Table Of ContentElectroactivity in Polymeric Materials
Lenore Rasmussen
Editor
Electroactivity in Polymeric
Materials
123
LenoreRasmussen
Ras Labs,LLC, Intelligent Materials forProsthetics and Automation
Plasma Surface ModificationExperiment
US Department ofEnergy’s Princeton
Plasma PhysicsLaboratory atPrincetonUniversity
Room L-127,100Stellarator Road
Princeton
NJ08543
USA
ISBN 978-1-4614-0877-2 e-ISBN978-1-4614-0878-9
DOI 10.1007/978-1-4614-0878-9
SpringerNewYorkHeidelbergDordrechtLondon
LibraryofCongressControlNumber:2012932404
(cid:2)SpringerScience+BusinessMediaNewYork2012
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Preface
Thethoughtsofmakingatheoreticaltextbookstylebookinelectroactivematerials
began when I started getting more students in the laboratory. When new students
jointheproject,Iinvariablygivethemastackofjournalarticlestowadethrough,
so began thinking how helpful it would be to give them a concise book to start
with.Thisbookisdesignedasastartingpoint,particularlytogetahandleon‘‘how
does electroactive movement happen?’’
The goal of this book was to capture the theory—how electroactivity works—
balanced with applications—how can electroactivity be used, drawing inspiration
from our manmade mechanical world and the natural worldaround us. This book
takes a small step at capturing the fascinating field of electroactive materials and
actuators. I’m already putting thoughts together on how to make the second
volume even more informative while retaining concision and clarity.
The Artificial Muscle Project draws people from a variety of disciplines.
Indeed,thefieldofelectroactivityisextremelyinterdisciplinary.Caseinpoint:for
my first patent in this area, the examiner from the USPTO called me. Evidently,
theyhadseveralmeetingstryingtodecidewhichpatentclassificationcodeitcame
under—chemistryorelectricalengineering?Sotheyresolvedthematterbyputting
the question to me. We chatted and I agreed that it was on the fence between the
two areas, but since my background was stronger in chemistry, the main classi-
fication was placed in class 523/113, synthetic resins, subclass composition suit-
able for use as tissue or body member replacement, restorative, or implant.
Fundamentally, the thorough understanding of electroactivity is important
because of the ability of bending, contraction, and expansion to produce smooth,
controllable, life-like biomimetic motion. By combining electroactive materials
with fuel cells and other technologies, electroactive actuation and its reciprocal
action can also provide for extremely energy efficient motion, energy generation,
and energy harvesting. Electroactivity offers new ways of thinking about and
configuring devises, machines, implants, and surfaces, for futuristic mobility by
land, air, and sea.
v
Acknowledgments
The editor would like to thank everyone who contributed to this effort, both for
advancing the field of electroactivity as well as those who helped with the prep-
arationofthisbook.Theeditorwouldliketothanktheotherco-authors:Prof.Iain
Anderson and his group including Todd Gisby and Ben O’Brien; Prof. Mohsen
Shahinpoor and his group including Yousef Bahramzadeh; Prof. Qibing Pei and
hisgroup includingPaulBrochu; Dr.RoyKornbluh,Ron Pelrine,HarshaPrahad,
Annjoe Wong-Foy, Brian McCoy, Susan Kim, Joseph Eckerle, and Tom Low of
SRI International; and others who have made so many strides in the field of
electroactivity: Dr. Yoseph Bar-Cohen, Profs. Yoshihito Osada and Jian Ping
Gong, Prof. Toyoichi Tanaka, Prof. John Madden, Prof. Elizabeth Smela,
Prof.FedericoCarpi,Prof.GiovanniPioggia,Prof.DanilodeRossi,Prof.Cynthia
Breazeal, Dr. Emilio Calius, Prof. Selahattin Ozcelik, Prof. Alexie Khokhlov,
Prof. Donald Leo, Prof. Timothy E. Long, Prof. Roger Moore, Prof. Qiming
Zhang,andmany,manyothers.Together,allofuscollectively,aremakingscience
fiction a reality.
