Session B7
#249
Disclaimer—This paper partially fulfills a writing requirement for first year (freshman) engineering students at the
University of Pittsburgh Swanson School of Engineering. This paper is a student, not a professional, paper. This paper is
based on publicly available information and may not provide complete analyses of all relevant data. If this paper is used for
any purpose other than these authors’ partial fulfillment of a writing requirement for first year (freshman) engineering
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THE EFFECTIVENESS OF DIELECTRIC ELASTOMER ACTUATORS IN
SOFT ROBOTICS
Meyer Jeffers, [email protected], 3:00-5:00 Mena Lora, Bianca Coulter, [email protected], 5:00-7:00pm Sanchez
Abstract- Soft actuators are becoming more prevalent in the
world of soft robotics. Due to a wide array of soft processors,
this paper will focus on a complete analysis of Dielectric
Elastomer Actuators (DEAs). It goes through the history of
the technology, noting notable advancements. Studying the
mechanical background of DEAs is important to
understanding how the current research is performed. DEAs
work through an elastomer and compliant electrodes to
achieve a large level of deformation. The possibilities that
this amount of deformation allow have led to increasing
research towards applications of DEAs. The application of
DEAs in prosthetics and soft robotics is the primary area of
research.
Key Words—Actuator, Biomimetics, Dielectric,
Elastomer, Soft Robotics.
WHY A SOFT ACTUATOR?
Throughout the span of mankind there has always been
a need to create facsimiles of human parts to stand in for
missing real ones. Initially we could make due with gold
spheres placed into the eye socket, or wooden pegs where a
leg should be. However, as science and engineering
progressed, so too have these prosthetics. Now we are
capable of semi-robotic limbs that can sense the movements
of muscle and react accordingly, or artificial hearts capable of
pumping blood without ever hearing a beat. Unfortunately,
these technologies still have drawbacks and we haven’t been
able to perfect them working from the ground up. Instead of
working from the ground up it may be possible to instead
work with the organic references around us. Dielectric
Elastomer Actuators, hereafter referred to as DEAs, are
cheap, easy to manufacture actuators that work in incredibly
similar ways to muscles. Using these actuators, we can create
models of nearly every kind of muscle, and use it to both help
replace and understand the human body. Because of this,
DEAs are an ideal candidate for use by mechanical engineers,
especially in the biomechanical engineering spectrum.
MECHANICS
University of Pittsburgh Swanson School of Engineering 1
03.03.2017
Actuators are the parts of machines that are responsible
for creating movement. They do this by converting some type
of input energy into mechanical energy. The input is
sometimes hydraulic, pneumatic, sometimes even chemical.
DEAs stand out as an actuator due to their greater levels of
deformation. Their movement isn’t bound do a single axis,
which means unlike other actuators they have infinite degrees
of freedom. DEAs are composed of ElectroActive Polymers
(EAPs) sandwiched between compliant electrodes that
maintain conductivity throughout the use of the actuator. The
polymers are usually polyurethane, acrylic, or silicon based
due to their elastic properties. When an electric charge is
applied, the electrodes become oppositely charged and
compress the membrane, reducing the thickness and
increasing its area [1].
The reason DEAs compress and expand is due to a force
called Maxwell stress. The effective compressive stress can
be calculated by multiplying the absolute and relative
permittivity of the EAP with the quantity of the voltage
divided by the thickness of the actuated membrane squared.
In equation form that looks like this:
p = ℇ 0 ℇ r(V/h)2
Where p is the effective compressive stress, ℇ 0 is the initial
permittivity and ℇ r is the absolute. V is the voltage being
passed through and h is the thickness of the membrane. The
equation to predict the DEAs strain, for strains under 20%,
has also been calculated. The strain is approximately equal to
the negative effective compressive stress divided by the
elastic modulus relating to the strain. In equation form:
sz = -p/Y
Where sz is the strain and Y is the elastic modulus. For high
strain, it is estimated as negative 1 plus e to the power of the
negative quantity of the amount of electrical energy
converted to mechanical energy divided by the effective
compressive stress. In equation form:
sz = -1 + e-(wcp)
Meyer Jeffers
Bianca Coulter
Where wc is the amount of electrical energy converted into
mechanical energy. Looking at the equations you can see that
the stress is proportional to the dielectric constant of the EAP
and inversely proportional to the thickness of it. Because of
this, as the electric field increases, the thickness of the
membrane decreases and can form a feedback loop causing
the DEAs to become unstable and breakdown. These very
basic and early equations in DEAs helped propel research
into DEAs and set the foundation for future research. These
are just a small sample of the equations discovered that
govern the mechanics of their actuation [1].
