electroactive polymeric sensors

Medical Engineering & Physics 28 (2006) 568578

Technical note

Electroactive polymeric sensors in hanr mChauoronto,

b o, 4 Tad

ber 20

Abstract

In stark c s of cfeedback co ty, areof current se ymerselectroactive d disadin related ap ive poconducted to demonstrate its potential for prosthetic applications. With linear responses within the operating range typical of hand prostheses,bending angles, and bending rates were accurately measured with 4.4 2.5 and 4.8 3.5% error, respectively, using the IPMC sensors. Withthese comparable error rates to traditional resistive bend sensors and a wide range of sensitivities and responses, electroactive polymers offera promising alternative to more traditional sensory approaches. Their potential role in prosthetics is further heightened by their flexible andformable structure, and their ability to act as both sensors and actuators. 2005 IPE

Keywords: E

1. Introdu

In a woexplorationmaking todevelopmeof successis its compinformationchanging evibration, tsystem enato drop thein a firm haat home.

Corresponfax: +1 416 4

E-mail ad

1350-4533/$doi:10.1016/jM. Published by Elsevier Ltd. All rights reserved.

lectroactive polymers; Ionic polymer metal composites; Prosthetics; Bend sensor; Sensory; Upper limb prostheses; Hand; Biomimetic

ction

rld of unknown, the hand is a key avenue forand manipulation. From our first attempts at tool-the performance of Beethovens concertos, its

nt has hastened us along the evolutionary pathway[1]. Key to the hands functionality and dexteritylex sensory system, which provides the requisite

to bridge our inner neural networks to our ever-nvironment. With receptors honed to pressure,emperature, and spatial positioning, this complexbles us to catch the glass vase as it slips from grasp,hot potato before damage is done and to engagendshake at the office and yet hold a childs hand

ding author. Tel.: +1 416 425 6220x3515;25 1634.dress: [email protected] (T. Chau).

An entourage of technologies is positioned to benefitfrom the realization of engineered sensory systems withcapabilities emulating that of the natural hand, ranging fromremote manipulation in research or space exploration [2], tonon-invasive surgical techniques [3], to creation of virtualenvironments for training simulations [46]. Perhaps first inline, however, is the field of upper limb prosthetics in whichsensory feedback is critical for obtaining adaptive grasp,reflex capabilities, prevention of slip and tactile exploration[716]. Currently, functional limitations and challenges ofunreliable control have motivated over 70% of amputees inthe United States to select hooks for value of their function-ality [17] while 3050% do not use their hand prostheseson a regular basis [18]. One key limitation responsible forthe marginal performance of prostheses in use today is thelack of sensory feedback available to the controller and theuser, hindering the ability to respond in a natural and appro-priate manner in accordance with the external environment[7,8,1922].

see front matter 2005 IPEM. Published by Elsevier Ltd. All rights reserved..medengphy.2005.09.009response of an ionic polymeElaine Biddiss a,b, Tom

a Bloorview Research Institute, 150 Kilgour Road, TInstitute of Biomaterials and Biomedical Engineering, University of Toront

Received 20 April 2005; received in revised form 14 Septem

ontrast to the inspiring functionality of the natural hand, limitationntrol, challenges of mechanical design, and lack of sensory capacinsory systems and the potential of a selection of electroactive polpolymers are reviewed in terms of their relevant advantages an

plications. Empirical analysis of one of the most novel electroactd prostheses: Bendingetal compositea,b,

Ont., Canada M4G 1R8dle Creek Road, Toronto, Ont., Canada M5S 3G8

05; accepted 28 September 2005

urrent upper limb prostheses stemming from marginalwell-established. This paper provides a critical reviewfor sensory applications in hand prostheses. Candidatevantages, together with their current implementation

lymers, ionic polymer metal composites (IPMC), was

E. Biddiss, T. Chau / Medical Engineering & Physics 28 (2006) 568578 569

The purpose of this study is to review the current liter-ature pertaining to sensory systems in prosthetic hands, tocharacterize physical and biomimetic sensory properties of arange of elinvestigateing bendinhand.

2. Sensory

In contrral hand, pforce sensointo the tratect the drithere is noa sense of tis thereforewith morechanges oftance of senreportedlytual enviroadaptive grsuch as preof activitiethe visualral and prodirect sensessary in aprostheticsare of signdrawback.

Recent esory systemthetic handinstance, thprovides aslippage bysensitive to[28]. The Chaps one ofeffect positsors on theand an accwith handhsors to detesensors are

provide tacof a senso[9] which iin an elastoof a sensoring elemenloop contro

of tasks of daily living. The devices designed in each of thesedevelopmental approaches tend to be quite bulky and aesthet-ically unnatural, a recurring challenge beleaguering artificial

rs. Retion ors forelectrure serovidnts [29veralproviferencally,ters, aiezoelimitefixingecondcation

lectro

ith 17ocess

ratedl to ee marr sele5] for36] foionalationact, ative set whition, cn electasurabnge ivaryinge ofmprehdes anroactiv

Ps aing elet the

tive pers,

EAPsapplicrtifici[40] tThe fectroactive polymers (EAPs), and to empiricallythe potential of one candidate EAP for sens-

g angles and rates in the context of a prosthetic

system in prosthetic hands

ast to the wide ranging sensitivity of the natu-rosthetic hands are typically limited to a singler on the thumb and a strain sensor incorporatednsmission system to regulate grasp and to pro-ve mechanism from damage [23,24]. At present,clinically acceptable system available to provideouch in the prosthetic hand [7]. Sensory feedbacklargely limited to that of a visual nature, togethersubtle auditory cues such as the sound of speedthe motor [25]. Evidence indicating the impor-sory feedback is widespread with haptic feedback

enhancing functional performance by 50% in vir-nments [6]. Sensory feedback is fundamental toasp and slip prevention as necessary for tasks,cision grips, which encompass an estimated 60%s of daily life [26]. Although information fromsystem aids in adaptive grasp both in the natu-sthetic hand [27], grip forces in the absence ofory feedback tend to be much higher than nec-ctivities of daily life such as eating [1,19]. In

, where limiting power consumption and effortificant importance, this becomes a considerable

fforts have acknowledged the importance of sen-s and feedback to the functionality of a pros-

leading to various advancements in this field. Fore commercially available Otto Bock SensorHand

n AutoGrasp feature intended to prevent objectregulating grip using feedback from force sensorsshifts in the centre of gravity of grasped objectsyberhand [24], currently in development, is per-the most elaborate sensory endeavours with Hall

ion sensors to determine joint angles, tension sen-flexion activating cables for force measurements,elerometer inside the palm to determine contacteld objects. In addition, flexible onoff touch sen-rmine contact points, and three-dimensional forcedistributed throughout the hand and fingertips to

tile sensation. Another popular approach is the usery glove such as that developed by Mingrino et al.ncorporates vibration and force sensors embeddedmer glove. Along similar lines, is the developmentthumb [21] which employs a matrix of force sens-ts on the thumb to provide information for closedl during a variety of grasp configurations typical

senso

detecsenso

piezoperatand ppone

Seto theare re

Typictiomeand pbeenof afand smuni

3. E

Wfor prgenemodeon thsenso

al. [3ster [traditmentcompsensioutpusump

Aa me

a chawitha ran

A coprovielect

EAboastto metroacpolymsuch,soryand atems[41].cent developments have however realized sensoryn a scale typical of a fingertip with thick-film forcestatic measurements up to 100 N, screen-printed

ic vibration sensors for slip detection, and tem-nsors to warn of potentially damaging extremes,e temperature compensation for the sensory com-].

