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Electroactive polymer actuator online database Shkuratoff, K. A.; Genereux, N.; Madden, John D.; Filipozzi, Luca; Hsu, G.; Poon, D.; Van Der Star, A.; Cheng, P.; Irwin, D. 2007

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Invited Paper  Electroactive Polymer Actuator Online Database J.D. Madden*, N. Genereux, K.A. Shkuratoff, A. van der Star, D. Poon, D. Irwin, P.Cheng, G. Hsu, L. Filipozzi. a Department of Electrical & Computer Engineering, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada ABSTRACT As polymer actuator performance improves there is an increasing demand to understand and compare properties. Past comparisons have relied on general statements of properties but do not capture the interdependence of these properties or keep up with the rapid pace of change. Modeling such interdependencies is complex. An alternative is to compile many measurements. A new actuator database has been created that is a compilation of experimental methods and results (mechanical, electrical, chemical and other properties) combined with a web interface. The objective is to capture actuator performance under a wide variety of conditions. The current content of the page is presented and justified. Researchers may submit data to the web page via an online form. Keywords: EAP, conducting polymers, dielectric elastomers, ferroelectric polymers, IPMC, ionomeric polymer metal composites, carbon nanotubes, review, comparison, properties.  1. INTRODUCTION How does a designer decide if a particular actuator is appropriate for their task? How can a researcher decide what properties need to be improved, or compare their materials performance with that of others? This task is particularly challenging for electroactive polymers since they are emerging materials. The database described here and found at actuatorweb.org should help this process by presenting numbers extracted from measurements. So far results from more than 100 experiments on conducting polymer, carbon nanotube and dielectric elastomer actuators have been entered. The conditions under which each of the experiments performed in each paper were performed have been entered into the database.  2. DATABASE INTERFACE DESCRIPTION When accessing actuatorweb.org the title page provides 6 primary options on the left hand column, as shown in Figure 1: ACTUATOR SUMMARY, ACTUATOR SELECTION, ACTUATOR COMPARISON, DATABASE BROWSER, FIELD OVERVIEW and DATA SUBMISSION. Actuator selection is meant to help designers choose a material that suits their needs, while the comparisons section allows ready extraction of trends and developments in the field of electroactive polymers. All categories are now described. 2.1 ACTUATOR SUMMARY ACTUATOR SUMMARY is a static table that provides information as well as pros and cons for each actuator technology listed. Currently this table dates back to 20041 and so does not mention recent advances, such a increased strain in conducting polymers and operation without leakage current in ionic polymer metal composites. However it does provide general information that is useful in comparing actuator types and in making a pre-selection of actuator types for specific applications. 2.2 ACTUATOR SELECTION ACTUATOR SELECTION enables device designers to enter the approximate dimensions, force, displacement, time, cycle life, energy source and acceptable voltage range, in text boxes, shown in Figure 1. A number of properties are then *jmadden at ece.ubc.ca; mm.ece.ubc.ca or actuatorweb.org .  