Using these equations engineers and researchers design
configurations of EAP that will become DEAs. To create
linear motion folded, helical, and stack actuators have been
developed, and show promise in the realm of biomimetics.
Folded DEAs are a single layer of EAP that is folded over
itself to increase its height. It compresses under charge,
which makes it remarkably similar to human muscle [2].
Stacked DEAs are EAPs stacked on top of each other with
the compliant electrodes compressing similarly to folded
DEAs, but use many layers of EAP as the name implies. This
means it’s easier to check for quality in each layer and
remaking a single broken segment rather needing to replace
the entire actuator at once. However, the ideal stacked
actuator will be more expensive than an ideal folded actuator.
Helical DEAs are made of a hollow EAP tube with two
helical compliant electrodes. When a charge is applied it
contracts in length and widens, so as to be similar to a spring.
Some DEAs work by elongating rather than compressing,
dissimilar to muscle. There are also single layer DEAs, where
one long polymer is layered with electrodes, and when a
charge is applied the DEAs lengthens and pushes against its
surroundings. There are also circular DEAs that surround an
object longitudinally, and compress the object when a charge
is applied. These are just some of the configurations of DEAs
that give it the versatility to be used in many situations.
there yet, the DEAs may become useful for astronauts who
need a new limb, or so on. On a smaller more immediate
level, the stability of DEAs in response to temperature allows
it to minimize its effect on the internal environment of a
human if it is implemented as an artificial muscle intertwined
with other organic parts of the body [1].
DEAs also show an incredible ability for future
improvement. Due to the materials that compose DEAs, they
have the ability to build in improvements. One such
improvement is they can become self-healing and increase
their longevity by releasing chemicals that fill in and
regenerate pieces of the EAP of electrode that are damaged
over time [3]. They also have the ability to come with sensors
built into the DEAs. This removes the separation of sensor
and what needs to be sensed and allows DEAs to collect and
react to more accurate information, with less distance to
signal across [4].
The speed of DEAs in comparison to other soft
actuators is also invaluable. While vacuum actuators require
time to siphon gasses in and out of its chambers and shape
memory alloys must be heated and cooled overtime, DEAs
respond relatively quickly and can oscillate movement very
easily. This is what allows DEAs to be used for locomotion in
annelid, jellyfish, fish, even quadruped models already, and
may one day soon be applied to bipedal motion in models of
the human leg.
DEAs are also very small and can be linked in
smaller chains to create gradual lower powered movement
over a longer surface. This is what allows researchers to use
stacked or folded DEAs or use the long single layer DEAs
depending on its use. Annelid-like robots frequently mimic
the segmented body parts of their inspiration and have
segmented parts that work in tandem to locomote the robot.
DEAs are also remarkably cheap. A common acrylic polymer
used in many DEAs is VHB 4910 by 3M. If you buy 1 ¼’’ by
36 yards case of it, it costs $41 per roll [5]. A popular carbon
conductive grease used as an electrode in conjunction with
VHB 4910 is offered by M.G. Chemicals. One 80g tube of
carbon conductive grease 846 is $18 [6]. A garage scientist
could easily afford these materials and the others to make
their own soft robots. Each material is advertised for other
uses and is in no danger of stopping its mass production,
which makes material availability for DEAs incredibly high
and costs remarkable low.
BENEFITS OF DEAS
There are many reasons DEAs are more beneficial in
biomimetics than other actuators. The most immediately
obvious reason is the infinite degrees of motion DEAs are
usually capable of. Contrasting that with say a pneumatic
actuator, that is only able to push and pull in one direction,
there is a clearly more adaptable option [1].
Another benefit of using DEAs rather than hard
actuators, is that rather than solid rigid parts composing the
device, it can be soft and flexible. This softness allows DEAs
to be used in very close proximity to humans and survive
bumps and scrapes from unknown environments. Even
compared to other soft actuators DEAs are superior [1].
Their actuation isn’t reliant on pressure or heat and
is thus unaffected by the presence of unexpected temperature
changes or environments. This makes DEAs and stable
candidate for actuation in space, or in high altitude, or even
the crushing pressures of the ocean. While humans aren’t
DISADVANTAGES OF DEAS
With their plethora of advantages, there are bound to be
some disadvantages. The three largest concerns are the
longevity, the responsiveness, and amount of deformation the
DEAs are capable of [1].
