ECE5320 Mechatronics Assignment#01: Literature Survey on Sensors and Actuators Topic: Electroactive Polymers (EAP) or A

1. ECE5320 MechatronicsAssignment#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

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. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

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

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. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

5. 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 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

6. List of the leading EAP materials http://electrochem.cwru.edu/ed/encycl/art-p02-elact-pol.htm ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

7. 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 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

8. Types of EAP http://electrochem.cwru.edu/ed/encycl/art-p02-elact-pol.htm ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

9. 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 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

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 • Layered films that contract when charged. http://www.unm.edu/~amri/Bigummi.gif http://ndeaa.jpl.nasa.gov/ndeaa-pub/IEEE/ElectricFlux.pdf ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

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 can be cut. • Easy to produce and handle Conducting Polymers http://ndeaa.jpl.nasa.gov/ndeaa-pub/IEEE/ElectricFlux.pdf ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

12. 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 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

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 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

14. Difficulties (representative) • 2000 - Space mission – MUSES lens wiper. (IPMC) http://eis.jpl.nasa.gov/ndeaa/nasa-nde/lommas/IPMC-challenges.pdf ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

15. Specifications ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

16. Comparisons http://uorganisk.kiku.dk/kurser/kemiidag/polymer_actuators.pdf ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

17. 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 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

18. 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 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

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. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

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 makeFreeform Fabrication of Polyacrylamide and Polyacrylic acid cross-linked gels - Contribution of Prof. Paul Calvert, University of Arizona • How to makeCarbon 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. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators