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

the availability of spicule-inspired, robust optical fibres would certainly be of interest for
integration into common daylight guidance systems.
Façade elements
A structural element containing spicule like glass fibres could be installed in façades of
non-residential buildings for adaptable lighting. The fibres should span from the outside of
the façade to the interior allowing for the passage of light. On the interior face of the
building they would protrude from the solid matrix they are contained in which allows to
bend them. The interior face of this element would be covered a perforated layer of dye
solar cells. In the default state, spicules are straight, providing lighting for the interior
through the orifices of the perforated solar cell. Under excess sunlight conditions, or when
desired, the spicules can be bent to provide light for the solar cells.
This bending could be governed by an external controlling mechanism or triggered by the
incidence of solar light in an autonomous response mechanism. As a tentative mechanism to
induce bending it is suggested to intercalate expandable elements between the free ends of
the fibres. Thus, when excess light irradiates onto the façade, the elements would be
expanded, leading to a diversion of sunlight onto the organic solar cells.
Sponge spicules of some demosponges possess lens-shaped extremities pointing towards
the exterior (Figure 20e). These were found to be effective at coupling more light into the
spicule (Müller et al., 2010). Thus following the pathway of spiculogenesis closely, it should
be possible to achieve similar structures to increase the amount of light coupled into the
building.
Specifically dye solar cells are suggested here, because they are increasingly cheap to
produce but in most cases degrade quickly due to UV radiation, temperature changes and
other environmental factors (Ke et al., 2010) (Yoo et al., 2011). These could clearly be
minimized inside buildings, for temperature changes are minimal inside buildings and the
transmission spectrum for all investigated sponge spicules cut off the entire UV spectrum; a
characteristic that should be easily retained in biomimetic fibres.
Following the natural example of symbiotic sponges, the building would thus provide
protection for these elements and yet let light of the needed wavelength pass for energy
conversion (and here: lighting) in the interior. These panels could therefore provide glare-
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