DEAs are inherently soft, and while that is
advantageous in versatility, that does make it vulnerable to
sharp objects. The softness is also an issue when it is used for
gripping. The actuator gives way easily to the pressure of the
object and requires more power to grip, and in doing so
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compliance, compactness (low volume/power ratio, <10 -8 m3
MPa), high force density (skeletal muscles can generate
stresses from 0.1 to 0.5MPa), fast response time (mechanical
tension of skeletal muscles becomes maximum 30 ms after
neural excitation for a single twitch) and high efficiency of
energy conversion (biological muscles show values as high as
45-70%).” By using the best electroactive polymers they
found available, silicone elastomers with 30 weight percent
titanium oxide, they constructed helical and folded elastomers
to create a contracting effect rather than expanding. This
allows the elastomers to be used more like muscles. The
contraction of these actuators (see Fig 1 allows for use in and
android robotic face, or a simulation of the actuation of an
anthropomorphic skeletal upper limb [10].
A year later, Sungkyunkwan University published a
paper titled “Artificial Annelid Robot Driven by Soft
Actuators.” As of then, locomotion similar to that of annelids
had been desirable, but true biomimicry had not been
possibly with technology at the time. Previous attempts
utilized Shape Memory Alloys, but were inefficient and slow
due to the movement being controlled by heating and cooling.
DEAs were decided to be more successful in the creation of
the model. Because of DEAs’ ability to act similar to muscle,
Sungkyunkwan University was able to take the two main
muscle groups in earthworms to model the actuators after.
causes the EAP to become thinner and thus more fragile and
easily broken under the kind of pressure gripping something
requires.
DEAs are also not as fast as many hard actuators,
and response speed is something people have tried to
increase. To do this, they often pre-strain the actuator before
there is any charge. While this works to increase response
speed, it decreases the lifespan of the actuator.
Finally, DEAs aren’t as strong as we need in every
situation. A single DEA is not as strong as a single
component of another actuator. While this can be taken care
of with stacked or folded DEAs, it becomes a problem in
smaller scales. While it can sometimes hold up to 60 times its
weight, the fact is that it usually doesn’t happen and other
actuators are more efficient, such as pneumatic actuators,
capable of holding up thousands of pounds in a
comparatively light weight device [7][8].
HISTORY OF DEAS FOR USE IN SOFT
ROBOTICS
DEAs began as a developing technology in the early
1990s, and was implemented into the even more recent field
of soft robotics in the early 2000s. Using the properties of
previously studied actuators, a research team sponsored by
the Korean Ministry of Science and Technology spoke at a
conference detailing the possible use of DEAs in annelid-like
robotics. Named ANTagonistically-driven Linear Actuator
(ANTLA), it utilized the same technology that we have been
calling DEAs. At this point in time DEAs were such a
fledgling technology that the original proposed actuator only
used experimentally competent equations, rather than the
theoretical ones in use today. The technology was so early on
that it’s more valuable to point you to the article rather than
give the equations listed in it. In summary, the experimentally
derived equations allowed them to build a model actuator that
exhibited muscle-like characteristics [9].
Half a decade later Pisa University spoke in a
conference on how to use DEAs in a biomimetics. In
layman’s terms, they proposed using DEAs as artificial
muscles. Similar to how annelid-like robots used DEAs to
simulate the full range of movement in the muscles of worms,
the Interdepartmental Research Centre at Pisa proposed using
DEAs to simulate the complexities and unique properties of
organic muscle. As quoted from the conference, “muscles are
neither pure force generators (like DC motors) nor pure
motion generators (like stepper motors); rather, they behave
like springs, with tunable elastic parameters” The ability to
have shifting parameters is key to the success of muscles,
sacrificing excess precision unnecessary for natural
environments for versatility and strength. For that purpose, it
is much more valuable to mimic the parameters muscles can
achieve than to create an actuator for prosthetics in an
isolated conception. Specifically, “linear contractions,
robustness, stability, long lifetime, built in tunable
Figure 1 Stack (a), Helical (b), and Folded (c)
DEAs [10]
The actuators used in this experiment were unique in that
they did not pre-strain the film. The model used spin coated
silicon elastomer film, coated with carbon electrodes and
stacked to create layers until each larger section had a total
thickness of 0.75 mm. Each film was placed into a circular
frame with a slightly smaller radius than the film in order to
increase control over the expansion of the film. Then each
disk was put into segments containing twelve disks placed in
a hexagonal pattern, 6 on each side. Each segment was
attached to another by the DEAs with silicon adhesives on
each side. When finished the earthworm robot was covered
by an artificial skin and tested. The robot, when finished,
weighed less than 5 grams, and moved at 6% of its body
length per sec at 10 Hz. Compared to a medium sized
earthworm travelling around 0.2% of its body length per
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second, they created an artificial earthworm that was just
waiting to be built upon [11].