additional studies are also in progress as relevantsion of sensory feedback in prosthetic designs anded for interested readers [2,8,12,13,15,16,3033].

the most commonly used sensors include poten-ccelerometers, Hall effect sensors, strain gauges,

lectric vibration sensors. Progress in this area hasd firstly by a lack of appropriate sensors and meansthem to commercially available prosthetic handsly, by the ability to set-up a multi-channel com-link for increased control [7].

active polymers as biomimetic sensors

,000 tactile receptors [34] alone and the capacitying the immense quantities of sensory informationthereby, the natural hand has proven a dauntingmulate despite the plethora of sensors currentlyket. For a comprehensive review of sensors andction, the interested reader is referred to Shieh eta general review of traditional sensors and Web-r those specific to biomedical applications. Manyapproaches, however, are not suitable for imple-in a prosthetic hand, which demands a flexible,nd non-intrusive packaging harbouring a highlynsor with fast response and continuously variablele simultaneously addressing issues of power con-ost, and durability [37].roactive polymer (EAP) is a material that exhibitsle response to a given stimuli, most commonly

n shape or voltage potential. A myriad of EAPsg sensitivities and responses exist as a result ofdistinct chemical and thermodynamic structures.ensive book by Bar Cohen on the subject matterexcellent compilation of information regarding

e polymers in general [38].re lightweight, pliable, quiet, and shatterproof,ectromechanical properties that can be tailoredneeds of specific applications. In addition, elec-

olymers offer many of the typical advantages ofsuch as ease of manufacture and formability. Ashave currently been implemented in a host of sen-ations ranging from haptic and neural interfacesal noses [39] to intelligent chemical sensing sys-o measurement of blood pressure and pulse ratesollowing will detail a selected few electroactive

570 E. Biddiss, T. Chau / Medical Engineering & Physics 28 (2006) 568578

Table 1EAP sensors

Sensor Principle of operation Advantages Related applications

Polypyrrolems, fibrl, mechion

PVDF reions

IPMC deformatic respure con

polymers wfor prosthethey have bthe most pr

3.1. Polyp

A subsean emerginmuscles anin the formchange in vport of ionreactions, athe presencmation or echaracterisof the mate

Polypyrenabling chigh thermThese fabriresistivity con stretchof 2 and anventional sfashioned ithe monitoConverselystimuli is apthese glovethe fingers

Based odrawn betwality of thenatural hantion (i.e., a

etectis [45as mu

ily live handfibresting (Rtationtrainsn load

ble fors (band

SA mLR als

withl size,rs incusede appln bothOxido-reduction reactions induce change inmaterial properties, i.e., volume, resistivity

BiocompatibleMultiformable (filReacts to electricachemical stimulat

Piezoelectric effect induces electricalresponse to mechanical deformation and viceversa

Ease of manufactuSensitive to vibrat

Shift of mobile charges induced bydeformation, resulting in a charge imbalance

Sensitive to largeExhibits biomimeSensitive to moistand distribution

ith high potential in terms of sensory provisiontic hands and the current applications in whicheen implemented. Table 1 provides a summary ofevalent EAPs as biomimetic sensors.

yrrole

t of the conductive polymer class, polypyrrole isg candidate in the race towards practical artificiald sensors. It is biocompatible, can be fashionedof films, fibres, tubules, and sheets, and enacts aolume or electrical conductivity due to the trans-s or solvent resulting from oxidation/reductions typical of conductive polymers. It responds ine of an applied electrical field, mechanical defor-ven thermal or chemical stimuli. Material responsetics are highly dependent on the chemical structurerial.role fibres have been incorporated into fabricsonformable, wearable sensor mechanisms withoresistive and piezoelectric coefficients [42,43].

the danglewellof daof throleadapadaping scarbosuitalevelto the

Ctionssmalsenso

beentactiltrol ics are particularly useful as strain gauges as theirhanges markedly when stretched and is dependentdirection [43]. With a comparable gauge factorincreased dynamic range ten times that of con-

train gauges, these conducting fabrics have beennto sensory gloves and have been demonstrated forring of hand movement and positioning [43,44]., when used in actuation mode (i.e., an electricalplied to obtain a physical expansion/contraction),s have been employed for assistive movement offor rehabilitative purposes [42].n this sensory application, a parallel could beeen these conducting fabrics and the function-slowly adapting, type 2 afferents (SAII) of the

d. The SAII afferents contribute to propriocep-sense of spatial positioning and velocity) through

3.2. Polyvi

The stropolyvinylidfor vibratioing from sin the forment its molbehaviour.the thicknecause a decmoleculesphysical foof the poly

PVDF vmented in aStrain gauges and sensing fabricses, tubules, sheets)anical, thermal,

Sensory gloves for: (a) monitoringof hand movement andpositioning; (b) assistivemovement of the fingers forrehabilitative purposes

PVDF vibration and contactsensors in robotics and prostheticsapplications for tactilediscrimination or slip detection

tion bends Tactile sensorsExploratory and newonse

tent, metal content

on of skin strains, which can be related to joint,46] and used to sense position and velocity asscle lengths and generated forces [7]. Activitiesing incur skin strain of 1015% over the back[47]. Conductive fabrics consisting of polypyr-

respond much in the same manner as the rapidlyA) afferents of the hand in terms of temporal

and are not conducive for detecting slowly vary-[48]. Conversely, conductive fabrics composed ofed rubber (CLR) as opposed to polypyrroles arethe detection of steady and slowly varying strainwidth of dc to 8 Hz) and adapt in a manner similarechanoreceptors [44].o exhibits high potential for prosthetic applica-qualities, such as manufacturability, flexibility,and resilience. Conversely, disadvantages of CLRlude hysteresis, creep, and instability. CLR hasin a variety of force and pressure transducers forications, for contact detection, and for grasp con-robotic and prosthetic hands [14,32,48,49].nylidene uoride

ng piezoelectric characteristics of the polymer,ene fluoride (PVDF), have been widely exploitedn and contact transduction in applications rang-

mart structural components to ultrasonics. Oftenof films, PVDF is mechanically drawn to ori-

ecules and polarized to yield strong piezoelectricThus, the application of an electric field acrossss of the film (in the direction of polarization) willrease in thickness due to the reorientation of its

and net polarization. Conversely, application of arce will yield an electrical response at the surfacemer.ibration and contact sensors have been imple-number of robotics and prosthetics applications,


most commonly for tactile discrimination or slip detection[5055]. Tada et al. [52] for example, fabricated a soft fin-gertip for tactile discrimination using PVDF-based sensorsimbedded ian attemptthe skin. Thstimuli witvibratory resensors expsilicon layewith a morthe signal rthe abilitywas demonin order tothe skin. Usthey designchallengesadvantagesdynamic sepolymers w

