special topic electroactive polymers...
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Special TopicElectroactive Polymers (EAPs)
Prof. Seung Tae CHOI ( )
22 SCHOOL OF MECHANICAL ENGINEERINGLECTURER: PROF. SEUNGTAE CHOI
Why are Electroactive Polymers (EAPs)
Transducers are a critical part ofMEMS/MOEMS devicesEAPs have unique characteristicsand bring new possibilities
MECHANICAL WORKENERGY
(ELECTRICAL)
EAPE W
ACTUATOR
GENERATOR OR SENSOR
What’s wrong with current MEMS actuators?» Electrostatic – low forces, small
scale only (high tolerance), stiction» Electromagnetic – inefficient at small
scales» Piezoelectric – small strain, high
tolerances, more complex fabrication, Pb
» Thermal and Bubble – inefficient, not reversible (actuator only), relatively slow, proportional control difficult
» Shape Memory Alloy – inefficient, not reversible (actuator only), relative slow, complex fabrication, proportional control difficult
33 SCHOOL OF MECHANICAL ENGINEERINGLECTURER: PROF. SEUNGTAE CHOI
Many Types of EAPs
Artificial Muscle”
Electrostrictive Polymer
Dielectric Elastomer
IPMC
Conducting Polymers
GelsThermal and Others
Nanotubes
44 SCHOOL OF MECHANICAL ENGINEERINGLECTURER: PROF. SEUNGTAE CHOI
Electroactive Polymer (Artificial Muscle)
+ + + + + + + + + + +
Electronic EAP Ionic EAP
Electroactive Polymers
55 SCHOOL OF MECHANICAL ENGINEERINGLECTURER: PROF. SEUNGTAE CHOI
Ionic EAPs
Ionic Polymer Gel
Conductive Polymers and IPMC
66 SCHOOL OF MECHANICAL ENGINEERINGLECTURER: PROF. SEUNGTAE CHOI
Electronic EAPsElectrostrictive polymers
Piezoelectric polymers
77 SCHOOL OF MECHANICAL ENGINEERINGLECTURER: PROF. SEUNGTAE CHOI
(DIELECTRIC ELASTOMERS)
88 SCHOOL OF MECHANICAL ENGINEERINGLECTURER: PROF. SEUNGTAE CHOI
Dielectric Elastomer Actuators
E
EmaxEmax
99 SCHOOL OF MECHANICAL ENGINEERINGLECTURER: PROF. SEUNGTAE CHOI
V
Dielectric Elastomer Actuators
Desirable characteristics
But
110 SCHOOL OF MECHANICAL ENGINEERINGLECTURER: PROF. SEUNGTAE CHOI
Artificial Muscle for Micro Robots?
EAPs can behave a lot like a muscleMuscle is a spring damper systemand sensor in addition to a motor
http://www.britannica.com/science/skeletal-muscle
111 SCHOOL OF MECHANICAL ENGINEERINGLECTURER: PROF. SEUNGTAE CHOI
Bioinspired Electroactive Butterflies
112 SCHOOL OF MECHANICAL ENGINEERINGLECTURER: PROF. SEUNGTAE CHOI
(FLUORINATED FERROELECTRIC POLYMERS)
-phase
-phase
H
HH
FF H
F
F
H
HH
FF H
F
F
H
HH
FF H
F
F
H
HH
FF H
F
F
4.62 A
5.16 A
H
FF
H H
FF
H H
FF
H H
FF
H H
FF
H
FF
Electricfield
Heating/cooling
113 SCHOOL OF MECHANICAL ENGINEERINGLECTURER: PROF. SEUNGTAE CHOI
Ferroelectric PolymersPVDF = Polyvinylidene fluoride & P(VDF-TrFE) = Poly(vinylidenefluoride-trifluoroethylene)Ferroelectric behavior due to permanent electric dipoles
-phase
-phase
http://canopus.physik.uni-potsdam.de/research/limm/pvdfspin.gif
VDF TrFE
H
C
H
C
F F
C
H
C
F F
F
H
HH
FF H
F
F
H
HH
FF H
F
F
H
HH
FF H
F
F
H
HH
FF H
F
F
4.62 A
5.16 A
H
FF
H H
FF
H H
FF
H H
FF
H H
FF
H
FF
Melt
Solution
Poling at very high E
Annealing at very high P
Ultradrawing at high T
Drawing at low T
Annealing at high T
All TsEpitaxially on KBr
High P
(Possibly at high T?)High T
High P
MCB/DMF,Cyclohexanone
DMF, DMA, or DMSO
Cyclohexanone
Annealing at high T
(Possibly by annea
ling at high P)
Poling at very high E
Microstructure of PVDF or P(VDF-TrFE)
226 SCHOOL OF MECHANICAL ENGINEERINGLECTURER: PROF. SEUNGTAE CHOI
(RELAXOR FERROELECTRIC POLYMER ACTUATORS)
P
PP
P
P PPP
PP
P : Nanoscale paraelectric domain
: Nanoscale ferroelectric domain
Electric field off Electric field on
P
P P
P
227 SCHOOL OF MECHANICAL ENGINEERINGLECTURER: PROF. SEUNGTAE CHOI
Relaxor Ferroelectric Polymers
Polarizationhysteresis
P(VDF-TrFE-CFE) terpolymer actuator: The large strains associated with the conformation changes between the polar- and non-polar conformations in PVDF-based ferroelectric polymer can be used of to generate high electrostrictive strain
VDF TrFE CFE
H
C
H
C
F F
C
H
C
F F
F
-phase
-phase
H
HH
FF H
F
F
H
HH
FF H
F
F
H
HH
FF H
F
F
H
HH
FF H
F
F
4.62 A
5.16 A
H
FF
H H
FF
H H
FF
H H
FF
H H
FF
H
FF
H
C
H
C
F Cl
Electricfield
Heating/cooling
P
PP
P
P PPP
PP
P : Nanoscale paraelectric domain
: Nanoscale ferroelectric domain
Electric field off
Electric field on
P
P P
P
229 SCHOOL OF MECHANICAL ENGINEERINGLECTURER: PROF. SEUNGTAE CHOI
Piezotech FC™ & RT™ in Actuators
331 SCHOOL OF MECHANICAL ENGINEERINGLECTURER: PROF. SEUNGTAE CHOI
Biomimetic Varifocal Lens
Varifocal liquid lens
Hydraulic pressure eyesImaging system Human eye Cetacean eye
Eye shape Spherical eyecup Hemispherical eyecup
Lens Elliptic lens Spherical lens
Major optical power
Convex outer surface of cornea Strongly convex (spherical) lens
Change of focus
Change of the lens shape by ciliary muscle
Axial displacement of the lens due to changes in intraocular
pressure
Anatomy
Natural imaging systems
https://www.youtube.com/watch?v=bA-jDk3-Mgs
334 SCHOOL OF MECHANICAL ENGINEERINGLECTURER: PROF. SEUNGTAE CHOI
Operation of Varifocal Lens
• Wafer-Level Process: World-First• Thickness < 0.6 mm: World-Best
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