CURRENT USE OF DEAS IN SOFT
ROBOTICS AND PROSTHETICS
ETHICS
Current use of DEAs is moving to a more
biomechanical spotlight. The ability DEAs possess to convert
electrical energy to mechanical energy is useful for
biomimetic muscle models, and possibly prosthetics. The
sheer mechanical force DEAs are capable of attract many
researchers and engineers to consider their use in both small
scale and large scale productions. A few of the recent
advancements include bioreactors mimicking the natural
movement of their environment, adaptive lenses similar to
natural eyes, and even soft bodied locomotion that mimics
natural muscle [1].
One way that DEAs find use is in biomechanical
simulations. Where many people assume cells communicate
and react only to chemical signals, it’s important to realize
that there are many mechanical signals and processes that we
have yet to accurately study. To simulate the mechanics of
the human biome, specifically that of the small intestine, the
journal Bioinspiration & Biomimetics published an article on
a prototype bioreactor that simulates the peristalsis inside the
small intestine. Using a popular acrylic based co-polymer
(VHB 4910 by 3M), between carbon grease electrodes (846,
M.G. Chemicals) pre-stretched to 300%. The disk actuator
was fitted with the bioreactor, a flexible chamber that can be
compressed at one end. The compression, in periodic waves
and intensities, mimics the radial contractions of the intestine
[12].
Going from the lower abdomen to the head, another
successful model of nature, using DEAs, is an electrically
tunable soft solid lens based off the optical accommodation
birds and reptiles are capable of. Birds and reptiles often
experience varying environments, including environments
where a single lens’s depth of field is affected, such as
underwater, or to maintain focus at a depth. In these places,
birds and reptiles have adapted ways to compensate for that,
most notably by manipulating the shape the of the lens.
Previous attempts at modelling the lenses using different
types of actuators, including a liquid lens DEAs based
actuator, but the low tolerance to environmental changes
make the DEAs a far better candidate. The solid lens model
utilizes a curved lens over a clear polymer (VHB 4910 by
3M) with opaque electrodes (Carbon Conductive Grease 846
M.G.) preventing light from entering through any point not
the lens. The solid lens is secured to the polymer on a flat
face, while the hemispherical portion of the lens points
outwards. The lens is used to manipulate the light passing
through it by changing the radial curvature of the lens
through contraction of the DEAs. This can allow light from
different fields of depth to hit the same place behind the lens,
similarly to how eyes concentrate light. When compared to
the liquid lens DEAs based model, the solid lens “halves the
required driving voltages, simplifies the process, and allows
for more versatility in design.” The adaptive tunable lens can
DEAs are a simple technology. They have a single
purpose and cannot do anything outside that purpose. They
are cheap and the materials are available to anyone, they are
not designed to bring anyone harm, they cannot force a user
to use them. The pose similar danger to other actuators except
for the fact that DEAs are soft and even less likely to hurt
someone. Assessing the ethics of using DEAs is like
assessing the ethics of an axle in your car. The axle on its
own cannot do anything and is only considered for ethical
dilemma in its use. DEAs in their individual uses may have
ethical concerns. In prosthetics it may have ethical concerns
depending on the sale and use, but that doesn’t speak on
DEAs as a whole.
SUSTAINABILITY
The sustainability of DEAs is tricky to talk about.
Currently there are concerns towards the manufacturing of
acrylic acids and acrylic based polymers. The types of DEAs
made with acrylics work well enough that the EAP used the
most is acrylic based. However, once acrylic is manufactured
it is easily recycled and can be used again to make more
EAP. Even that could be a null issue, because EAPs are not
exclusively acrylic based. Any natural rubber can
theoretically become an EAP, and sprinkling metals onto the
rubber can increase its electroactive capabilities [1]. Other
materials are available for use in DEAs as shown in Fig. 2.