3.3. Ionic

Ionic ppromise insensors. Cobetween twduce a voltdeformed (is believedof mobiledeformatioformance owater conttogether wimer [57]. Fufacturing,reader is reShahinpoo

Previoustrated promet al. [61] foducer for lobiocompatiments areenvironmenKonyo et aIPMC modmethod of pactuating cIPMCs in asuccessfullpulse rates

The potexpounded

bending transduction. Models detailing the swelling dynam-ics of ionic polymeric gels, the diffusive mechanisms and iontransport involved in polymer bending and actuation, along

expreric fielred to area fo

matematicaer invexplorexhibfor hancted isollowitial of

mpiri

gold-gth, aMexice methe spateria

ontexte of aedictioal of a

Metho

e IPMfromydratined totial fums ofimensts to aof thissarilyhesis.in a sto m

oppossteppee comnglesr is th

, hencangul

ate. Th4 Am

a acqun different silicone rubber layers of the fingertip into mimic the natural cutis and epidermis layers ofe PVDF sensors responded to transient/low strainh the upper situated sensor exhibiting a strongsponse to the stimuli. The deeper situated PVDFerienced a filtered version of the stimuli, as ther acted as a low pass filter, and thereby respondede stable signal. By processing the differences inesponses of the PVDF sensors at different layers,to discriminate between wood and paper texturesstrated. Fujimoto et al. [54] further used PVDFmimic the characteristics of the RA afferents ining these sensors and developed neural networks,ed a system to determine incipient slip. Despitein calibrating sensors based on soft platforms, theof form, ease and flexibility of fabrication, andnsory response are affording these piezoelectricith increasing popularity.

polymeric metal composites

olymer metal composites (IPMC) hold muchthe development of artificial muscles and smartmposed of a thin polymeric material sandwichedo plated metal electrodes, the materials pro-

age on the order of millivolts when mechanicallyi.e., in bending, stretching, and compression). Itthat this voltage potential is generated by a shiftcharges caused by material stresses induced byn, resulting in a charge imbalance [56]. The per-f IPMCs depends on a number of factors includingent and swelling, metal content and distribution,th molecular and physical properties of the poly-or details regarding the chemical structure, man-and modeling of these materials, the interestedferred to a series of review papers compiled by

r and Kim [5860].s developments in IPMC sensors have demon-

ising results in a variety of applications. Ferrarar example, implemented an IPMC pressure trans-ad measurements in the spine. Reduced thickness,bility, and the ability to operate in wet environ-ideal properties of IPMC sensors for biologicalts in which traditional sensors are often lacking.l. [62] proposed a tactile sensor based on fourules used for velocity and directional detection. Aatterning an IPMC film to enable dual sensing and

apabilities was also suggested. A final example ofction was presented by Keshavarzi et al. [63] whoy employed these sensors for blood pressure andmeasurements.ential of IPMCs as sensors has been theoreticallyparticularly in the area of large deformation and

withelectreferthis aIPMCsystefurthand ehavesors

expethe fpoten

4. E

Ain lenNewfor thsis. Tthe mthe cmanc

of prtypic

4.1.

Thbentout hdesigpotenin tersor dresulsors

neces

prostfixedorderTheby aby thing asenso

shaftshafting r15A5a datssions for the deflection of IPMCs in an appliedd have been derived [60]. The interested reader isreview by Shahinpoor and several other studies in

r details [60,64,65]. The practical performance ofrials in this area, however, has yet to be fully andlly characterized [57]. The selection of IPMCs forstigation was motivated by their relatively novel

atory status together with the potential that theyited as sensors thus far. Exploration of IPMC sen-d prostheses where large deformation bending istherefore a logical step and will be detailed in

ng sections where we will demonstrate the highIPMC sensors and ease of implementation.

cal analysis of IPMC sensors

coated IPMC film, 0.3 mm in thickness, 3.4 cmnd 0.7 cm in width (Environmental Robots Inc.,o, USA) was selected as a suitable geometric fit

acarpophalangeal joint of a typical hand prosthe-ecific objective of this study was to characterizel response to quasi-static and dynamic bending inof a prosthetic hand. To this purpose, the perfor-calibrated IPMC sensor was evaluated in termsn errors for a range of bending rates and anglesprosthetic hand.

dology and apparatus

C sample was loaded as a cantilever beam and0 to 90 at varying rates of bend in air with-on. The apparatus employed for this analysis wasemulate, in a controlled environment, the IPMCsnction as a bending sensor in a prosthetic handexpected bending rates, angles, and overall sen-ions and constraints. In this way, specificity ofparticular prosthesis was avoided as ideally, sen-type could be fitted aftermarket and would nothave to be intrinsic to the initial design of theSpecifically, one end of the IPMC sample wastationary clamp fitted with isolated electrodes ineasure the voltage potential across the polymer.ite end was fixed to a rotating platform operatedr motor with a step size of 0.9, and controlledputer via the parallel port in order to vary bend-and rates reliably. The input as measured by theerefore the angle of rotation of the stepper motoreforth referred to as the bending angle, whilst thear velocity is subsequently denoted as the bend-e output voltage was amplified 100 times (Grassplifier System), converted to a digital signal viaisition board (NI 6014, National Instruments) at


Fig. 1. Schemon one end anon the other.signal process

a rate of 107.0. To redfrequenciesfurther usin[66]. Fig. 1

Using thaccumulatethe sensoring the firsestablishedrate (betwe10 and 90the measuring voltagesame rate tand extenstriggered. Tvarying rattation throu

From eainformationfor both bepeak voltagalong withtime physicpolymer wcurves, as

generated tIn order

the IPMCrates varyining from 1

. Gold-gles. Th(A) upoby a p

imilarly

cted dhe mamethoe first,redicminedh therationon curgnal s

e bendatic of experimental set-up. The polymer is mounted rigidlyd anchored to a rotating platform driven by a stepper motor

The polymer response is filtered, amplified, and digitized foring.

00 samples per second and processed in MatLabuce signal noise, low (below 0.01 Hz) and 60 Hz

were filtered. The recorded signal was filteredg a Daubechies 4 wavelet with soft thresholdingprovides a schematic of the experimental set-up.e above-described apparatus, training data wered for sensor calibration. For each training case,signal was monitored for a duration of 90 s. Dur-t 10 s, the resting voltage of the IPMC sensor was

after which the polymer was bent at a constanten 10 and 110 s1) to a specified angle (between

Fig. 2ing anspikelowed(B). Ssign.

prediing tTwoIn thwas pdeterwhiccalibbratithe sito th). The polymer was maintained at this angle untiled potential returned to that of the initial rest-. At that point, the IPMC sensor was bent at theo 0. In this way, motion typical of both flexionion was captured. Data collection was manuallyhe training set consisted of 160 training cases at

es and angles, selected to provide equal represen-ghout the ranges.ch of the signals in the training set, the necessary

could be extracted to build calibration curvesnding rate and angle of bend. Specifically, thee of the signal was measured (point A in Fig. 2),the time required to reach this voltage peak. Thisally corresponded to the duration over which the

as in motion. Using these two values, calibrationpresented in the subsequent results section, wereo predict bending rates and angles.

to test the calibration and the performance ofsensor, a test set numbering 100 samples withg from 25 to 120 s1 and bending angles rang-

0 to 90 was collected. The degree of bend was

ensuing secA final

of the IPMstimuli mdeployed iwhich thesignal fromsubjected torder to evvarying beof the IPMrapidly alte

4.2. Result

The IPMand exhibitcal deflectiresponse fovoltage in tas depictedcoated IPMC voltage response to deflections of varying bend-e initial resting voltage (I) is non-zero followed by a voltagen deflection of the IPMC sensor. This voltage spike is fol-eriod of adaptation and recovery featuring a voltage trough, a negative deflection incurs an identical response of opposite

irectly from the developed calibration curve relat-gnitude of the voltage peak to the angle of bend.ds were employed to calculate the rate of bend.herein referred to as the direct method, the rate

ted simply by dividing the predicted bend angle asby the voltage peak by the measured time over

bend occurred. The second method, dubbed themethod, involved the use of a second set of cali-ves which relate the predicted bending angle andlope in the region of the voltage peak (IA, Fig. 2)ing rate. This relationship will be clarified in the

tion.

experiment was conducted to gauge the responseC material to higher frequency stimuli. Such

ight be realistically experienced by sensorsn the typical cookie crusher control scheme inhand quickly closes in the absence of a control

the user. In this experiment, the polymer waso 90 bends at 1 and 0.5 Hz. Furthermore, inaluate the IPMCs ability to distinguish betweennd angles at higher rates of stimuli, the responseC material was also observed for bend anglesrnating between 90 and 30.

s

C is characterized by a non-zero resting potentials a highly repeatable voltage response to mechani-on. A dynamic bending stimulus triggers a voltagellowed by a gradual return to the initial restinghe absence of dynamic deflection. This response,in Fig. 2, is reminiscent of that of many neurons


Fig. 3. Peak ving rates greacoefficient ofbecomes incre

when subjefollowed brecovery).IPMC respbending rat

4.2.1. BenAn initi

timing of thery periodsbending rathe initial vof bend aption of benlinear relatthe resultingreater than

= 0.0139

At incrdepicted bytionship bepeak becam

The maginfluencedsmall degrstatisticallytrue for laring rates. Tvoltage peaat rates typThus, withtical dasherelatively inapplies.

ig. 4. Peak voltage vs. bending rate for varying degrees of bend.

. Bending ratedening equationlthough the rate of bend was not reflected in the initialge peak, it was effectively captured by the slope of thege sigs I to Avoltagear re

ratess of thalibra. Fig. 6ration).

0.0

e calinsionaoltage vs. bending angle at varying bending rates. For bend-ter than 45 s1, the relationship is linear with a correlation0.996. At lower bending rates, i.e., 10 s1, this relationshipasingly non-linear.

ct to a step input (i.e., a non-zero resting potentialy an initial response succeeded by adaptation andEvidently, there are several distinct features of theonse that could potentially be used to distinguishes and degrees of bend.

ding angledening equational observation indicates that the magnitude ande voltage trough (B) in the adaptation and recov-of the polymer response was not correlated to

te or bending angle. However, the magnitude ofoltage peak (A) was strongly related to the angle

plied and its sign was representative of the direc-d. As depicted in Fig. 3 and defined in (1), a clearionship existed between the angle of bend () andg voltage peak (Vp) at bending rates approximately

45 s1.

Vp + 0.0134 (1)

F

4.2.2A

voltavoltapointpeaka linangleslopethe cbendcalibin (2

Fc =

Thdimeeasingly lower bending rates (i.e., 10 s1 asthe shaded circular markers in Fig. 3), the rela-

tween the angle of bend and the resulting voltagee increasingly non-linear.nitude of the initial voltage peak was not stronglyby the rate of bend. As illustrated in Fig. 4, forees of bend (i.e.,


Fig. 6. Logarithmic relationship between the calibration factor and thedegree of bend.

calibration method, was given by:

c = Vp(Fct) (3)

where Vp isby (2) and

Converswhich is prtion and invthe time of

d = t

4.2.3. PredFigs. 7

between thing anglesThe overalrates and b

Fig. 7. Test erof bend.

Fig. 8. Test errates.

of poweredrespectivelfor bending

mined4.3%te of

al difft anddeviatod (pates iswheree calisuggeredit oprosth

s obseing anr than7, bend to itically greater average errors for bending angles belowthe voltage peak, Fc the calibration factor definedt is the total time of bend.ely, the simpler direct method, the equation foresented in (4), did not require additional calibra-olved only the bend angle as predicted in (1) andbend in order to predict the bending rate (d).

(4)

icted angles and ratesand 8 depict the calculated percentage error

e predicted and actual values for varying bend-and bending rates for a test set of 100 samples.l percentage errors were calculated for bendingending angles within the typical operating ranges

deter5.3 the ratisticdirecdardmething rtime,by thThisthe chand

AbendloweFig.tendestatisrors for predicted bending angles and rates for various degrees

20 (p < 0.angles beloto the reduangles of bpotentialsdeviationsmethod inc30 (p < 0.0ited a markboth casesnote with r

4.2.4. HigFig. 9 pr

material torors for predicted bending angles and rates for various bending

prosthetic hands, namely 4590 s1 and 1090,y. An average error of 4.4 2.5% was calculatedangle predictions. The bending rate predictions asvia the direct method exhibited an average error of. Alternatively, the calibration method predictedbend with an average error of 4.8 3.5%. No sta-erence in average error was observed between thecalibration methods (p = 0.4), however, the stan-ion was statistically smaller using the calibration= 0.03). The direct method for calculating bend-

extremely vulnerable to errors in the measuredas this susceptibility is limited to a certain degreebration process used in the calibration method.sts certain advantages in terms of robustness tof the calibration method for implementation ineses.rved in Fig. 8, the magnitudes and deviations ofgle errors increased significantly for bending rates40 s1 (p = 0.002). Furthermore, as evident inding angle errors and standard deviations alsoncrease for decreasingly small deflections with09) and larger standard deviations for bendingw 30 (p < 0.01). This error may be attributedced signal to noise ratios observed at smallerend which produce smaller changes in voltage

relative to the resting potentials. The standardof bending rate errors as predicted by the directreased significantly for angles of bend less than3), while those of the calibration method exhib-ed increase for angles below 20 (p < 0.04). In

