Phys 150 - Thor - Artificial Muscles - Paul K....

Artificial MusclesArtificial Muscles

Douglas ThorDouglas Thor

Human MusclesHuman Muscles

3 types of muscle3 types of muscle Skeletal Skeletal –– connects bones, voluntary, striated connects bones, voluntary, striated Smooth Smooth –– involuntary involuntary Cardiac Cardiac –– heart muscle, involuntary, striated heart muscle, involuntary, striated

http://en.wikipedia.org/wiki/Muscles

Skeletal MusclesSkeletal Muscles These are the type of musclesThese are the type of muscles

that Artificial Muscles emulatethat Artificial Muscles emulate Striated Striated –– contain sarcomeres contain sarcomeres

and are packed into highly-and are packed into highly-regular arrangementsregular arrangements

Generally come in pairs Generally come in pairs –– an anagonist and an antagonistagonist and an antagonist i.e. Biceps Brachii and Tricepsi.e. Biceps Brachii and Triceps

BrachiiBrachii

http://en.wikipedia.org/wiki/Skeletal_muscle

Why develop Artificial Muscles?Why develop Artificial Muscles?

Uses in nano- to medium scale roboticsUses in nano- to medium scale robotics Bionics and Robotic ProstheticsBionics and Robotic Prosthetics The FutureThe Future……

Hope to be adapted for implants orHope to be adapted for implants orreplacement muscles to cure problems suchreplacement muscles to cure problems suchas muscular atrophy, certain types ofas muscular atrophy, certain types ofparalysis, or muscle death.paralysis, or muscle death.

Possible uses in artificial heartsPossible uses in artificial hearts

Artificial MusclesArtificial Muscles

3 primary types:3 primary types: Pneumatic Artificial Muscles (PAMs)Pneumatic Artificial Muscles (PAMs) Electroactive Polymers (EAPs)Electroactive Polymers (EAPs) Carbon Nanotube Muscles (Carbon Nanotube Muscles (CNMsCNMs))

http://en.wikipedia.org/wiki/Artificial_Muscle. http://en.wikipedia.org/wiki/Pneumatic_artificial_muscles. AlievAliev, , et alet al. Science 323, 1575 (2009). Science 323, 1575 (2009)

Pneumatic Artificial MusclesPneumatic Artificial Muscles

First attempt at artificial muscles (1950s)First attempt at artificial muscles (1950s) Uses pressurized air or Nitrogen toUses pressurized air or Nitrogen to

expand and contract a membraneexpand and contract a membrane

http://en.wikipedia.org/wiki/Pneumatic_artificial_muscles

Pneumatic Artificial MusclesPneumatic Artificial Muscles AdvantagesAdvantages

Force-extension relationship is similar toForce-extension relationship is similar tohuman skeletal muscleshuman skeletal muscles

Good for use in medium scale roboticsGood for use in medium scale robotics DisadvantagesDisadvantages

Nonlinear systemNonlinear system Gas is compressibleGas is compressible Requires large and heavy electric valves andRequires large and heavy electric valves and

air compressorair compressor

http://en.wikipedia.org/wiki/Pneumatic_artificial_muscles

Electroactive Polymers (EAPs)Electroactive Polymers (EAPs)

Most common type of Artificial MuscleMost common type of Artificial Muscle Two types of Electroactive Polymers:Two types of Electroactive Polymers:

Dielectric ElastomersDielectric Elastomers Ionic Electroactive PolymersIonic Electroactive Polymers

Used as actuators, sensors, and wellUsed as actuators, sensors, and wellsuited for small to medium scale roboticssuited for small to medium scale robotics

Strains usually 10-35%, max 300%Strains usually 10-35%, max 300% First used in the early 90First used in the early 90’’ss

http://en.wikipedia.org/wiki/Electroactive_polymers

Dielectric ElastomersDielectric Elastomers

Squishy CapacitorSquishy Capacitor High voltage, little to no current neededHigh voltage, little to no current needed Key Physics:Key Physics:

PoissonPoisson’’s Ratios Ratio Capacitor EquationsCapacitor Equations Lorentz ForceLorentz Force


2

2

2

Q A

V d

Fd A

V d

F V

A d

!

