The issue of scalability remains an important future area
of research. When increasing the scale of designs it is widely
known that the changes in dimensionality will greatly affect
performance, however, it remains to be seen how performance
will change in the presence of other significant factors such as
turbine wake interactions in the case of arrays. One potential
solution is to simply use larger 3-D printing and wind-tunnel
capabilities whereby larger designs could be produced by the
same method. On the opposite end of the spectrum, microwind
turbines that are 2 mm in diameter or smaller can be
used to generate power, such as for wireless sensors [79],
and in this case more precise 3-D printers would be required.
Moreover, wind turbines can find useful applications on any
scale, e.g., a recent feasibility study [80] for powering wireless
sensors on cable-stayed bridges examined turbines with a
rotor diameter of 138 mm in wind conditions with an average
of 4.4 m/s (similar to the artificial wind conditions used in this
paper)