Paramount to the success of this book was the United States Department of
Energy’s Princeton Plasma Physics Laboratory at Princeton University. I would
like to personally thank Lewis Meixler, Charles Gentile, George Ascoine, Yevg-
eny Raitses, Eliot Feibush, Philip Efthimion, Adam Cohen, Stewart Prager,
Anthony DeMeo, Kitta McPherson, Patricia Wieser, Jim Taylor, Stephan
Jurczynski, Carl Tilson, Sue Hill, Gary D’Amico, William Zimmer, John
Trafalski, and many others for their support, encouragement, expertise, and state-
of-the-artscientificcapabilities.Iwouldalsoliketothanktheprofessorsandtheir
laboratories at Princeton Universitythat have helped so much with this endeavor:
Prof.RobertCavaandDr.AnthonyWilliamsforhelpinthesolidstatelaboratory;
Prof. Steven L. Bernasek and Dr. Esta Abelev for their help with X-ray photo-
electron spectroscopy; and Jane Woodall and Prof. Nan Yao for their help with
scanning electron microscopy at the Image and Analysis Center. I would like to
thankFrankCozzarelli,Jr.,forhispatentexpertiseandinsights.Aspecialheartfelt
thanks goes to Thomas Brown of the Federal Laboratory Consortium.
vii
viii Acknowledgments
I would like to thank all the interns and continuing education teachers who
have contributed to the Artificial Muscle Project over the years: Alice Kirk,
ErichSchramm,CarlJ.Erickson,DavidSchramm,KelseyPagdon,DanPearlman,
Kevin Mulally, Sarah Newbury, Aparna Panja, Victoria Jones, and my two sons,
who had no choice but to dragged into the business, Paul and Lars Rasmussen.
Your laboratory technique, persistence, inquiring minds, and questions that made
me think and re-think, made this project a success. I would also like to thank my
youngest son, Carl Rasmussen, for his curiosity in the greater world around us.
Many heartfelt thanks to Barbara Jones for her proofing abilities, translation
abilities, and wording suggestions.
I would like to thank Dean Kathryn E. Uhrich of Rutgers University and
Prof. James E. McGrath, Prof. Garth L. Wilkes, and Prof. Eugene M. Gregory of
Virginia Tech, for all their help with my education, critical thinking, laboratory
technique, and ability to synthetically tailor materials, all of which has served so
wellinacademiaandindustry.AspecialthanksgoestoDanandJudiMcGuirefor
providing a home away from home while completing my education.
Last but certainly not least, I would like to thank the rest of my family for all
their love, support and encouragement in this endeavor: my husband Henrik
T. Rasmussen for his love and devotion, my mother Winola H. Carman for her
continualencouragement,mybrothersandsister-in-lawPaulCarman,Nathanand
Sally Carman, my father R. Wayne Carman, and my beautiful family through
marriage, Jørgen and Ingrid Rasmussen, Tom and Linda Rasmussen, and Morten
and Carolin Rasmussen. Desperation may be the mother of invention, but
encouragement is the foundation of creativity.
Contents
1 Dielectric Elastomers for Actuators and Artificial Muscles . . . . . . 1
Paul Brochu and Qibing Pei
2 Modeling of IPMC Guide Wire Stirrer
in Endovascular Surgery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Yousef Bahramzadeh and Mohsen Shahinpoor
3 From Boots to Buoys: Promises and Challenges
of Dielectric Elastomer Energy Harvesting . . . . . . . . . . . . . . . . . . 67
Roy D. Kornbluh, Ron Pelrine, Harsha Prahlad, Annjoe Wong-Foy,
Brian McCoy, Susan Kim, Joseph Eckerle and Tom Low
4 Theory of Ionic Electroactive Polymers Capable
of Contraction and Expansion–Contraction Cycles . . . . . . . . . . . . 95
Lenore Rasmussen
5 Touch Sensitive Dielectric Elastomer Artificial Muscles. . . . . . . . . 131
Todd Gisby, Ben O’Brien and Iain A. Anderson
Appendices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
Appendix A. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
Appendix B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
ix
Chapter 1
Dielectric Elastomers for Actuators
and Artificial Muscles
Paul Brochu and Qibing Pei
Abstract Anumberofelectroactivepolymershavebeenexploredfortheiruseas
artificial muscles. Among these, dielectric elastomers appear to provide the best
combination of properties for true muscle-like actuation. Dielectric elastomers
behaveascompliantcapacitors,expandinginareaandshrinkinginthicknesswhen
a voltage is applied. Materials combining very high energy densities, strains and
efficiencies have been known for some time. To date, however, the widespread
adoption of dielectric elastomers has been hindered by premature breakdown and
therequirementforhighvoltagesandbulkysupportframes.Recentadvancesseem
poisedtoremovetheserestrictionsandallowfortheproductionofhighlyreliable,
high-performance transducers for artificial muscle applications.
