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11
Professor: Dr. Cheng-Hsien Liu (劉承賢教授 )
Student: Han-Yi Chen (陳翰儀 )
Student ID: 9735506
Date: 2009.11.10
Sensing and Actuation in Miniaturized Systems
Mass-production-oriented Ionic Polymer Actuator Based on Engineered Material Structure
Author: N. Nagai, T. Kawashima, J. OhsakoSony Corporation, Kitashinagawa Shinagawa-ku, Tokyo, JAPAN
2
Han-Yi Chen, NEMS, NTHU, 11/10/2009
2OutlineOutline
Introduction
Experiments and results
Bending mechanism
Conclusions
• Applications of ionic polymer actuator• Advantages and issues of ionic polymer actuator• New ionic polymer actuator
• Theory• Verification
• Structure• Manufacturing process• Basic characteristics
References
Electrode ElectrodeIon conductive polymer
-
-+
+
IntroductionIntroduction
4
Han-Yi Chen, NEMS, NTHU, 11/10/2009
4
Applications:
Artificial muscle
Biomimetic sensors
Biomimetic actuators
Advantages:
High performance in displacement or output force
Light weight
Flexibility
Issues:
Inefficiency of production process
High cost of materials
Ionic Polymer ActuatorIonic Polymer Actuator
Ref.: http://www.robotworld.org.tw/index.htm?pid=10&News_ID=1557
High performance High productivity Simple process Common instrument
High performance High productivity Simple process Common instrument
New ionic polymer actuator
Experiments and ResultsExperiments and Results
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Han-Yi Chen, NEMS, NTHU, 11/10/2009
6
Carbon electrodeCarbon electrode
Structure and Manufacturing ProcessStructure and Manufacturing Process
Ion-exchange polymer membrance (perfluorosulfonic acid polymer & ionic liquid)
Carbon electrode (fine carbon particles & perfluorosulfonic acid polymer & ionic liquid)
Metal
Metal
Ion-exchange polymer
membrance
Ion-exchange polymer
membrance Carbon electrodeCarbon
electrode
MetalMetal
Ion exchange polymer
dispersion
Ion exchange polymer
dispersion
Carbon powderCarbon powder
Ionic liquidIonic liquid
Zircon beadsZircon beads Spray coating process
Ion-exchange membranceCarbon electrodeCarbon electrode
Structure
Manufacturing process
Heating & pressing
Perfluorosulfonic acid polymer SEM cross section view
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Han-Yi Chen, NEMS, NTHU, 11/10/2009
7 Basic Characteristics (1)Basic Characteristics (1)
Displacement
15 mm
Time (sec)
Dis
pla
ce
me
nt
(mm
)
0 500 1000 1500 2000 2500
65
4
3
6
2
1
0
-1
-2
-3
Time (sec)
Dis
pla
ce
me
nt
(mm
) 5
4
3
6
2
1
00 5 10 15 20 25 30
Bending motion of the actuator (2 V, 0.1 Hz)Bending motion of the actuator (2 V, 0.1 Hz) Displacement of an actuator under applied constant voltage 2 V
Displacement of an actuator under applied constant voltage 2 V
0 to 30 sec0 to 30 sec
0 to 2000 sec0 to 2000 sec
Air
The actuator bends to one side by applying constant positive voltage and bends to the other side if change the voltage to negative
The displacement at 30 s after applying voltage 2.0 V was about 5 mm.
After 30 s the displacement began to decrease gradually and finally it reversed its movement and bent to the other side regarding its initial position.
The actuator bends to one side by applying constant positive voltage and bends to the other side if change the voltage to negative
The displacement at 30 s after applying voltage 2.0 V was about 5 mm.
After 30 s the displacement began to decrease gradually and finally it reversed its movement and bent to the other side regarding its initial position.
W: 2 mmL: 30 mm
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Han-Yi Chen, NEMS, NTHU, 11/10/2009
8 Basic Characteristics (2)Basic Characteristics (2)
Time (sec)
0 0.2 0.4 0.6 0.8 10
0.050.1
0.15
0.20.25
0.30.35
0.40.45
0.5
Dis
pla
ce
me
nt
(mm
)
10 mA
5 mA
1 mA
Displacements under applied constant currents
Displacements under applied constant currents
Dependence of output force on applied constant voltage
Dependence of output force on applied constant voltage
The displacement is in proportion to the period of applying constant current.
The displacement is in proportion to the period of applying constant current.
The output force was increased as applying voltage, and the force was over 4 mN at 2.0 V.
The output force was increased as applying voltage, and the force was over 4 mN at 2.0 V.