The different materials allow for increasing number of
options to use when finding the most sustainable material to
make DEAs out of. These options are where DEAs gain their
strength in sustainability.
Figure 2 Actuation strain versus pressure/density
for different actuators [1]
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Bianca Coulter
be used in many technologies that require adaptive vision,
such as auto-focus in cameras, phones, and tablets, and
optical microscopes or machine vision [13].
Instead of focusing on one part of the body, it can
still be useful to build an entire artificial organism.
Sometimes it’s useful to analyze another organism in order to
better understand how we work, and in the IEEE 2016
conference on Intelligent Robots and Systems (IROS)
J.Shintake, H. Shea and D. Floreano discussed 2 underwater
robots. The fish was designed with a silicon elastomer (CF192186, NuSil Technology). The mechanics of the fish are
remarkably similar to human muscles, with a DEAs acting as
the muscle on either side. While one DEA has a voltage
applied, the other doesn’t. The charged DEA pushes against
the body of the fish while the other gives way to the
movement, providing a small amount of thrust behind the
fish. As the charge is released the other DEA has a voltage
applied to it and the process begins again. While not perfectly
mimicking the muscles in fish tails, it is a huge step forward
in accurate muscle technology [14].
pre-stretch with decent movement and similar range of
motion to a human.
Another possible future application of this
technology is in retinal surgery. This won’t be happening
with humans for a very long time, but if we understand how
the irises of land mammals and reptiles and flightless birds
adjust to changes in light, we could attach a sensor to the
eyebrow or nose of an animal with damaged irises or retinas,
and attempt to attach an artificial iris. While the resolution is
currently subpar, the lens is capable of focusing enough to
promote survival. Further tests can then be done to compare
the function of the artificial eyes to the eyes of organic
animals [13].
CONCLUSION
DEAs are viable, even ideal, options for future research.
The mechanics of them are well known and can be used to
find new configurations of EAPs and electrodes to continue
using DEAs in innovative ways. The benefits and
disadvantages are clear, and the benefits still outweigh the
advantages in many situations. Their use has been
advantageous in both the past and the present and currently
holds great potential for the future. DEAs are a growing
technology that will see more and more use in the growing
fields of biomimetics, prosthetics, and maybe even in other
technologies that require actuation.
FUTURE USES OF DEAS
To preface this section, this is not as heavily focused
on the research done on DEAs, but is mostly the authors’
educated opinions on theoretically possible technologies that
rely on DEAs. Because the capabilities of this type of
actuator are still being researched and advanced, it is not at a
stage where it makes sense for major research to be done on
future applications. However, researchers who create these
actuators often have specific applications in mind when
developing their technology, and will often make comments
on how their specific experiment is useful in regards to that
application.
Using the same technology that created the annelid
or the fish, the next step is to combine them in a series of
small segmented limbs [11][13]. Using both types of DEAs,
the annelid’s compression based motion and the fish’s
extending based motion, the human body could be roughly
modeled. By having antagonistically activated fish-like DEAs
assist the motion of primary annelid-like DEAs to push and
pull joints a rudimentary model of the human body could be
formed. For instance, if you decide to model the human
forearm with an attached hand, the skeletal structure doesn’t
need much change. Connecting the actuators to the tendon
points in the human musculoskeletal system is also not in
need of change. The difference between the natural muscle
and DEAs system is that instead of antagonistic muscle
opposing the motion, you have an antagonistic annelid-like
DEAs opposing the motion of the primary annelid-like DEAs
and a secondary fish-like DEAs assisting the primary annelidlike DEAs with an antagonistic fish-like DEAs next to the
primary annelid-like DEAs. With only modifying the bones
of the wrist and the push and pull mechanisms of the muscles,
you could create a model of the human arm with minimal
SOURCES
[1] G. Gu, J. Zhu, X. Zhu “A Survey on Dielectric Elastomer
Actuators for Soft Robots” Bioinspirations & Biomimetics 23
Jan.
2017
Accessed
22
Feb.
