respectively; bridge veins are in green. (A) Unfolded left hind wing of F.auricularia. (B) Detail of rib base. (C) Oval-shaped bending points (hinges). (D) Zigzagging of long and short ribs. (E) Folded left hind wing of F. auricularia as seen from above, corresponding to the shaded area in A. (F) Micro-CT image showing the conformation of veins inside a folded right hind wing of A. harmandi in underside view. (G) Diagram of F. (H) Same as F, in lateral view. Ap, apical stretch of long ribs; ba, basal stretch of long ribs.