Applied Voltage (V)0 0.5 1 1.5 2 2.5
0
0.1
0.2
0.3
0.4
0.5
Ou
tpu
t F
orc
e (
gf)
Bending MechanismBending Mechanism
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Han-Yi Chen, NEMS, NTHU, 11/10/2009
10TheoryTheory
Bending model for an ionic polymer actuator
(a) Status without applying voltage(a) Status without applying voltage
(b) Initial motion of ions and
bending
(b) Initial motion of ions and
bending
(c) Bending after most of cations
moved
(c) Bending after most of cations
moved
The motion of ionic polymer actuator:
Initial fast bending: different moving speed
Subsequent slow bending to inverse direction: different size
Cations move much faster than anions
Cations move much faster than anions
Anions is muchlarger than cations
Anions is muchlarger than cations
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Han-Yi Chen, NEMS, NTHU, 11/10/2009
11Verification (1)- Verification (1)- Verify the Difference of Speed Between Ions
A test piece for measuring potential distributionA test piece for measuring potential distribution Transition of potential distribution after applying 2V
Transition of potential distribution after applying 2V
- +Ion conductive polymer
Carbon electrode Carbon electrode
Ionic liquid added section
Au plated solid electrodes
2 V
Base
50 µm
-+
0 1 2 3 4 5 6 7 8 9 10
< 0.5 V< 0.5 V
~ 1 V~ 1 V
+
-
+-
At 0 s: potential transition is at the center: slight shift on the distribution of ionic liquid.
At 0 s: potential transition is at the center: slight shift on the distribution of ionic liquid.
At 1000 s: potential transition moved to neighborhood of both carbon electrodes: electric double layer formed by ionic liquid at the carbon electrode.
At 1000 s: potential transition moved to neighborhood of both carbon electrodes: electric double layer formed by ionic liquid at the carbon electrode.
At 6000 s: the electric double layer formed by cations is almost completed and potential transition at this point is close to 1V. Whereas the electric double layer formed by anions is not completed and the potential transition is less than 0.5V.
At 6000 s: the electric double layer formed by cations is almost completed and potential transition at this point is close to 1V. Whereas the electric double layer formed by anions is not completed and the potential transition is less than 0.5V.
Proof: moving speed of cations is faster than anion. Proof: moving speed of cations is faster than anion.
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Han-Yi Chen, NEMS, NTHU, 11/10/2009
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Carbon electrode Carbon electrodeIon conductive polymer
Ionic Liquid added section
-
-+
+
Verification (2)- Verification (2)- Estimate Moving Speed of Ions
A test piece for measuring charging currentA test piece for measuring charging currentCharging current of a test piece at
applying constant voltage 2VCharging current of a test piece at
applying constant voltage 2V
(a) The actuator electrically behaves as a capacitor with wide gap and the current is small sharp peak at initial stage.
The speed of cation: 50 µm / 2000 s = 25 nm/sThe speed of anion:50 µm / 40000 s = 1.3 nm/sThe cation is about 20 times
faster than the anion.
The speed of cation: 50 µm / 2000 s = 25 nm/sThe speed of anion:50 µm / 40000 s = 1.3 nm/sThe cation is about 20 times
faster than the anion.
Current by faster ion (cation)Current by faster ion (cation)
Current by slower ion (anion)Current by slower ion (anion)
2000 s
(a)
(b)
(c)
(d)
(b) Then the charging current keeps small value while the ions migrate through the ion exchange polymer.
(c) Finally the ions arrive at carbon electrode and begin to form an electric double layer. The current increases rapidly at that point as capacitance increases simultaneously.
(d) After accomplishing the electric double layer, the charging current rapidly decreases and begins to keep small value again.
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Han-Yi Chen, NEMS, NTHU, 11/10/2009
13Verification (3)- Verification (3)- Factors of Different Ion Speed
Carbon electrode Carbon electrodeIon conductive polymer
Ionic Liquid added section
-
-+
+
A test piece for measuring charging currentA test piece for measuring charging current
The factors to make anion speed slow: Ion size: the size of anion is about two times bigger than cation Interaction between anion and functional group: (1) Perfluorosulfonic acid polymer is a cation exchange polymer so that anions can not pass through the actuator basically. (2) The anions could pass by applying enough voltage. The threshold voltage was about 100 mV. But the moving speed is very slow because the anions is scattered by functional group.
ConclusionsConclusions
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Han-Yi Chen, NEMS, NTHU, 11/10/2009
15
The author developed practical designed polymer actuator with high performance in the air.
They clarify a bending mechanism of their polymer actuator that the differences in size and in moving speed between cations and anions cause bending. They think that interaction between ion and functional group of polymer decides the size and the moving speed of ions.
The polymer actuator they developed is easy to change the materials and the process so that they think this actuator can improve the performance further more.
This actuator will make lighter and smaller device possible in the market in future.
ConclusionsConclusions
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Han-Yi Chen, NEMS, NTHU, 11/10/2009
16ReferencesReferences
[1] K. Oguro, Y. Kawami, H. Takenaka “Bending of an ion-conducting polymer film-electrode composite by an electric stimulus at low-voltage.” J. Micromach. Soc. 5 (1992) 27–30.
[2] M. Shahinpoor, Y. Bar-Cohen, J. Simpson, J. Smith “Ionic polymermetal composites (IPMCs) as biomimetic sensors, actuators and artificial muscles—a review. ” Smart Mater. Struct. 7 (1998) R15-R30.
[3] Barbar J. Akle, Matthew D. Bennett, Donald J. Leo “High-strain ionomeric–ionic liquid electroactive actuators” Sensors and Actuators A 126 (2006) 173–181
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Han-Yi Chen, NEMS, NTHU, 11/10/2009
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Thank you for Thank you for your attention!!your attention!!
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Han-Yi Chen, NEMS, NTHU, 11/10/2009
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The effects of electrode expansion:Mainly determined by original ion size and by repulsive
force between same ions.The interaction between ions and functional group. But
the amount of ions is much larger than functional group at the electrode.