Spider Silk Violin Strings with a Unique Packing Structure Generate a Soft and Profound Timbre

We overcome the difficulties in pulling long draglines from spiders, twist bundles of dragline filaments, and succeed in preparing violin strings. The twisting is found to change the cross section shapes of filaments from circular to polygonal and to optimize the packing structure with no openings among filaments providing mechanically strong and elastic strings. The spider string signal peaks of overtones for the violin are relatively large at high frequencies, generating a soft and profound timbre. Such a preferable timbre is considered to be due to the unique polygonal packing structure which provides valuable knowledge for developing new types of materials.

Figure 1

Photographs of spider strings. (a) About 3000 dragline filaments 90 cm in length collected from N. maculata spiders are aligned as a row. (b) Spider string prepared by furthermore twisting together three bundles prepared by twisting bundles with $\sim 3000$ dragline filaments.

Figure 2

Electron microphotographs of spider string. (a) Side view of the string. (b) Cross section of the dragline filaments from a N. maculata spider. (c) Cross section of the dragline filaments constituting the string after a large number of twists. Openings observed in the photo are due to the release of pressure when cutting. (d) Ratio of cross section shapes of dragline filaments constituting the string.

Figure 3

Power spectrum reflecting the tone magnitude obtained by a Fourier transformation of the sound-wave signals. The frequency of the fundamental tone was 293 Hz. (a) Spider string. (b) Steel string. (c) Gut string.