Keywords Dielectric elastomer (cid:2) Electroactive polymer (cid:2) Bistable electroactive
polymers (cid:2) Actuator (cid:2) Transducer (cid:2) Artificial muscle (cid:2) DE (cid:2) EAP (cid:2) BSEP
1.1 Introduction
The ability to mimic the muscles in our own human bodies, both for the
advancement in our well-being and for our amusement, has been a topic of great
interest for some time. Natural muscle has a number of properties that make it
difficulttomatchintermsofperformance.Theenergydensityofmuscleisonthe
order of 150 J kg-1 and can peak at around 300 J kg-1 [1], while displacements
P.Brochu(cid:2)Q.Pei(&)
DepartmentofMaterialsScienceandEngineering,TheHenrySamueli
SchoolofEngineering,UniversityofCalifornia,420WestwoodPlaza,
LosAngeles,CA90095-1595,USA
e-mail:[email protected]
L.Rasmussen(ed.),ElectroactivityinPolymericMaterials, 1
DOI:10.1007/978-1-4614-0878-9_1,
(cid:2)SpringerScience+BusinessMediaNewYork2012
2 P.BrochuandQ.Pei
are relatively large with typical strains ranging from 20 to 40% and peaking at
100% [2–4]. By these measures alone, electromagnetic (EM) motors and com-
bustion engines should be able to match or exceed the performance of natural
muscle [5]. However, as it is made obvious by current leading-edge robots (e.g.,
Honda’s Asimo) [6], the real world performance of conventional-actuator-based
roboticsislimited[2,7].Theshortcomingliesonseveralfronts.Firstisthepower
supply: natural muscle relies on chemical energy that is supplied to living
organisms through the ingestion offood, while EM motors rely on heavy battery
pack and capacitor banks that must be recharged frequently. These large
power sources contribute to the overall mass of the robotic device and reduce
the effective energy density as well as limit range and mobility. Second is the
requirementforgearingsystems:EMmotorsoperatebestathighrotationalspeeds;
these must be reduced significantly through the use of gearing systems that can
significantly increase mass and reduce energy density. Third is the ability to
recoverenergy:tendonandflesh,aswellasmuscleitself,arecapableofabsorbing
and storing a large percentage of the impact energy that can be translated back to
motion. Additionally, muscles possess other salient properties that allow them to
operate as motors, brakes, springs, and struts, permitting better stability control
and impact energy absorption [8]. EM motors also generate more noise and heat
thannaturalmuscle,which isnotwelcomeforcertain applications,andcannotbe
effectively operated in large magnetic fields.
Pneumatic systems operate linearly like natural muscle; pneumatic artificial
muscles(McKibbenartificialmuscles)inparticularareintrinsicallycompliantand
can thus provide the ‘‘give’’ that natural muscle attains. Unfortunately, these
systemsrequireaircompressorsthatareneitherlightnorsmall,andtheirresponse
speed is limited by the ability to pump air into and out of the actuators.
Several ‘‘smart materials’’ have been proposed as artificial muscles. These
include shape memory alloys (SMA), magnetostrictive alloys (MSA), and piezo-
electrics [2, 9]. SMAs are capable of producing relatively large linear displace-
ments and can be actuated relatively quickly using resistive heating. What limits
their applicability to artificial muscle applications is the time it takes to cool the
alloyandreturntotherestposition.Inordertoobtaingoodoperatingfrequencies,
theSMAmustbeactivelycooled,increasingthebulk,complexityandcostofthe
system. Magnetostrictive alloys and piezoelectric ceramics both suffer from
small strains and high stiffness. These materials are thus not particularly suited to
artificial muscle applications.
Polymers present an interesting alternative to conventional technologies. They
possess inherent compliance, are lightweight, and are generally low cost. Elec-
troactivepolymers(EAPs)areanemergingtypeofactuatortechnologywhereina
lightweightpolymerrespondstoanelectricfieldbygeneratingmechanicalmotion
[1, 10, 11]. Their ability to mimic the properties of natural muscle has garnered
them the moniker ‘‘artificial muscle,’’ though the term electroactive polymer
artificial muscle (EPAM) is more appropriate and descriptive.
Theconceptofelectroactivepolymerscanbedatedbackto1880inapaperby
Roentgen[12].Inhisexperiments,heobservedthatafilmofnaturalrubbercould
