A A S
12 Scientific American, February 2019 Illustration by Brown Bird Design
BIOMIMICRY
Crustacean
Camera
e device mimics mantis
shrimp’s astounding vision
anti rim hold the title or the
astest punch in the animal kingdom—
po er ul enough to break seashells and
a uarium glass. hey also boast some
o the orld’s most complex, extra-
ordinary eyes. Human eyes have three
kinds o light receptor cells, but these
shrimp have a dozen, allo ing them
to sense properties o light invisible to
other animals.
ngineers at the niversity o llinois
at rbana-Champaign have no made
a camera that closely copies the crusta-
cean’s impressive visual system. he
device, described last October in Optica,
is a one-inch cube, and researchers say
it could be made in bulk or apiece.
hey believe it could ultimately be used
to help cars detect hazards, to let mili-
îDßālß ̧³xääxxD ̧øDxl ̧ßäDl- o ed targets, and to enable surgeons to per orm more accurately. antis shrimp have t o visual superpo ers. For one, they can sense “polarized light, in hich all the aves un du late in the same plane (unpolarized light vibrates in every direction . ight U ̧ø³³ ̧ ̧U¥xîäD§ÿDāä ̧³îD³äD
polarized component, and this property
̧
§îD³ßxþxD§ ̧U¥xîäîDî ̧îxßÿäx
blend into the background mantis
äßÇøäxîî ̧³lÇßxā³îxßU§øx
tinged ocean environs. hey can also
detect an extensive span o light intensi-
ties kno n as dynamic range, hich
lets them see very bright and dark areas
at once.
he ne camera emulates both abili-
ties. lectrical and computer engineer
iktor ruev and his colleagues made an
array o tiny, silicon-based light detectors
similar to those ound in commercial polar-
ization cameras. But hereas conventional
detectors produce an electric current that
increases linearly ith light intensity, the
ne detectors respond exponentially.
his yields a dynamic range about ,
times higher than today’s commercial
cameras. he researchers also covered the
detectors ith microscopic aluminum
ires to imitate microvilli, the tubular
äîßø`îøßxä³äßÇxāxäîDî§îxßD³l
sense polarized light.
For a real- orld test, the team drove
around in a car mounted ith their ne
camera and a standard one. Pictures
rom the shrimp-eye camera had much
higher contrast, especially in oggy and
rainy conditions and in scenes ith a lot
o light and shado s, ruev says. he mantis shrimp is the only creature
that can sense a ull spectrum o colors
and polarization, says homas Cronin,
a pro essor o biological sciences at
the niversity o aryland, Baltimore
County, ho as not involved in the study.
his characteristic makes it ideal or a
camera to emulate, he says “You ould
xî`§xDßDxä ̧
̧U¥x`îä³D` ̧ǧ
`DîxlUD`¦ß ̧ø³lîDîDßxl`ø§îî ̧
pick out ith other techni ues.
— Prachi Patel A
Sunlight contains waves that vibrate in every
direction. Polarized light waves vibrate in just
one. The human eye perceives polarized light
Då ̈DàyjD ́ùåD ́`yày®¹ÿymUĂ ̈ïyàåÎ A S S
Each “pixel” in a mantis shrimp’s compound
eye has a rodlike structure (rhabdom) made
of light receptors with threadlike structures
(microvilli) that are alternately stacked at right
angles. Cells in the two hemispheres of the
eye are tilted at 45° to each other. So the eyes
́yy`ï`¹ÿyà¹ùàȹ ̈DàĆDï¹ ́mày`ï¹ ́åÎ S A A
The new pixel sensor is an array of silicon-
based detectors covered with aluminum
́D ́¹Āàyå¹åyïUĂpï¹y®ù ̈Dïyïy
ȹ ̈DàĆDï¹ ́ ̈ïyà ́®`à¹ÿ ̈ ̈ ́åà®ÈyĂyåÎ
Each silicon detector exponentially converts
light to electric current, enabling the camera
to sense a large range of light intensities.Dorsal
hemisphereMultidirectional
light wavesUnidirectional
0¹ ̈DàĆ ́ ̈ïyà light wavesCompound eyeMicrovilli RhabdomsVentral
hemisphere 0°0° 45°135° 90°90°45°135°288 pixels
384 pixelsPixel
NanowirePolarization
imagerHow the Camera Mimics the Shrimp EyeSOURCE: “BIOINSPIRED POLARIZATION IMAGER WITH HIGH DYNAMIC RANGE,”BY MISSAEL GARCIA ET AL., INOPTICA,VOL. 5, NO. 10; OCTOBER 20, 2018© 2019 Scientific American