2014
http://iopscience.iop.org/article/10.1088/17483190/12/1/011003
[2] F. Carpi “Folded Contracile Dielectric Elastomer
Actuator” SMART Group Youtube Channel 16 Jan. 2013
Accessed
1
March
2017
http://aip.scitation.org/doi/full/10.1063/1.4869294
[3] S. Hunty, T. McKay, I. Anderson “A SelfHealingrDielectric Elastomer Actuator” Applied Physics
Letters 17 March 2014 Accessed 3 March 2017
http://aip.scitation.org/doi/full/10.1063/1.4869294
[4] K. Jung K. Kim, H. Choi “A Self-Sensing Dielectric
Elastomer Actuator” Sensors and Actuators A: Physical 16
May
2008
Accessed
10
Jan
2017
http://www.sciencedirect.com/science/article/pii/S092442470
700814X
[5] Uline “3M 4910 VHB Acrylic Tape” Uline Catalogue
Accessed
2
March
2017
https://www.uline.com/BL_6038/3M-4910-VHB-AcrylicTape
[6] Newegg “MG Chemicals 846-80G Carbon Conductive
Grease” Newegg Catalogue Accessed 2 March 2017
https://www.newegg.com/Product/Product.aspx?Item=9SIAC
044WE5401&ignorebbr=1&nm_mc=KNC-GoogleMKP-
5
Meyer Jeffers
Bianca Coulter
PC&cm_mmc=KNC-GoogleMKP-PC-_-pla-_-HI++Test+%26+Measurement+Tools-_9SIAC044WE5401&gclid=Cj0KEQiAot_FBRCqt8jVsoDKo
ZABEiQAqFL76LLgaAhzsPGhFjxVRsWI6oLvBLRe3ze_eT
7t7cA49rwaArfR8P8HAQ&gclsrc=aw.ds
[7] J. Shintake, S. Rosset, B. Schubert, S. Mintchev, D.
Floreano, H. Shea. “DEA for Soft Robotics: 1-gram Actuator
Picks up a 60-gram Egg” Electroactive Polymer Actuators
and Devices. 1 April 2015 Accessed 10 January 2017
http://proceedings.spiedigitallibrary.org/proceeding.aspx?arti
cleid=2239754
[8] S. Campbell “Guidelines for Selecting Pneumatic
Cylinders” Machine Design 29 Sept. 2011 Accessed 2 March
2017
http://machinedesign.com/pneumatics/guidelinesselecting-pneumatic-cylinders
[9] H. Choi, A. Ryew, K. Jung, H. Kim, J. Jeon, J. Nam, R.
Maeda, K. Tanie. “Soft Actuator for Robotic Applications
Based on Dielectric Elastomer: Dynamic Analysis and
Applications” Robotics and Automation, 2002. Preceedings
ICRA ’02. IEEE International Conference. 11-15 May 2002
Accessed
22
Feb.
2017
http://ieeexplore.ieee.org/document/1013722/
[10] F. Carpi, D. De Rossi “Biomimetic Dielectric Elastomer
Actuators” Feb. 2006 Accessed 22 Feb. 2017
http://ieeexplore.ieee.org/abstract/document/1639234/
[11] K. Jung, J. Koo, J. Nam, Y. Lee, H. Choi “Artificial
Annelid Robot Driven by Soft Actuators” Bioinspirations &
Biomimetics. 5 June 2007 Accessed 9 January 2017
http://iopscience.iop.org/article/10.1088/17483182/2/2/S05/meta
[12] D. Cei, J. Costa, G. Gori, G. Frediani, C. Domenici, F.
Carpi, A. Ahluawalia “A Bioreactor With An ElectroResponsive Elastomeric Membrane For Mimicking Intestinal
Peristalsis” Bioinspiration & Biomimetics 5 Dec. 2016
Accessed
24
Feb.
2017
http://iopscience.iop.org/article/10.1088/17483190/12/1/016001/meta
[13] M. Pieroni, C. Lagomarsini, D. De Rossi, F. Carpi
“Electrically Tunable Soft Solid Lens Inspired by Reptile and
Bird Accomodation” Bioinspiration & Biomimetics 26 Oct.
2016 Accessed 26 Feb. 2017 http://iopscience.iop.org/17483190/11/6/065003
[14] J. Shintake, H. Shea, D. Floreano “Biomimetic
Underwater Robots Based on Dielectric Elastomer Actuators”
IEEE/RSJ International Conference on Intelligent Robots and
Systems (IROS) 19-14 Oct. 2016 Accessed 2 March 2017
http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=775972
8&tag=1
ACKNOWLEDGMENTS
I would like to thank the hardworking graders that allow
this conference and paper to happen.
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