Electroactive Polymer Actuators and Devices (EAPAD) 2007, edited by Yoseph Bar-Cohen, Proc. of SPIE Vol. 6524, 65240P, (2007) · 0277-786X/07/$18 · doi: 10.1117/12.718042  Proc. of SPIE Vol. 6524 65240P-1 Downloaded from SPIE Digital Library on 30 May 2011 to Terms of Use: http://spiedl.org/terms  calculated, including the volume, power and work density. Selecting “Find Actuators” helps guide which actuators are able to provide the work needed within the specified volume, and which ones can use multiple strokes in order to achieve the work. The page also provides some idea of how much mechanical amplification will be needed. For example if the strain of a carbon nanotube actuator is only 0.5 %, the device length is 10 mm and the needed displacement is 1 mm, the displacement produced by a carbon nanotube actuator placed along the length is only 0.05 mm and needs to be amplified by a factor of 20 to provide the needed displacement. This can be done using levers and other mechanisms, but does require additional engineering and expense. The methods used to compute the effectiveness of an actuator are the same as those used in the web page mm.ece.ubc.ca/actuator, and described in the 2005 proceedings of this conference. The main difference is that the old web page has a single value of strain, stress and other properties for each class of actuator, rather than linking the response that has been achieved to measurement conditions. THE IEHEIVEROITYOF ERITISHCOLIJMEIA  Department of  Electrical  EIEwo)000NrS) DIRECTORIES) SEARCH CEO I  Computer  ACTUATOR SELECTION TOOL  • Ero'neer'ng  ACTUATOR SELECTION  - _III1  LEHHAOh (WW)*  Width (WW)*  ThjHkTE(WW)0 I/HI HE (THea)  ACERAEET- WETIE  MEAT FHTHE (H)0  0.f  H iEPIAHE MEet (ee)E  H  WHthfrHJ) WHThDETEiOH (hi/c3)  20000  dEAl StaiR )DiEPIAHEWETO /LETAOH) 0.2  —  AWHAOiHTFTESHHETHH (Ho)0  0.1  Ti ME I/HR otARt (C)  (1.0010067401 302ff 3 J FAT) HEROICS )ht/FH3)0  OCtET I/HAt (FeW)  HL_  pHOETDETEiOH )hW/FH3)  (0.026  _I1  FAT) SpEHi His ETETAS (Mi/hg)0  SCATHE SpEHi His OCtET )W/hg)0  H _____________________  1000  FiTd AHTUTTHTH  Fig. 1. The actuator selection tool input screen. Users input specifications into the white boxes. Selecting “Find Actuators” will result in the page shown in Figure 2. The left hand column is a list of the tools and features available on actuatorweb.org.  The actuator selection tool also estimates how much battery is needed in order to drive the actuator over the selected number of cycles. The battery or power source can end up being much larger than the actuator itself when operation over many cycles is required. A key point to remember for all the comparisons is that stored numbers such as work density and power to mass are normalized by the actuator dimensions only, and do not include packaging, electrolyte, separators, pre-straining mechanisms, connectors and other items whose size does not necessarily scale linearly in proportion to work or force output. For this reason, when selecting actuator technologies it is advisable to chose those that easily meet the work and power requirements. Figure 1 shows some example input parameters that might be appropriate for the development of an artificial urinary sphincter, and Figure 2 shows the resulting output. From Figure 2 it is clear that nearly all of the actuators shown are able to do the work required and meet the power specifications despite the volume constraints. Selection may then be performed based on other properties. For example some of the actuators require extremely large mechanical amplification due to their small strain. This adds an extra challenge to the design. At present the cycle life and voltage constraints set by the user do not prevent data that do not meet these requirements from being displayed. The reason for the omission of the cycle life specifications is that there is very little data to date on this property. The voltage constraint will be included on an upcoming upgrade.  Proc. of SPIE Vol. 6524 65240P-2 Downloaded from SPIE Digital Library on 30 May 2011 to Terms of Use: http://spiedl.org/terms  2.3 Actuator Comparison Plots The ACTUATOR COMPARISON section allows users to plot any two of the properties stored in the database. Up to four simultaneous plots can be created. This allows users to explore the database graphically. This exploration shows similarities and differences between types of actuators, and also points out the tradeoffs between different properties. For example in Figure 3 the stresses and strains achieved in conducting polymer actuators are plotted. From this plot it is clear that high stresses can be achieved (62 MPa in this case) and high strains (13 %), but that these properties have not been achieved simultaneously.  NarMlli..d Mark D.n.itu y• Sahanjail AMplifialtian 104  —  Pau.r D.n.itu 101  k _______________________ 0  20  40  60  60  100  lApli120cftti 140  BttyH  flt thStk pCyTh  . 0.00  0.05  0.10  *  10-4  0.15  0.20  0.25  0.30  10—5 10—3  10—2  Fig. 2. The input shown in Figure 1 leads to the output screen shown here. The red hatching indicates the region in which the actuators fail to meet the work density and power density specifications. The top right plot indicates by what factor the work per unit volume of actuator exceeds the minimum value. The top right plot shows which actuators meet the minimum power requirements. The bottom left plot indicates how fast the actuator must cycle if it is to produce the work in one stroke, normalized by the desired actuation frequency. In this case the actuation rate is slow (0.1 Hz) and the allowed volume is quite large, so actuators don’t need to perform a full cycle in the allotted time in order to complete the work, as is evident from the low relative frequency and by the strokes needed which are less than one.  Any data point in the plots can be selected to look at the full data set and the origin. Placing the cursor over any data point leads to the appearance of a descriptor. Clicking on the point produces the database record for that point. Recently the stresses at which conducting polymer actuators have been shown to operate have greatly increased. Selecting the highest stress dot (as seen in Figure 3) produces the database entries shown in Figure 4. A description of the fields is provided in Figure 5. Note that not all the fields need to be filled out and they are not all relevant. An attempt is made to be complete, but where complete details are needed, these can be obtained by selecting the reference at the bottom of the list, which finds the source with the assistance of Google Scholar.  Proc. of SPIE Vol. 6524 65240P-3 Downloaded from SPIE Digital Library on 30 May 2011 to Terms of Use: http://spiedl.org/terms  Typical Strain ye Oparatins Stress 70  -  60  a  50  -  40  -  a  aa  30  a  20  -  10  0 0  2  6  4  6  10  12  14  Typical Strain (2)  Fig. 3. Plot of operating stress versus typical strain for conducting polymers.  Material Properties Mechanism  CP  Material Additive  S .7h% CNT  Density )hg/m'2)  1500  Dielectric Constant Condoctioity (s/cm) Modolos (sPa)  7 lh  Tensile Strength )MPa)  255  strainattreah(%)  4  7.2  Geometry  fiher  Form  Experiment Resnits Work Density )kJ/m'3) Typical Strain)%) D peratin pptress )MPa) Pswer Density )kW/m'3) Power )W/kg) cycles )Minimsm)  0.85 82  1.2  Efficiency )%) Electrschemica Istrain  Len 5th (mm)  width (mm)  coefficient )%/)c/m'2))  Thich ness (mm)  charge (mc) capacitance (F) Eandwidth (Hz) Strain Rate )%/s) stress Rate )MPa/s)  Doter Diameter (mm) Inner Diameter (mm)  Volome)mm' 2) Nomherof Strands Electrode Properties Name of  Electrolyte Properties Solvent Type 1st Solvent 2nd Solvent Salt  AQ H2D  Concentration )M) Ratio (1st: 2nd Solotion)  1  Anion Cation  stress Relas Rate )Actise) )%/cycle) stress Relas Rate )Inactise) (PP/cycle) creep Rate )Actise)  5.1  (PP/cycle)  creep Rate )Inactise) HCI  (PP/cycle)  Peak Power )W/kg) Peak Engineering Strain  2.51  Aserage Strain Rate )%/s) Aserage Stress Rate  S.S1  ClH+  )MPa/s)  S.44  chargeAlolsme )mc/m'2)  Coating Material  or Isotonic Operotiog Cooditioos  isotonic  Type of Cycling Voltage Mi )V)  CV  Voltage Mao. )V) Voltage Difference )V) Pdmary Avis) )%)  S.S  charge! Mass )m c/kg)  capacitanceNslame -S.2  (Se co n d a ry Avis) )%  S.7  )F/m'2)  Electric Field Intensity (V/m)  Snnrce Infnrmutinn Scarce  Asthor  carkon-Nanotake-Reinforce d Polyaniline Fikers for High-Strength Artificial G.M. Spinks, V. Mottaghitalak, M. F .G. Whitten, P .G. Wallace  Con sta nt Load (N  Fregoency (Ho)  325  Ieee  Fig. 