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					              ECE5320 Mechatronics
Assignment#01: Literature Survey on Sensors and Actuators

        Topic: Electroactive Polymers (EAP)
                or Artificial Muscles

                          Prepared by:
                         Roger Packham
         Dept. of Electrical and Computer Engineering
                     Utah State University
    E: rpackham@cc.usu.edu; F: (435)797-3054 (ECE Dept.)
                W: http://cc.usu.edu/~rpackham
                        3/11/2005
                                             Slide-2



                                      Outline
           –   Reference list
           –   To probe further
           –   Major applications
           –   Basic working principle illustrated
           –   A typical sample configuration in application
               (application notes)
           –   Major specifications
           –   Limitations and Future Outlook
           –   Where to buy, and how to fabricate your own.

1/4/2011               ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators
                                                    Slide-3



                                    Reference list
  • General History and Background
           – “Electroactive Polymers (EAP)” (Electrochemistry Encyclopedia)
               • http://electrochem.cwru.edu/ed/encycl/art-p02-elact-pol.htm
           – “Electric Flex,” (IEEE Spectrum, June, 2004) by Yoseph Bar-Cohen.
               • http://ndeaa.jpl.nasa.gov/ndeaa-pub/IEEE/ElectricFlux.pdf
  • Slightly More in Depth
     – “Polymer Actuators” P. Sommer-Larsen, The Danish Polymer Centre
               • http://uorganisk.kiku.dk/kurser/kemiidag/polymer_actuators.pdf
  • Journal Indexes, Videos, and Other Resources
           – Artificial Muscle Research Institute, University of New Mexico
               • http://www.unm.edu/~amri/




1/4/2011                      ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators
                                               Slide-4



                          To Explore Further
  • JPL's NDEAA Technologies Website – huge index of technical
    papers and links, including videos.
      http://ndeaa.jpl.nasa.gov/nasa-nde/lommas/aa-hp.htm
  • EAP Fabrication recipes – instructions to make your own EAP
      http://ndeaa.jpl.nasa.gov/nasa-nde/lommas/eap/EAP-recipe.htm
  • Electroactive Polymer Actuators as Artificial Muscles (SPIE Press,
    Bellingham, Wash., 2001), edited by Yoseph Bar-Cohen.




1/4/2011                 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators
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                          Major applications
  • Current applications:
           –   Camera lens wiper on spacecraft
           –   Muscle-like actuation
           –   Toys and education (see the first EAP toy – fish!                           )
           –   Catheter direction control
           –   MEMS devices
  • Future applications:
           –   Heart assist device (see a prototype movie here  )
           –   Low-voltage actuation
           –   Biological robotic movement (see human face here                                 )
           –   Braille computer monitor
           –   Acoustically active tile
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           List of the leading EAP materials
             Electronic EAP                                              Ionic EAP

 • Dielectric EAP
                                                     •       Carbon Nanotubes (CNT)
 • Electrostrictive Graft
                                                     •       Conductive Polymers (CP)
   Elastomers
                                                     •       ElectroRheological Fluids (ERF)
 • Electrostrictive Paper
                                                     •       Ionic Polymer Gels (IPG)
 • Electro-Viscoelastic
                                                     •       Ionic Polymer Metallic
   Elastomers
                                                             Composite (IPMC)
 • Ferroelectric Polymers

    http://electrochem.cwru.edu/ed/encycl/art-p02-elact-pol.htm




1/4/2011                     ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators
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                                     Definitions
  • Electrostriction - A phenomenon similar to piezoelectricity, but electrostrictive
      ceramics expand according to the square of the voltage whereas piezoelectric materials
      expand linearly. Electrostrictive materials exhibit less hysteresis than piezoelectric
      materials, but are difficult to use at very low voltages. (Ferroelectric EAP)

  • Electroviscosity - The phenomenon of a change in viscosity due to the presence of
      charge on particles suspended in a solvent. (ElectroRheological Fluids)

  • EAP - general term describing polymers that respond to electrical stimulation
  • Electronic EAP - polymer that change shape or dimensions due to migration of
      electrons in response to electric field (usually dry)

  • Ionic EAP         - polymer that change shape or dimensions due to migration of ions in
      response to electric field (usually wet and contains electrolyte)

            http://electrochem.cwru.edu/ed/dict.htm


1/4/2011                   ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators
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                                                 Types of EAP
   EAP type                      Advantages                                                       Disadvantages