, there were no statistically significant trends ofegards to the average bending rate errors.

h frequency stimulusesents a final example of the response of the IPMChigher frequency stimuli as might be experienced


Fig. 9. IPMCbending stimu

in prostheta 90 bendits responseresponse todegree of bin voltage.nitudes is ocases. Thetherefore cregion. Thecal responsExplanatioAs evidentchange in vdent on theas typical o

5. Discuss

By studcritical infoand reliablsors and dstatic deflenot be detebe obtainedthe sensorchanges inincorporatebend angleby the sensinformationduring thesient outpuare immate

5.1. Practical challenges

contrast to the advantages of form and sensitivityed byenges,al sen

to benment

prosththesend toeratureraturizationld be c

of opesponmoistung in aof mier re

h the pver, thgnituf thesnt. Inte of ber re

ing raarableeptivel (i.e.,IPMCf thensitivespons

mateespon[68].response to (a) 1 Hz, 90 bending stimuli; (b) 0.5 Hz, 90li and (c) an alternating 90 and 30 stimuli.

ic hands. Fig. 9a presents the IPMCs response tocycle at a frequency of 1 Hz, while Fig. 9b depictsto a 0.5 Hz stimulus. Fig. 9c exhibits the polymeralternating bends of 90 and 30. In all cases, the

end is accurately captured by the relative changeInterestingly, a gradual increase in signal mag-bserved at the onset of the stimulus in all threepolymer response to higher frequency stimuli isharacterized by both a transient and a steady statemechanisms responsible for the electromechani-

e of IPMC materials are not yet fully understood.ns regarding such transients remain speculative.from a comparison of Fig. 9a and b, the relativeoltage for a given degree of bend was not depen-stimulus frequency within the range of 0.51 Hzf prosthetic hands.

ion

Inofferchallditiononlyimpleof afromrespotemptempactershourangeThe rtheirsensiorderpolymwhichoweof mation ocontethe rapolymbendcomppriocsmalThener o

of sethe rIPMCage rstudyying the voltage response of the IPMC polymer,rmation regarding the bend rates can be simply

y extracted. IPMC polymers are dynamic sen-o not maintain a constant voltage response forctions. Angles and rates of bend therefore can-rmined by absolute voltage readings, but mustfrom changes in voltage potentials. In parallel,

does not measure the absolute angle of bend, butthe angle of bend. The controller must thereforethe requisite memory, determining the present

based on the change in voltage potential producedor, in addition to the previous angle of bend. Thenecessary to accomplish this is collected entirely

dynamic phase (i.e., IA in Fig. 2), therefore tran-ts typical of the adaptive phase (i.e., AB in Fig. 2)rial.

ated with ton the ma[59,62]. Capractice in

5.2. Filling

A distining sensorsReliable tenot very dusources andsuch as thoused for before limitedare not verand KampIPMC polymers, there are also several additionalwhich are not encountered in the use of more tra-sors. Firstly, IPMC polymers are responsive notd, but also to pressure and stretch. Therefore, theation of such materials in the mechanical designetic hand must ensure that the sensor is isolatedforms of stress. Secondly, IPMC polymers mayvarying temperatures. When activated in air, a

e dependent response was not observed betweenes ranging from 5 to 50 C, however, further char-

of the temperature response of IPMC materialsonducted to ensure reliable operation within theerating temperatures typical of a hand prostheses.se of these materials is also highly dependent onre content, which may complicate calibration. Forir, as presented in the above results, signals on the

llivolts are produced. No discernable change in thesponse was observed over a 3 month period duringolymer was exposed to air. In wet environments,e response of the IPMC sample jumped an order

de to tens of millivolts. The thresholds and resolu-e sensors therefore depend greatly on the moistureaddition, thresholds of detection also depend onend. For example, when activated in air, the IPMCmained insensitive to large angle deformations attes of less than about 0.75 min1 (Note: this is

to the threshold sensitivity of the natural pro-system, i.e., 14 min1 [7]). Conversely, very

1), but rapid deflections, were reliably detected.polymers therefore respond much in the man-

RA afferents innervating the hand, both in termsity to dynamic stimuli and the phasic nature ofe. Lastly, the general characteristic response ofrials has been well-established (i.e., a linear volt-

se to deflection) both in this paper and in previousThe quantitative measures (i.e., the slope associ-he linear relationship), however, depend largelynufacturing techniques and standards employedlibration is therefore a necessary and importantthe use of IPMC sensors.

the void

ct void in the availability of light and reliable bend-for proprioceptive applications currently exists.

chnologies such as strain gauges are typicallyrable, while fibre optics require additional lightadded complexity, and magnetic-based sensors

se utilizing the Hall effect can become bulky whennd detection [69]. Typically, selection is there-to resistance-based bend sensors, many of which

y reliable as determined by a study by Simoneer [69] in which the most promising bend sen-


sor exhibited a highly non-linear response with repeatabilityerrors ranging from 1.9 to 5.4% for a single grip configu-ration. Based on these findings, the linear response of theIPMC sensangle, anda proprioce

5.3. Biologprosthetics

A deepesensory sysdesign of itengineeredthat of theof sciencesensory sysneering desshould be usory receptto their undsensors ran

capture thethetic handpolymers oa range ofFurthermornology [56with impromay furthehand, senspopulationmation beyThis princicreation ofing of arrathe motion[33].

A seconspecificity,ited by thegroups of msible for agiven rangresponse (iLikewise, eficity and rrange of opchallenge tare highlyto overcomopment ofother handresponses pEAP candiand pressu

both the slowly and rapidly adapting afferents innervating thenatural hand. This diversity, in conjunction with the ability totailor the chemical composition of these materials in order to

their se candthirdformaousannts of

ed toonmenying tpropon to try sysof ion

loped. Devl integ a coh sensd [73]

onclu

conc

aterialary adechniqflexibtor ans of dve rubmetalthe fu

ing anveragaturalerrors

s [7].l resishighlyopticshigh

red duthat thhetic ds alsmechulk, emakinacticalr, thefor a

n of dior, its ability to detect bend rate as well as bendits comparable error rates, suggest its promise asptive sensor for prosthetic applications.

ical analogues: EAP potential in hand

r appreciation of the intricacies of the biologicaltem of the hand yields valuable insight as to thes engineering counterpart. Although the day whendevices will paint a sensory picture on par withbiological hand remains for the moment a topicfiction, several permeating features of the naturaltem could and should be incorporated into engi-igns. Firstly, the importance of form to functionnderlined. The location and structure of the sen-

ors in the natural hand are highly variable and keyerlying function [70,71]. In parallel, engineeredging in form and structure are also necessary tovarying functional tasks required by the pros-

, from proprioception to slip control. Electroactiveffer this potential and are easily manufactured informs from fibres, to films, to fabrics or strips.e, the proven potential of EAPs in MEMs tech-] promises an age of highly miniaturized sensorsved resolution and ease of implementation. Thisr encourage the use of sensor arrays. In the naturalory information is often processed in terms of aof receptors in order to extract additional infor-ond that offered by individual receptors [1,70].ple has been adopted in endeavours toward thesensitive skin whereby higher level process-

ys of force sensors lend information regarding, direction, and orientation of stimuli as well

d feature of the natural hand is the concept ofexemplified by the varying filter properties exhib-different sensory receptors [4,70]. Each of the four

echanoreceptors for instance, is largely respon-dominant sensory function and responds within ae of stimuli [70,72]. Additionally, the manner of.e., tonic or phasic) is well-suited to the stimulus.ngineered sensors must also maintain this speci-

espond in a predictable manner within a practicalerating conditions. This may present a degree ofo the use of some varieties of ionic EAPs whichsensitive to moisture content for example. Effortse this limitation are ongoing including the devel-protective coatings that limit dehydration. On the, the diversity of EAPs offers a unique range ofaralleling that of the natural hand. As presented,

dates for detection of bending, strain, vibration,re are available with varying responses mirroring

tuneviabl

Afor inof thamou

formenvirsatisfbeenmatiosenso

siondeveversa

neura

vidinwhicveye

6. C

Inof mpriming ttheiractuastageductiioniclyzedbendics. Athe ntudejointtionaof afibreofferrequiableprostIPMCiliaryadd btem,imprtrollestudynatioensory specificity and response, presents them asidates for engineered sensors in hand prostheses.general feature of the natural hand is its capacitytion integration and processing [1,70]. With tensds of receptors, the natural hand produces vast

sensory information, which is efficiently trans-yield an accurate sensory picture of our externalt. Electroactive polymers hold much promise inhe need for suitable sensors, but they have alsosed as a mode of communicating sensory infor-he user, an important challenge in the design oftems. Electroactive polymers enable the conver-ic signals, typical of the membrane potentials

at the neural level, to electronic signals and viceelopment of electroactive polymers suitable forrfaces is currently underway in the hopes of pro-nnection to the peripheral nervous system throughory information and user response could be con-.

sions

lusion, electroactive polymers are a novel classwhose full potential has yet to be realized. Thevantages of EAPs over more traditional sens-ues for implementation in hand prostheses lie inility, manufacturability, diversity, and dual role asd sensor. The state of technology is at varyingevelopment ranging from well-established con-ber pressure sensors, to the more revolutionarypolymer composites. In this study, we have ana-nctional potential of IPMC sensors for measuringgles and rates in the context of hand prosthet-e IPMC sensor errors were on par with those ofproprioceptive system, for which mean ampli-of 35 are typical in the metacarpophalangealThese errors were also comparable to conven-tance-based bend sensors with the added benefit

linear response. Conventional sensors, such as, strain gauges, and magnetic-based sensors alsoresolution and accuracy, however, without therability, flexibility, and compact size, it is improb-ey will be incorporated into clinically acceptableevices. Contrary to many traditional approaches,

o do not require external power supplies or aux-anisms, such as light or magnetic sources whichnergy requirements, and complexity to the sys-g the incorporation of such sensors aftermarket, if not impossible. In a practical prosthetic con-recommended signal filtering employed in this

n IPMC sensor, could be achieved with a combi-gital processing on a microcontroller platform and


analogue manipulation using small, low power integrated cir-cuits. Their unique attributes and their favourable response asdemonstrated in this study endorse IPMC sensors as a viableand much nback is to bpolymers mthe next gefunctional

Acknowled

This woand EngineResearch C

Reference

[1] Goodwinunderlyi2004;27:

[2] ShimojoR, et al.from a rProceedi& Autom

[3] Eltaib Maccess s

[4] Konyo Mplay forInternati2003. p.

[5] Tzafestation in dPart A:

[6] Richardments: sWorksho

[7] Jones L.Teleoper

[8] Riso RRtactile anTechnol

[9] MingrinoprosthesConf Int

[10] CarrozzaZecca Mhand witInternati2003. p.

[11] Hauglansory feedIn: ProcIEEE En23102.

[12] Pattersonback sysJ Rehab

[13] Sasaki YinterfereSecondp. 2402

[14] Mabuchi K, Suzuki T, Kunimoto M, Shimojo M, Kakuta N, Saito N,et al. A system of interpreting somatic sensations for use with artifi-cial hands and limbs. In: Proceedings of the First Joint BMES/EMBS

onferen. 6434ura A,pmentrosthes6.ecca MC, et

eptiveoboticsang J,vist L.004;39:assa B

f an unutom 2

nmanneedbackhys 20owak D

ontrol i004;127arpaneumb forans Nrembla

elderlith maarrozzaario P

esearch002;7:1arrozzaani F.and intEEE/RSms (IRcott RNng Tecyberd P. The

outhameeks D

thecreasesuchhamrized[Onlin

0Rutschranny Alm forcPhys) 2ofukuand sysyst, Maazeroo

EEE Inokoi Hutual a

004;313tiehl WSensitivonferen0.eeded alternative if proprioceptive sensory feed-e realized in prosthetic applications. Electroactiveay indeed provide the jump-start needed to evolve

neration of prosthetics with promises of increasedand sensory capacity.

gements

rk was supported in part by the Natural Sciencesering Research Council, and in part by the Canadahairs Program.

s

AW, Wheat HE. Sensory signals in neural populationsng tactile perception and manipulation. Annu Rev Neurosci5377.M, Suzuki T, Namikiz A, Saito T, Kunimoto M, MakinoDevelopment of a system for experiencing tactile sensation

obot hand by electrically stimulating sensory nerve fiber. In:ngs of the 2003 IEEE International Conference on Roboticsation Taipei, vol. 1. 2003. p. 126470.EH, Hewit JR. Tactile sensing technology for minimal

urgerya review. Mechatronics 2003;13:116377., Akazawa K, Tadokoro S, Takamori T. Tactile feel dis-

virtual active touch. In: Proceedings of the 2003 IEEE/RSJonal Conference on Intelligent Robots and Systems, vol. 3.374450.

s CS. Whole-hand kinesthetic feedback and haptic percep-extrous virtual manipulation. IEEE Trans Syst Man CybernSyst Hum 2003;33:10013.P, Coiffet P. Human perceptual issues in virtual environ-ensory substitution and information redundancy. IEEE Intp Robot Hum Commun 1995:3016.Dextrous hands: human, prosthetic, and robotic. Presence:

ators Virtual Environ 1997;6:2946.. Strategies for providing upper extremity amputees withd hand position feedbackmoving closer to the bionic arm.Health Care 1999;7:4019.