4. The list of the properties available in the database, and values from one of the database entries. Explanations of the categories are given in Figure 5  Proc. of SPIE Vol. 6524 65240P-4 Downloaded from SPIE Digital Library on 30 May 2011 to Terms of Use: http://spiedl.org/terms  NSI P_1 Material  And le led Nr). rats at aa, (. b lse.din tfligfly Pss.C.ts The particular active material used (e.g. Silicone or polyp yrrole or Multiwall Carhon  Additive  Additiopal material additive Ic .o. partitles to i ocrease dielettrittopstaptoripfluepte  Deooito lho/m"?l Dielettric 000staot  Coodottivity lv/tml  I propertiesl. Deooito of the attioe material. Relatioe dielettric permittioito. Moot releoaot is dielectric elasto mers, ferroele otric elasto mers aod other dc ttrooit cAps. elettropittopdu ttivity alopo the primary diretti op is mhith turrept flows. Not relevapt for  Modulus lvFal Tepsile Otrepoth (Meal Otraipaterea h 1°/el  Thepormalizedstiffpessof the attive material alop o the primary attuatiop axis. The stress ahove mhith methapita I fail ore tommoply otturs. The relative elopoatiop at mhith themateria I fails.  dielettrits.  Geometry Form  Lepoth ImmI midth ImmI Thith pesslmm I Outer Di ameterlmm I loper Di ameterlmm I Volume 1mm" 31  Numherof vtrapds lcorps/tm I  Fiher, film, tuhe, hila yer or other geometry. Lepoth of the attive material alop o the primary axis of attuatiop.  midth of the attive material. Thith pess of the attive material loot iptludip 0 pathagip o, separators ett .1.  The di ameterof the active material lip thetaseofa fi her or tuhe The ipper di ameter of the active material lip the case ofatuhe The volume of active materials use d. If multiple films, fihers ortuhes are used, hom mapyo ft hem are there? If the active material is moup d, hom tight is the mipdipo?  Electrode Properties Name of Material  mhat material is used to mahe electrical coptact mith the active material?  Electrolyte Properties volvept Type  The type of solves tip mhich iops are dissolved Ic .o. aqueous, orgapic, iopic liquid, gel orso lid  electrolytel. Dst volvept 2pd volvept Salt  The domipapt solvept Ic .o. aqueous, acetopitrile etc .1.  Catiop Coatipg Material Isometric or Isotopic  Ipcaseofamivture, the secop d largest compopept Ic .o. ethyl epe carhopate The chemical pame for the iops added Ic .o. Sodium Chloride or Tetrahutyl ammopium hevafluoro phosphatel. The salt copceptratiop. The relative proportiops of the first apd secopd solvepts. The pH 1w hep aqueous solutiops are use dl. The apiop pame lrepetitiop of salt category ahove The catiop pame lrepetitiop of salt category ahove Metal, dielectric or other material that coats the electrode. Is the testipg dope upder copstapt load lisotopicl, copstapt lepgth lisometricl or other?  Th  nfl. w' ..nt wiSn c.4 a  Copceptratiop IMI Ratio lost: 2pd Solutiop I pH Apiop  Voltage Mm. IV) Voltage Max. IV) Voltage Differente IV)  The lowest voltage used in operating the actuator (e.g. OVor- by)  The maximum voltage applied (Peak tx Peak). The amplitude xf the applie dvoltage. The relative amount h ywhith the attuator is pre-stretthed along the diretti on of attuation. (Primary Avis) 1°/c) vetondary Axis) 1°/el The relative amount h ywhith the attuator is pre-stretthe d perpenditularto the direttion of  axatixn.  Constant Load INI  Magnitude of forte a pplie dwhen operated under fixed (cad ton ditions.  Frenuentv lHzl Experiment Resnits worh Density )hJ/m"3)  Numherofattuahontvtles ncr setond.  Tvpital Otrainld/ol C neratin g otress IMPa)  Power Density )hm/m"3) Continuous Power lw/hg) Cvtles (Minimum)  Bffitientvld/ol Blettrothemita I Otrain Coeffitient lo/o/IC/m.'.3ll C harge (mCI  Capatitante IF) Bandwidth 1Hz) Otrain Rate 1°/c/sI otress Rate )MPa/s) otress Relax Rate (Active) I %/ty tie otress Relax Rate (Inactive)  The amount of worh generated per unit volume of attive materia ((not intludin g nathagin g,  elettrodes, elettrolvte ett.) Thestrain that is tvpitall vohserve d. The load normalized hy thetross-se tti on area. Themethanita I power per unit volume. The average methanital power under tontinuous attuation. The numher of tytles at whith strain (or stress under isometrit ton ditions I drops to half of its The raho ofthe methanital worh outtothe elettdtal energy in. Theamountofstrainohtaine d per unit tharge, per unit volume I primarily for tondu tting polymers.)  