               Exhibit rapid response (milliseconds)

               Can hold strain under dc activation
                                                                  Requires high voltages (~100 mV/meter). Recent development allowed
  Electronic                                                           for (~20 mV/meter) in the Ferroelectric EAP
               Induces relatively large actuation forces
       EAP
                                                                  Independent of the voltage polarity, it produces mostly monopolar
               Exhibits high mechanical energy density
                                                                       actuation due to associated electrostriction effect.
               Can operate for a long time in room conditions
                                                                  Requires using an electrolyte

                                                                  Require encapsulation or protective layer in order to operate in open air
                                                                       conditions
               Natural bi-directional actuation that depends on
                    the voltage polarity.                         Low electromechanical coupling efficiency
  Ionic EAP
               Requires low voltage                               Except for CPs and NTs, ionic EAPs do not hold strain under dc voltage

               Some ionic EAP like conducting polymers            Slow response (fraction of a second)
                   have a unique capability of bi-stability
                                                                  Bending EAPs induce a relatively low actuation force

                                                                  Electrolysis occurs in aqueous systems at >1.23 V

                   http://electrochem.cwru.edu/ed/encycl/art-p02-elact-pol.htm
1/4/2011                              ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators
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                                Electronic EAP
  • Passive Dielectric
           – Flexible conductors are used as
             electrodes, separated by a
             passive dielectric polymer.
           – When energized, the electrodes
             attract, squeezing the dielectric
             which stretches and flexes the
             device.
           – Simple and most robust.



                     http://ndeaa.jpl.nasa.gov/ndeaa-pub/IEEE/ElectricFlux.pdf

1/4/2011                    ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators
                                                  Slide-10



                       Electronic EAP (cont.)
  • Ferroelectric
           – Similar to piezoelectric polymers that change crystalline structure
             when energized.
           – Very strong force.
           – High voltage.
  • Graft Isomer
           – Long backbone molecule embeded with electrically responsive
             materials
           – Very high voltages required.
  • Liquid Crystal
           – Crystalline structure liquefies when heated.
           – Strong forces, very elastic. Slow and inefficient.
  • Electrostrictive tape                                                     http://www.unm.edu/~amri/Bigummi.gif

           – Layered films that contract when charged.
                      http://ndeaa.jpl.nasa.gov/ndeaa-pub/IEEE/ElectricFlux.pdf
1/4/2011                     ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators
                                                           Slide-11



                                                Ionic EAP
   • Ionic Polymer Metal Composite (IPMC)
       or

   • Ion Conducting Polymer Films (ICPF)
           – Platinum or gold electrodes are deposited on each side
             of the membrane by the chemical reduction of a metal
             salt dissolved in the swollen membrane.
           – Two films are separated by a polymer electrolyte.
             When oppositely charged, one will expand due to ions
             entering, the other contract. Bends when 1 V is applied
             over the membrane.
           – Can be produced in large sheets from which any form
                                                                            Conducting Polymers
             can be cut.
           – Easy to produce and handle                          http://ndeaa.jpl.nasa.gov/ndeaa-pub/IEEE/ElectricFlux.pdf




1/4/2011                           ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators
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                            Ionic EAP (cont.)
  • Responsive Gels – Cross linked polymers swollen with solvent. They
      change volume by expelling the solvent due to changes like temperature, solvent
      composition, and electric fields.
  • Carbon Nanotubes - Attract ions when electrically charged, decreasing crystal
      structure size by 1% but with great force.
       “Most polymer actuators are nonlinear in their
       response to the applied voltage or current. The
       control of these actuators can be a difficult task.
       Wet and thermal-phase-change actuators are
       typically more difficult to control than dry actuators, since their response to an
       applied voltage or current varies with time. For many applications an absolute
       position control is not a necessity. Polymer actuators are relatively compliant.
       This compliance may be exploited to provide force control, a difficult task with
       other actuator technologies.”
       http://uorganisk.kiku.dk/kurser/kemiidag/polymer_actuators.pdf


1/4/2011                   ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators
                                                Slide-13