A, Bucci A, Magni R, Dario P. Slippage control in handes by sensing grasping forces and sliding motion. IEEE Intell Robots Syst 1994;3:18039.

MC, Vecchit E, Sebastianit E, Cappiellot G, Roccellat S,, et al. Experimental analysis of an innovative prosthetich proprioceptive sensors. In: Proceedings of the 2003 IEEEonal Conference on Robotics & Automation Taipei, vol. 2.22305.

d M, Lickel A. Improved method for use of natural sen-back in control of grasp force for stimulated hand muscles.

eedings of the 20th Annual International Conference of thegineering in Medicine and Biology Society, vol. 5. 1998. p.

PE, Katz JA. Design and evaluation of a sensory feed-tem that provides grasping pressure in a myoelectric hand.il Res Dev 1992;29:18., Nakayama Y, Yoshida M. Sensory feedback system usingntial current for EMG prosthetic hand. In: Proceedings of theJoint EMBS/BMES Conference Houston TX, vol. 3. 2002.3.

Cp

[15] To

p2

[16] ZMc

R[17] Y

k2

[18] Mo

A[19] I

fP

[20] Nc

2[21] C

thT

[22] Tinw

[23] CDr

2[24] C

tihIte

[25] SE

[26] KMS

[27] Winin

[28] Ptu42

[29] Cfi(

[30] GhS

[31] KI

[32] YM2

[33] S

C7ce Serving Humanity, Advancing Technology, vol. 1. 1998..Lamberti C, Davalli A, Sacchetti R. Experimental devel-

of a sensory control system for an upper limb myoelectricis with cosmetic covering. J Rehabil Res Dev 1998;35:14

, Cappiello G, Sebastiani F, Roccella S, Vecchi F, Carrozzaal. Experimental analysis of the proprioceptive and extero-sensors of an underactuated prosthetic hand. Adv Rehabil

Lecture Notes Control Inform Sci 2004;306:23342.Pena Pitarch E, Abdel-Malek K, Patrick A, Lind-

A multi-fingered hand prosthesis. Mech Machine Theory55581., Rocella S, Carrozza MC, Dario P. Design and developmentderactuated prosthetic hand. Proc IEEE Int Conf Robotics002;4:33749.A, Haugland M. Functional evaluation of natural sensory

incorporated in a hand grasp neuroprosthesis. Med Eng04;26:43947.

A, Glasauer S, Hermsdorfer J. How predictive is grip forcen the complete absence of somatosensory feedback? Brain(Pt 1):18292.

to J, Micera S, Zaccone F, Vecchi F, Dario P. A sensorizedr force closed-loop control of hand neuroprostheses. IEEE

eural Syst Rehabil Eng 2003;11:34653.y F, Wong K, Sanderson R, Cote L. Tactile spatial acuityy persons: assessment with grating domes and relationshipnual dexterity. Somatosensory Motor Res 2003;20:12732.

MC, Massa B, Micera S, Lazzarini R, Zecca M,. The development of a novel prosthetic handongoingand preliminary results. IEEE/ASME Trans Mechatronics0814.

MC, Dario P, Vecchi F, Roccella S, Zecca M, Sebas-The CyberHand: on the design of a cybernetic prostheticended to be interfaced to the peripheral nervous system. In:J International Conference on Intelligent Robots and Sys-OS 2003), vol. 3. 2003. p. 26427., Parker PA. Myoelectric prostheses: state of the art. J Med

hnol 1998;12:14351.J, Light C, Chappell PH, Nightingale JM, Whatley D, Evans

design of anthropomorphic prosthetic hands: a study of thepton Hand. Robotica 2001;19:593600.L, Wallace SA, Noteboom JT. Precision-grip force changes

anatomical and prosthetic limb during predictable load. Exp Brain Res 2000;132:40410.mer G. The tactile slip sensor: integration of a minia-

sensory device on an myoelectric hand 2004, Decembere] http://www.ottobock.se/info download/pdf/Puchhammer%sensor%20GB.pdf., Cotton DPJ, Chappell PH, Beeby SP, White NM. Thick-

e and slip sensors for a prosthetic hand. Sensors Actuat A005;A123A124:16271.A, Tanaka Y, Tsuboi J. Development of a flexible artificialtem equipped with a slip sensor. JSME Int J Ser C: Mechchine Elements Manuf 2000;43:37886.

ni H, Fairbanks D, Chen A, Shin G. The magic glove. Proct Conf Robotics Autom 2004;1:75763., Arieta AH, Katoh R, Yu W, Watanabe I, Maruishi M.daptation in a prosthetics application. Embodied Artif Intell9:14659.D, Lalla L, Breazeal CA. Somatic Alphabet approach toe Skin. In: Proceedings of the 2004 IEEE Internationalce on Robotics & Automation, vol. 3. 2004. p. 2865


[34] Seow K. Physiology of touch, grip, and gait. In: Webster J, editor.Tactile sensors for robotics and medicine. New York: John Wiley &Sons, Inc.; 1988. p. 1340.

[35] Shieh J, Huber JE, Fleck NE, Ashby MF. The selection of sensors.Mater Sci 2001;46:461504.

[36] Webster J, editor. Tactile sensors for robotics and medicine. NewYork: John Wiley & Sons, Inc.; 1988.

[37] Churchill M. General tactile sensor requirements. In: Webster J, edi-tor. Tactile sensors for robotics and medicine. New York: John Wiley& Sons,

[38] Bar-Cohficial mu

[39] Bar-CohCohen Ymuscles.

[40] Riley PJtive elec

[41] Keshavarate, andites sensInternati36976.

[42] De Rossware. M

[43] Spinks Gelectrom2003;192

[44] Tognettiet al. WProceediEMBS C

[45] Edin BBinformat1995;487

[46] Collins DperceptioPhysiol

[47] CutkoskKluwer

[48] Shimojosensor s

stitched[49] Hussain

pressure[50] Mingrino

prosthesConf Int

[51] Sasaki Kslip andhand. In

[52] Tada Y,faces byIEEE In

[53] Jiang Mhand wi2004;44:

[54] Fujimotoment ofof staticConferenSystems

[55] Dargahi J. A piezoelectric tactile sensor with three sensing elementsfor robotic, endoscopic and prosthetic applications. Sensors ActuatA (Phys) 2000;A80:2330.

[56] Shahinpoor M. Potential applications of electroactive polymer sen-sors and actuators in MEMS technologies. In: Bar-Cohen Y, editor.Proceedings SPIE, Smart Materials, vol. 4234. 2001. p. 20314.