The ahsolute amount of tharge transferred. The total tapatitante of the tell. Therateatwhith the attuatorstrain (or stress) drops hy go 0/0 The average strain per un it time. The average stress per un it time. The average rate at whith stress thanges under tonstant load. The peah rate at whith stress drops (under isometrit ton ditions  I %/ty tie I  Creep Rate (Active) lo/o/tytlel Creep Rate (Inactive) lo/o/tytlel Peah Power lw/hg)  The peah rate of tree p during actuation (typitall yunder tonstant load) The maximum rate at whith tree p is o hserved under fixed dc ctrital tonditions (typitally at tonstant load) Themavimumohservedmethanital power  Peah Bngineedng Otrain (°/o( Average Otrain Rate (°/o/s( Average Otress Rate (MPa/s(  Themavimumstrainohserved. The typ ital strain rate.  Therateatwhithstressisthangin g I primaril ytaltulate d for isometrit measurements). The amount of tharge transferred per unit volume of active material. The amount of tharge transferred per unit mass of active material. Capatitante/ovolume (F/m"3( Thetharge divided hy the voltage, normalized h yvolume. Theintens ity of the elect nt field applied (primarily used to destri he actuation in dielectrits Blectrit Field Intensity (V/mI Charge/ovolume (mC/m"3( Charge/Mass(m C/hg)  BnnrEe nnfnrmutinn  Author  Areferente to the puhlitation from whith the data are ohtained or, if unpuhlishe d, the group from whith the data originated. The names of the authors or providers of the data.  Fig. 5. A brief description of the fields used to describe each actuator experiment.  Proc. of SPIE Vol. 6524 65240P-5 Downloaded from SPIE Digital Library on 30 May 2011 to Terms of Use: http://spiedl.org/terms  2.4 The Database Browser The DATABASE BROWSER allows the database to be scanned, and data to be selected by mechanism and material. Mechanism refers to the type of electroactive polymer actuator – for example it can be a conducting polymer (CP), a carbon nanotube actuator (CNT) or a dielectric elastomer (DE). Selection may also be made by material – e.g. the type of silicone, or the particular conducting polymer (polyaniline or polypyrrole for example). In the database browser a list of entries appears which may be sorted by mechanism, material, strain, strain rate, stress, energy density, power density and source. Sorting is currently done in ascending alphabetic or numerical order, as appropriate to the category. Clicking the category multiple times will enable sorting in descending order to be obtained once the next round of upgrades is performed. Figure 6 shows the results of a sort by operating stress, indicating that the highest stresses obtained are from polyaniline fiber-based actuators. This is perhaps not surprising since these fibres have a high degree of polymer chain alignment along their axes. Other properties are easily viewed, revealing that strains are relatively small in these fibres, also as expected given their chain orientation and the common hypothesis that strain is the result of ion insertion between chains. The complete set of fields associated with a given experiment is accessed by selecting the sheet symbol in the far right hand column (producing a listing as in Figure 4). Note that the database is not yet complete. This is evident from the list of high stress actuation results, in which relaxor ferroelectric polymers are completely absent, for example. Michanism  I CP  Matinal  Work Density  Typical Avanca' Opanatina Strain  (k]/m3) (¾)  PCSa  Strain  Stress  (¾/s)  02  Powin  Sound  Density  (MPa) (kW/m3)  Rote  2  01  under dc ctrnchemicul uti A. Muzzn 'di, C. Degt Innncenti, M. Michelucci, 0. Dc Runni  3  5.3  Pnlyuniline  5.5517  Actuutiue prnperti en