professor: dr. cheng-hsien liu ( 劉承賢教授 ) student: han-yi chen ( 陳翰儀 ) student id:...

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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


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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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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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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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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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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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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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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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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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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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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Thank you for Thank you for your attention!!your attention!!

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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.

professor: dr. cheng-hsien liu ( 劉承賢教授 ) student: han-yi chen ( 陳翰儀 ) student id:...

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