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294 Biomimetics: Biologically Inspired Technologies

(a) (b)
6
0.25

y = −0.4859x + 7.9069 0.20
Numerical Aperture (NA)
5 R = 0.9797
2
Ln(f ) 0.15

4 0.10

0.05

3 0.00
5 6 7 8 9 0 2000 4000 6000
(c) Ln(P ) (d) Fluidic Pressure (Pascals)
Figure 11.3 (a) Two centimeter aperture fluidic adaptive lens; (b) a picture of resolution measurements of fluidic
adaptive lenses using positive standard; (c) dependence of focal length on fluidic pressure in a spherical
fluidic adaptive lens. The solid line is a line fit of the data, indicating that the focal length is approximately
proportional to the inverse square root of the pressure. (d) Numerical aperture versus fluidic pressure in spherical
fluidic adaptive lens. (From Zhang, D., Lien, V., Berdichevsky, Y., Choi, J., and Lo, Y. Applied Physics Letters 2003:
82(19), 3171–3172. With permission.)

fabricating a unique array where individual photodetectors are connected by flexible structures on
top of a PDMS polymer substrate. These S-flexures are a key requirement in the development of an
artificial cephalopod eye, as each pixel remains connected to those around it while allowing a
flexible, curve retina (Figure 11.5).
While research is ongoing, it is apparent that the development of this type of optical system will
allow for a much wider field of view (180 to 2008) than conventional cameras. At the same time, the
device will maintain a compact arrangement, allowing for space-efficient implementation in
various applications.

11.2.3 A Foveated Imaging System

A final example of a camera-type system borrows more from the strategy of certain living organisms
than from the design. A commonly observed trait in animals is the ability to scan a scene in order to
increase their field of view. Many animals, including humans, have a much higher resolution in the