!

!

=

=

=

Page oPage o’’ Physics PhysicsQ A

CV d

!= =

trans x

axial y

! !"

! != # = #

Poisson’s Ratio

(F Q E v B= + ! )

FQE Q

E= " =

0r! ! !=

( )1 2V L

V L!

" "= #

My Brain, http://en.wikipedia.org/wiki/Electroactive_polymers, http://en.wikipedia.org/wiki/Poisson%27s_ratio

Dielectric ElastomersDielectric Elastomers

Made from primarily silicones and acrylicMade from primarily silicones and acrylic Requirements for a good Elastomer:Requirements for a good Elastomer:

Low stiffnessLow stiffness High dielectric constantHigh dielectric constant High electrical breakdown voltageHigh electrical breakdown voltage

Can be arranged in a multitude of differentCan be arranged in a multitude of differentways to achieve various resultsways to achieve various results Cylinders, diaphragms, stacks, etc.Cylinders, diaphragms, stacks, etc.

http://en.wikipedia.org/wiki/Dielectric_elastomers

Ionic EAPsIonic EAPs Movement caused byMovement caused by

displacement of ionsdisplacement of ionswithin the polymerwithin the polymer

Requires lowerRequires lowervoltage than avoltage than adielectric elastomer,dielectric elastomer,but requires morebut requires morepowerpower

Constant power isConstant power isneeded to maintain aneeded to maintain agiven positiongiven position


Superelastic Carbon NanotubeSuperelastic Carbon NanotubeAerogel Muscles (CNMs)Aerogel Muscles (CNMs)

Published in 2009Published in 2009 First description of nanotube-nanotubeFirst description of nanotube-nanotube

interaction was by Kim and interaction was by Kim and Leiber Leiber in 1999in 1999 Nanotube tweezers actuated by a potentialNanotube tweezers actuated by a potential

differencedifference Very stiff in one direction, superelastic inVery stiff in one direction, superelastic in

other two directions.other two directions.

Aliev, et al. Science 323, 1575 (2009)

Carbon Nanotube MusclesCarbon Nanotube Muscles

Nanotube sheets made by drawingNanotube sheets made by drawingnanotubes from a nanotubes from a ““forestforest”” Held together like twine or yarnHeld together like twine or yarn

Aliev, et al. Science 323, 1575 (2009), http://www.wired.com/wiredscience/2009/03/nanomuscle/

A high voltage (kV) is applied to the endsA high voltage (kV) is applied to the endsof the sheetof the sheet width expansion at center (up to 220%)width expansion at center (up to 220%) length contraction (<3%)length contraction (<3%)

Madden. Science, 323, 5921. Aliev, et al. Science 323, 1575 (2009)


Carbon Nanotube MusclesCarbon Nanotube Muscles A: 50mm x 2mm

nanotube sheet B: same sheet, 5kV

applied at ends,~220% width increaseat center

C: 25mm x 2mm, 3kVapplied, 1500K



Maximum CharacteristicsMaximum Characteristics Expansion: 220%Expansion: 220% Expansion Rate: 3.7 x 10Expansion Rate: 3.7 x 1044% per second% per second

Natural muscles: 10% per secondNatural muscles: 10% per second

Operating Temp: 80 to 1900KOperating Temp: 80 to 1900K PoissonPoisson’’s Ratio: 15 (most materials <.5)s Ratio: 15 (most materials <.5)


Carbon Nanotube MusclesCarbon Nanotube Muscles Other Notes:

Actuation can be “frozen” by laying expanded sheet on asubstrate of gold-coated silicon and letting van der Waalsbonding hold it in place.

