ELECTROACTIVE POLYMER, IONIC POLYMER,ARTIFICIAL MUSCLE

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Electroactive Polymers
(EAP)
Presented by
Girish Raghunathan (1459409)

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What is Electroactive Polymer ?
Electroactive polymers, or EAPs, are polymers that exhibit
a change in size or shape when stimulated by an electric
field.
A typical characteristic property of an EAP is that they will
undergo a large amount of deformation while sustaining
large forces.

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STRESS VS STRAIN FOR POLYMERS
Fig. 1(a) and (b)stress strain
relation for polymers

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Fig 2. Comparison of strain of EAP with other
technologies

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It is a thin film polymer technology that can do 3 things:
1) Act as a sensor – Take the film and stretch it, and it tells
how much stress had been applied to
the film.
Fig. 3 EAP film before stretching Fig. 4 EAP film after stretching

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2) Act as an actuator – When electric field is applied to the
film, it will change shape and this
shape change is used to move various
fluidic products such as in a pump
or valve application.
Fig. 5
Fig. 6 Fig. 7

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3) Generated Voltage – It is used as an energy harvester.
As the film is stretched, and then
allowed to relax, it will generate a
voltage which is stored in a battery
or a capacitor.
Fig. 8

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HISTORY
Emerged in 1880 while Wilhelm Rontgen was experimenting on
natural rubber.
M.P. Sacerdote followed up on Roentgen's experiment by
formulating a theory on strain response to an applied electric field in
1899.
The first piezoelectric polymer called Electret was discovered in
1925.
In 1969, it was found out that Polyvinylidene Fluoride (PVDF)
exhibits a large piezoelectric effect.
In early 1990’s, ionic polymer-metal composites was found and it
exhibited electroactive properties far superior to previous EAPs.
First Electroactive Polymer Artificial muscles were developed in
Japan in the year 2002.
In 2008, Industrial production of EAP’s for artificial muscles began.

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TYPES OF EAP:
There are two types of EAP’s:
1) Dielectric - Materials in which actuation is caused by
electrostatic forces between two electrodes which squeezes
the polymer. They are capable of very high strains. It
changes it’s capacitance when an electric field is applied.
Fig 9: Working principle of dielectric elastomer actuators

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2) Ionic – Ionomeric polymer-metal composite is an EAP
that bends in response to an electrical activation as a
result of mobility of cations in the polymer network or
negative ions on interconnected clusters. Electrostatic
forces and mobile cation are responsible for the bending.
Fig 10 : Ionic EAP

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Fig. 11 Polarization in an ionic EAP

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MECHANISM:
 The EAP basic architecture is made up of a film of an
elastomer dielectric material that is coated on both sides with
another expandable film of a conducting electrode.
 When voltage is applied to the two electrodes a Maxwell
pressure is created upon the dielectric layer. The elastic
dielectric polymer acts as an incompressible fluid which means
that as the electrode pressure causes the dielectric film to
become thinner, it expands in the planar directions. Electrical
force is converted to mechanical actuation and motion.

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Fig. 12 Behaviour of EAP

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EAP as a sensor
It consists of a laminated polymer with conductive inks that
changes capacitance when it is deformed, stretched or
contracted. The unique properties of EAP sensors are highly
attractive wherever deformation is to be measured.
Fig. 13 EAP before deformation Fig. 14 EAP after deformation

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EAP as an actuator
It is particularly light, robust, energy conserving, and can make
some exceedingly fast movements which cannot be done by
conventional solenoids. The density of these materials are
comparatively lower by a factor of 8. Valve movements can be
made x3 faster by these polymers.
Fig. 15 EAP before applying electric field Fig. 16 EAP after applying electric field

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Once a field is applied, the cations gather to the side of the
polymer in contact with the anode causing the polymer to
bend.
Fig. 17 Ionic EAP before
applying electric field
Fig. 18 Ionic EAP after
applying electric field
Fig. 19 Ionic EAP when the
applied electric field is
reversed

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Advantages Disadvantages
 Can operate in room
condition for a long time.
 Requires HV on the order of 150
MV/m (Ferroelectric 20 MV/m).
 Rapid response (m sec level)  Compromise between strain and
stress
 Can hold strain under DC
activation
 Glass transition temperature is
inadequate for low-temperature
actuation task
 Induces relatively large
actuation force
 High temperature applications
are limited by Curie temperature.
Table 1. Advantages and disadvantages of EAP

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APPLICATIONS:
Artificial Muscles:
EAPs hold promise for becoming the artificial
muscles of the future.
The elastomer employed is often a silicone
or acrylic elastomer, sometimes loaded with
heavy particles such as TiO2 to increase
the dielectric constant.
Electrodes are made of conductive C or Ag pastes,
spin-coated conductive rubbers, sprayed graphite particles.
Fig. 20 Elastic muscle

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Fig. 21 Boot heel generator

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Fig. 22 EAP used in wipers

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References
1) Madden, J.D.W.; Vandesteeg, N.A.; Anquetil, A.; Madden, P.G.A.; Takshi, A.;
Pytel, R.Z.; Lafontaine, S.R.; Wieringa, P.A.; Hunter, I.W. Artificial muscle
technology: Physical principles and naval prospects. IEEE J. Ocean. Eng. 2004, 29,
706–728.
2) Shahinpoor, M. Ionic polymer-conductor composites as biomimetic sensors, robotic
actuators and artificial muscles—A review. Electrochim. Acta 2003, 48, 2343–2353.
3)Bar-Cohen, Y. Biomimetics using electroactive polymers (EAP) as artificial
muscles—A review. J. Adv. Mater. 2006, 38, 3–9.
4)O’Halloran, A.; O’Malley, F.; McHugh, P. A review on dielectric elastomer
actuators, technology, applications, and challenges. J. Appl. Phys. 2008, 104.
5)Tondu, B. Artificial muscles for humanoid robots. In Humanoid Robots: Human-like
Machines; Hackel, M., Ed.; Itech: Vienna, Austria, 2007; Chapter 5; pp. 642–677.
6) Bertrand Tondu. What Is an Artificial Muscle? A Systemic Approach. Actuators
2015, 4(4), 336-352;

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