[57] Nemat-Nasser S, Thomas C. Ionomeric polymermetal compos-ites. In: Bar-Cohen Y, editor. Electroactive polymer (EAP) actua-tors as Artificial muscles. Washington: SPIE Press; 2001. p. 139

2.hahinpoentals.wang Kfacturinhahinpoodelin

ucers,8.errara Lel E, epressu

PIE Cool. 366onyo M

ty sensoditor. Plectroa004. p.eshava

ate, andensors.

evices,i H,

ess sim004;19:i H, Yodel d

esponsiPolymaubechomm P

acquesisual fef Toronhahinpoolymernd artifiimone

tor to mohnsonors. Cuirzniekirection001;21:ohnsonechano

ol 2000tero TiomimelectroaaterialInc.; 1988. p. 112.en Y, editor. Electroactive polymer (EAP) actuators as arti-scles. Washington: SPIE Press; 2001.en Y. EAP applications, potential, and challenges. In: Bar-, editor. Electroactive polymer (EAP) actuators as artificialWashington: SPIE Press; 2001. p. 61655.

, Wallace GG. Intelligent chemical systems based on conduc-troactive polymers. J Intell Mater Syst Struct 1991;2:22838.rzi A, Shahinpoor M, Kim KJ, Lantz J. Blood pressure, pulse

rhythm measurement using ionic polymermetal compos-ors. In: Bar-Cohen Y, editor. Proceedings of SPIE - Theonal Society for Optical Engineering, vol. 3669. 1999. p.

i D, Della Santa A, Mazzoldi A. Dressware: wearable hard-ater Sci Eng C 1999;7:315.

M, Wallace GG, Liu L, Zhou D. Conducting polymersechanical actuators and strain sensors. Macromol Symp:1619.A, Carpi F, Lorussi F, Mazzoldi A, Orsini R, Scilingo EP,earable sensory-motor orthoses for tele-rehabilitation. In:ngs of the 25th Annual International Conference of the IEEEancun Mexico September, vol. 4. 2003. p. 37247., Johansson N. Skin strain patterns provide kinaesthetic

ion to the human central nervous system. J Physiol (Lond):24351.F, Refshauge KM, Gandevia SC. Sensory integration in then of movements at the human metacarpophalangeal joint. J

(Lond) 2000;529:50515.y MR. Robotic grasping and fine manipulation. Boston:Academic Publishers; 1985.M, Namiki A, Ishikawa M, Makino R, Mabuchi K. A tactile

heet using pressure conductive rubber with electrical-wiresmethod. IEEE Sen J 2004;4:58996.M, Choa Y, Niihara K. Conductive rubber materials forsensors. J Mater Sci Lett 2001;20:5257.A, Bucci A, Magni R, Dario P. Slippage control in hand

es by sensing grasping forces and sliding motion. IEEE Intell Robots Syst 1994;3:18039., Hirota T, Fujikake Y, Nakaki H. Signal processing for

contact sensing and its application to a two-fingered robotictegr Computer-Aided Eng 2001;8:28391.Hosoda K, Yamasaki Y, Asada M. Sensing the texture of sur-

anthropomorphic soft fingertips with multi-modal sensors.t Conf Intell Robots Syst 2003;1:315., Wang R, Luo Z, Jin D, Zhang J. Myoelectric prostheticth tactile and slip feedback functions. J Tsinghua Univ10513.I, Yamada Y, Morizono T, Umetani Y, Maeno T. Develop-

artificial finger skin to detect incipient slip for realizationfriction sensation. In: Proceedings of IEEE Internationalce on Multisensor Fusion and Integration for Intelligent

. 2003. p. 1520.

9[58] S

m

[59] Ku

[60] SMd8

[61] Fz

a

Sv

[62] Kie

E2

[63] Kr

s

D[64] L

l2

[65] LMr

J[66] D

C[67] J

v

o

[68] Spa

[69] Si

[70] Jt

[71] Bd2

[72] Jm

i[73] O

bEMor M, Kim KJ. Ionic polymermetal composites: I. Funda-Smart Mater Struct 2001;10:81933., Shahinpoor M. Ionic polymermetal composites: II. Man-

g. Smart Mater Struct 2003;12:6579.or M, Kim KJ. Ionic polymermetal composites: III.

g and simulation as biomimetic sensors, actuators, trans-and artificial muscles. Smart Mater Struct 2004;13:1362

, Shahinpoor M, Kim KJ, Schreyer B, Keshavarzi A, Ben-t al. Use of ionic polymermetal composites (IPMCs) asre transducer in the human spine. In: Bar-Cohen Y, editor.nference on Electroactive Polymer Actuators and Devices,

9. 1999. p. 394401., Konishi Y, Tadokoro S, Kishima T. Development of veloc-r using ionic polymermetal composites. In: Bar-Cohen Y,roceedings of SPIE: Smart Structures and Materials 2004:ctive Polymer Actuators and Devices (EAPAD), vol. 5385.30718.

rzi A, Shahinpoor M, Kim KJ, Lantz J. Blood pressure, pulserhythm measurement using ionic polymermetal composites

In: SPIE Conference on Electroactive Polymer Actuators andvol. 3669. 1999. p. 36976.

Chen J, Lam KY. Multiphysical modeling and mesh-ulation of electric-sensitive hydrogels. Biosens Bioelectron1097107.uana Z, Lam KY, Lee HP, Chena J, Hanes J, et al.evelopment and numerical simulation of electric-stimulus-

ve hydrogels subject to an externally applied electric field.Sci - Part B: Polym Phys 2004;42:151431.ies I. Orthonormal bases of compactly supported wavelets.ure Appl Math 1998;41:90996.G. Powered prosthetic hand function: design issues andedback. M.A.Sc. thesis. Dept. of Mech. Eng., Universityto, 1994.or M, Bar-Cohen Y, Simpson JO, Smith J. Ionic

metal composites (IPMCs) as biomimetic sensors, actuatorscial musclesa review. Smart Mater Struct 1998;7:R1530.

LK, Kamper DG. Design considerations for a wearable mon-easure finger posture. J NeuroEng Rehabil 2005;2:5.KO. The roles and functions of cutaneous mechanorecep-

rr Opin Neurobiol 2001;11:45561.I, Jenmalm P, Goodwin AW, Johansson RS. Encoding ofof fingertip forces by human tactile afferents. J Neurosci

822237.KO, Yoshioka T, VegaBermudez F. Tactile functions ofreceptive afferents innervating the hand. J Clin Neurophys-;17:53958.F, Canero I, Villanueva S. EAP as multifunctional andtic materials. In: Bar-Cohen Y, editor. Proceedings of SPIE:ctive Polymer Actuators and Devices, Smart Structures ands, vol. 3669. 1999. p. 2634.

Electroactive polymeric sensors in hand prostheses: Bending response of an ionic polymer metal compositeIntroductionSensory system in prosthetic handsElectroactive polymers as biomimetic sensorsPolypyrrolePolyvinylidene fluorideIonic polymeric metal composites

Empirical analysis of IPMC sensorsMethodology and apparatusResultsBending angle-defining equationBending rate-defining equationPredicted angles and ratesHigh frequency stimulus

DiscussionPractical challengesFilling the voidBiological analogues: EAP potential in hand prosthetics

ConclusionsAcknowledgementsReferences

electroactive polymeric sensors

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