First use of electrostatic attraction and repulsion betweenFirst use of electrostatic attraction and repulsion betweennanotubes nanotubes –– 1999 1999

Can generate 30 times the force per unit area of natural muscle

CNM #1CNM #1 Demo with CG animation Demo with CG animation CNM #2CNM #2 Laser Diffraction patternLaser Diffraction pattern CNM #3CNM #3 Drawing the nanotubesDrawing the nanotubes CNM #4CNM #4 Applied voltageApplied voltage

http://www.wired.com/wiredscience/2009/03/nanomuscle/

SummarySummary

Three types of artificial muscles:Three types of artificial muscles:Pneumatic, Electroactive, and CarbonPneumatic, Electroactive, and CarbonNanotubeNanotube

Currently useful in robotics, hope to beCurrently useful in robotics, hope to beused as replacement musclesused as replacement muscles

Most advanced form are Carbon NanotubeMost advanced form are Carbon NanotubeMusclesMuscles

Thank YouThank You

ReferencesReferences http://en.wikipedia.org/wiki/Muscleshttp://en.wikipedia.org/wiki/Muscles http://en.wikipedia.org/wiki/Electroactive_polymershttp://en.wikipedia.org/wiki/Electroactive_polymers http://www.wired.com/wiredscience/2009/03/nanomuscle/http://www.wired.com/wiredscience/2009/03/nanomuscle/ ““Stiffer Than Steel." John D. W. Madden. Science, 323, 5921, March 19,Stiffer Than Steel." John D. W. Madden. Science, 323, 5921, March 19,

2009. DOI: 10.1126/science.11711692009. DOI: 10.1126/science.1171169 ““Giant-Stroke, Superelastic Carbon Nanotube Aerogel Muscles.Giant-Stroke, Superelastic Carbon Nanotube Aerogel Muscles.”” Ali E. Aliev, Ali E. Aliev,

et alet al. Science 323, 1575 (2009); DOI: 10.1126/science. 1168312. Science 323, 1575 (2009); DOI: 10.1126/science. 1168312 ““Nanotube Nanotube NanotweezersNanotweezers..”” Philip Kim and Charles M. Philip Kim and Charles M. LeiberLeiber. Science, 286,. Science, 286,

5447, pp. 2148-2150, December 10, 1999. DOI:5447, pp. 2148-2150, December 10, 1999. DOI:10.1126/science.286.5447.214810.1126/science.286.5447.2148

http://ndeaa.jpl.nasa.gov/nasa-nde/lommas/eap/EAP-armwrestling.htmhttp://ndeaa.jpl.nasa.gov/nasa-nde/lommas/eap/EAP-armwrestling.htm http://www.azom.com/details.asp?ArticleID=885http://www.azom.com/details.asp?ArticleID=885 http://en.wikipedia.org/wiki/Pneumatic_artificial_muscleshttp://en.wikipedia.org/wiki/Pneumatic_artificial_muscles http://mech.vub.ac.be/multibody/topics/pam.htmhttp://mech.vub.ac.be/multibody/topics/pam.htm http://en.http://en.wikipediawikipedia..org/wiki/Carbon_nanotube_actuatorsorg/wiki/Carbon_nanotube_actuators

And any citations referenced by the aforementioned articlesAnd any citations referenced by the aforementioned articles

QuestionsQuestions

1. Which was the first type of artificial1. Which was the first type of artificialmuscle?muscle?

a. a. electroactive electroactive polymerspolymersb. carbon nanotubeb. carbon nanotubec. pneumaticc. pneumaticd. unicorn muscled. unicorn musclee. none of the abovee. none of the above

QuestionsQuestions

2. A Dielectric Elastomer Electroactive2. A Dielectric Elastomer ElectroactivePolymer is similar toPolymer is similar to……

a. a fluffy bunnya. a fluffy bunnyb. a soft resistorb. a soft resistorc. a stretchable inductorc. a stretchable inductord. a squishy capacitord. a squishy capacitore. carbon nanotubese. carbon nanotubes

Phys 150 - Thor - Artificial Muscles - Paul K....

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