idic switch, which are the core parts of
an optofluidic solar lighting system. As
shown in Figure 1, sunlight is concentrated and coupled into the fibers by the
optofluidic solar concentrator panel installed on the roof of the building and
adaptable to the position of the sun.
The infrared portion of light is separated and directed into the infrared photovoltaic solar cell, while the ultraviolet
portion is extracted and can be used instead of the UV lamp for air purification
during the daytime. Finally, the residual
visible part of the sunlight is directed into
each room for interior illumination.
The light flow is dynamically controlled
by the tunable optofluidic switch, and the
excess visible light can be further used
to generate electricity via photovoltaic
solar cells.
In a comparison between two different
solar energy systems for indoor lighting –
photovoltaic and solar indoor lighting –
Psaltis and colleagues estimate that the
peak energy density of sunlight on the
Earth’s surface is about 1000 W/m2 at
noon. At this power, the team calculates
that 1 m2 of solar cell can generate just
200 W of electrical power to fluorescent
lamps. On the other hand, for an indoor
solar lighting system, the luminous power
from a 1-m2 area of sunlight collector
generates 3000 W of electrical power to
fluorescent lamps at the same optical flux
output. Therefore, directly transporting
the sunlight for indoor lighting can be
an excellent way to conserve energy and
could be much more effective than photovoltaic technology.
Although optofluidics involves precise
control over fluids and optics at the small
scale, it must be scaled up for successful
application to energy problems – a chal-
lenge that has yet to be addressed.