uf pnlyuniline fibern under dc ctrnchemicul uti A. Muzzn 'di, C. Degt Innnnenti, M. Minhelunni, 0. Dc Runni  CP  Pulsuniline  43  1.3  0.04  3.3  1.4  Pnlyunilineuctuutnrn: Purt 1. PANI(AMPS) in HCI  ill ti ti  P. Smelu, Hf. Lu) P.R. Mutten CP  Pulsuniline  45  1.5  0.01  3.3  0.33  CP  Pulsuniline  25  0.04  0.03  3.4  0.25  CP  Pubs yrrule  35  1  0.01  3.5  0.35  Cunducting Pubymern Plectru menhuninu I Actuuturn und Strum G.M. Spinku, G .G. Hfullune, L. Liu) 0. Zhuu  LI  CP  Pulyuniline  61  0.72  0.03  0.5  0.61  Pulyunilineuctuuturn: Purt 1. PANI(AMPS)  LI  Pulyunilineuctuuturn: Purt 1. PANI(AMPS) in HCI  P. Smelu, Hf. Lu) P.R. Mutten  Pnlyunilineuctuutnrn: Purt 1. PANI(AMPS) J in HCI  P. Smelu, Hf. Lu) P.R. Mutten  in HCI  P. Smelu, Hf. Lu) P.R. Mutten CP  Pulyp yrrule  12.0  0.0  10.6  CP  Pulyp yrrule  11.2  0.7  15.2  0.61  0.02  17  CumpurinunufCundu cting Pulymer Actuuturn Puned un Pulyp yrrule Duped Hfith Pf4(-), Pfb(-), CfSnuS-, und C1u4-  LI  T. Zumu, S. Huru) Hf. Tukunhimu, K.  CumpurinunufCundu cting Pulymer Actuuturn Puned un Pulyp yrrule Duped Hfith Pf4(-), Pfb(-), CfSnuS-, und C1u4T. Zumu, S. Huru) Hf. Tukunhimu, K.  104  CP  Pulyuniline  CP  Pulyp yrrule  12.5  0.5  20.5  CP  Pulyp yrrule  12.4  0.75  22  0.35  0.01  25.3  1.03  Pulyunilineuctuuturn: Purt 1. PANI(AMPS) in HCI  P. Smelu, Hf. Lu) P.R. Mutten  CumpurinunufCundu cting Pulymer Actuuturn Puned un Pulyp yrrule Duped Hfith Pf4(-), Pfb(-), CfSnuS-, und C1u4T. Zumu, S. Huru) Hf. Tukunhimu, K.  CumpurinunufCundu cting Pulymer Actuuturn Puned un Pulyp yrrule Duped Hfith Pf4(-), Pfb(-), CfSnuS-, und C1u4-  LI  T. Zumu, S. Huru) Hf. Tukunhimu, K. CP  Pulyuniline  99  0.55  Pulyunilineuctuuturn: Purt 1. PANI(AMPS) in HCI  LI  P. Smelu, Hf. Lu) P.R. Mutten CP  Pulyuniline  51  0.15  0.01  34  0.51  Pulyuniline  325  0.55  0.01  62  1.2  Pulyunilineuctuuturn: Purt 1. PANI(AMPS) in HCI  CP  P. Smelu, Hf. Lu) P.R. Mutten Curbun-Nunutube-Reinfurne d Pulyuniline Fibern fur High-strength Artifiniu I G.M. Spinku, V. Muttughitulub, M.  Puhrumi-Suniuni, P.3. Hfhitten) 3.3. Hf ullu cc  Fig. 6. Listing of database entries in ascending order of operating stress. Only the bottom of the table is shown.  Proc. of SPIE Vol. 6524 65240P-6 Downloaded from SPIE Digital Library on 30 May 2011 to Terms of Use: http://spiedl.org/terms  2.5 Data Entry Users who have collected data on actuators may enter their own data via an online form. The form has the same fields as the lists shown in Figures 4 and 5. In order to do so a password needs to be obtained from the site administrator. The data is reviewed by the site administrator and may also be sent out to be reviewing by researchers with relevant expertise. Ideally the online submission will be supported by an emailed document submission containing some details of the experimental conditions and plots of the data from which performance has been extracted. This supporting material may be in the form of a journal article, but would ideally be more complete and contain more of the raw data than a journal article typically does.  3. DISCUSSION AND CONCLUSION A number of review articles and books have been written on electroactive polymers1, 2. These provide valuable descriptions of mechanisms and performance. However in the absence of highly complex models relating operating conditions and material properties, it is important to have access to up to date experimental data in order to obtain a true picture of performance. The actuator database presented provides a platform into which this data can be entered. The mechanisms of presenting the data as well as evaluating the inputs have been presented.  REFERENCES  1. Madden, J. D. W., et al., Oceanic Engineering, IEEE Journal of (2004), 29, 706 2. Bar-Cohen, Y., Electroactive polymer (EAP) actuators as artificial muscle. 2nd ed.; SPIE: Bellingham, WA, (2004)  Proc. of SPIE Vol. 6524 65240P-7 Downloaded from SPIE Digital Library on 30 May 2011 to Terms of Use: http://spiedl.org/terms  


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