MASTER THESIS Biomimetic potential of sponge ... - IAP/TU Wien

excel in flexibility due to their gradient in Young’s modulus and hardness while these
properties are homogeneous in communications fibres, making them brittle (Aizenberg et
al., 2004). In commercial fibres failure is due to simple crack growth (Sundar et al., 2003).
Spicules are also known for their high purity that compares to quartz grade glass (Wang et
al., 2011a).
Figure 19 Sponge spicules resemble commercial optical waveguides. Apart from being made of the same
material, sponge spicules can have a similar diameter like glass fibres, the most commonly used waveguides for
telecommunications. Most interestingly they have a similarly graded refractive index - a high-index core and a
lower index cladding ((b), (e), (h) and (k)) (Aizenberg et al., 2004). Depending on the refractive index of the
surrounding medium (n ext ), spicules can act as a multimode waveguides (like (c) and (f)) for n ext < n spicule, or as
single-mode waveguides (like (i)), if n ext > n spicule . Another important prerequisite for the spicule to operate as a
multimode fibre is that the difference in n between the environment and the material of the spicule be
considerably larger than the difference between core and cladding (Voznesenskiy et al., 2011) © by
fiberoptics4sale.com for (a)-(i) and (Aizenberg et al., 2004) for (j) and (k)
The macroscopic scale of sponge spicules is a good precondition for the successful
transfer of concepts from nature to technology. As Mayer (2005) pointed out, the
adaptation of general architectural configurations and material characteristics has its limits.
Very often insurmountable difficulties occur when trying to translate a natural process at the
nano- or microscale to a technologically feasible structure at the macroscale; and that at a
reasonable cost. Our understanding of the deep principles at the basis of properties of
biomaterials is usually incomplete, which is an obstacle especially when scaling effects set in.
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