                       Sample Configuration
 • Electrostatic actuator MEMS device fabricated on substrate. Layered polymer
   conductor.
 • Replaces chopper wheels on infrared cameras.
 • 100 – 200 V actuation, 5-10 KHz operation. 98% reliability.
 • Applications also include microvalves, electrical switches and variable RF
   capacitors.
 • Array of Artificial Eyelid Actuators (left) and a single Artificial Eyelid Actuator
   (right).




      http://www.mcnc-rdi.org/index.cfm?fuseaction=page&filename=sensors_and_actuators_projects.html
1/4/2011                     ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators
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                 Difficulties (representative)
     • 2000 - Space mission – MUSES lens wiper. (IPMC)
           http://eis.jpl.nasa.gov/ndeaa/nasa-nde/lommas/IPMC-challenges.pdf




1/4/2011                      ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators
                                Slide-15



                 Specifications




1/4/2011   ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators
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                             Comparisons




           http://uorganisk.kiku.dk/kurser/kemiidag/polymer_actuators.pdf

1/4/2011              ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators
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            Limitations and Outlook
  • Moderately new technology. Not very many commercial
    products, although the promise is there.
  • Strength and durability are still a problem.
  • Limited applications – need to find a niche market. A
    few applications already have success. Miniature and
    micro actuators show most promise.
  • Past 5 years have seen significant growth and research
    participation. More expected.
  • Currently almost all EAP materials are made in-house.
    Industry has not regulated does not produce salable
    product.
  • No center for documentation or resources -- currently
    improving
1/4/2011        ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators
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    EAP material and product manufacturers
  http://ndeaa.jpl.nasa.gov/nasa-nde/lommas/eap/EAP-material-n-products.htm
  • Artificial Muscle Incorporated
           – EAP devices including valve controllers, pumps, electric servo
             motor replacement, force and pressure sensors, acoustic
             speakers, and linear position actuators.
             http://www.artificialmuscle.com/
           – Development kits $800-$4000
  • EAMEX Corporation
           – Designed and built a catheter and swimming fish.
             http://www.eamex.co.jp/index_e.html
  • Environmental Robots Inc.
           – Books and presentations for sale. Starter kit “gifts” $50 - $400
           – http://www.environmental-robots.com/Products.htm
1/4/2011                 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators
                                                Slide-19



                                          Models
  An excellent mathematical analysis of IPMC :

  “Ionic polymer–metal composites: III. Modeling and simulation as biomimetic sensors,
  actuators, transducers, and artificial muscles” by Mohsen Shahinpoor and Kwang J Kim.
  www.unm.edu/~amri/SMSReview-3.pdf

  They found velocity to be a function of Bessel Functions,




   Force is influenced by ion flow, electric field, dimensions, uniformity, materials,
   temperature, just to name a few.
1/4/2011                   ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators
                                                                            Slide-20


                                       EAP Fabrication Recipes
  Instructions to make your own EAP! http://ndeaa.jpl.nasa.gov/nasa-nde/lommas/eap/EAP-recipe.htm


  •    Ionic EAP
           – How to make Ion-exchange Polymer Metal matrix Composite (IPMC) - Contribution of Dr.
             Keisuke Oguro, ONRI, Japan
           – How to make triple layer made of Polypyrrole and Solid Polymer Electrolyte -
             Contribution of Dr. José-María Sansiñena and Dr. Virginia Olazábal, JPL's NDEAA
             Technologies Group.
           – How to make Freeform Fabrication of Polyacrylamide and Polyacrylic acid cross-linked
             gels - Contribution of Prof. Paul Calvert, University of Arizona
           – How to make Carbon Nanotube - EAP - contribution of Giovanni Vozzi, University of Pisa,
             Italy
  •    Electronic EAP
           – Electroding Material: For electrodes you can use conductive carbon grease which can be
             available from M.G. Chemicals
           – Polymer Material: An acrylic adhesive tape from 3M (VHB-4910). The thickness should be
             uniform and as thin as possible. The required voltage is ~100 to 200 - Volt/micron.

       Caution: Special attention to safety issues is required when making EAP materials as described in this website, and these issues are not the subject of this
       website. Particularly when making the ionic EAP materials, special safety measures need to be taken and there is a need for advanced expertise and extensive
       experience in chemistry. Also, caution needs to be taken when using high voltage to activate the Electronic EAP materials.




1/4/2011                                   ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

				
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