(reconfigured) final iteration 333t

7/21/2019 (Reconfigured) Final Iteration 333T

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Christian Phan

Hamza Usman

Zachary Murray

The Implementation of Tactile Sensation in

Neural Prosthetics to Provide Sensory Feedac! and Improve Motor Control

"M# $$$T% M&F '(pm )ecture* Friday ' pm &or!shop

The University of Te+as at ,ustin

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Tale of Contents

' #+ecutive Summary00000000000000000011100000000$

( The Implementation of Tactile Sensation in Neural Prosthetics to Provide Sensory

Feedac! and Improve Motor Control00000000001001000000112

2.1 Introduction…………………………………………………………………………...…...4

2.1.1 Statement of Problem…………….…………………………………...…………….……..4

2.2 Proposed Solution………………..………………………………………...………….…..5

2.2.1 Current and Advancing State of the Art…………..………………………...…………….5

2.2.2 Sensor Prosthetics !sing "actile Sensors……...……………………………...…….…...5

2.2.2.1 #escription…………..…………………………………………………………...………..5

2.2.2.2 Application…………………..…………………………………………………...………..$

2.2.2.% &imitations…………………………..…………………………………………...………..$

2.2.2.4 'thical Implications……………………….......………………………………....………..$

2.% Conclusion………………………………………………………………………...………$

$ 3eferences0110000000000000010000000000001110014

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' #+ecutive Summary

Providing tactile feedbac( in neuroprosthetics is the ne)t ma*or step in the development of true+

to+life prosthetic limbs. "his feedbac( ,ould not onl return the user-s lost sense of touch but

,ould enhance the user-s de)terit and intuition ,hen operating the device. /iven sensation of

touch the user-s brain is able to better adapt to the snthetic limb and *udge ,here something is

or ho, hard to grip 0 s(ills that ta(e months to develop ,ithout haptic feedbac(. using

biologicall integrated materials that can sense tactile pressure current neuroprosthetics can

provide the user ,ith sensations of touch vastl improving their ualit of life.

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( The Implementation of Tactile Sensation in Neural Prosthetics to Provide Sensory

Feedac! and Improve Motor Control

(1' Introduction

3ne of the most detrimental and traumatic e)periences a person can have is the loss of a

limb resulting in disabilit and an e)tensive period of rehabilitation ad*usting to a prosthetic.

According to a stud published in 2 b #octor 6athrn 7iegler+/raham 1 in 18 Americans

currentl lives ,ith the loss of a limb and this number ma double b 25.91: ;or people ,ho

have lost a limb even the simplest of tas(s becomes arduous. As a result prosthetics have been

implemented but the ones in circulation toda offer no,here near the de)terit of a human hand.

"his is due to the fact that the don-t allo, the user to accuratel feel ,hat the-re doing. "his

paper presents a possible solution that allo,s the user to receive haptic feedbac( from the

prosthetic far more sensitivel than an current methods.

(1'1' Statement of Prolem

Currentl most prosthetics do not allo, for patients to receive an tactile response. In

other ,ords patients in use of prosthetics can-t phsicall feel anthing through their artificial

limbs. "his ma seem trivial but it-s an intuitive part of the living sstem that is a limb. <ithout

the sensation of touch it becomes e)ceedingl difficult to *udge ho, firm to grip an ob*ect. It

also ta(es a completel different thought to process the mechanical operation of the prosthetic

,hich is cumbersome and unintuitive. =odern prosthetics simpl mimic the mechanical motion

of the missing limb and some don-t even have functionalit serving onl to mimic the loo( of an

arm or a hand. 3nl recentl have there been prosthetics that enable users to full control the

limb>s? through purel neural means but the can also ta(e nearl 2 ears for patients to learn to

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use adeptl.92: @o,ever ,ith the abilit to feel ,hat the-re touching all of these problems

,ould diminish for the patient.

(1( Proposed Solution

(1(1' Current and ,dvancin5 State of the ,rt

<hile recent advancements in the field of prosthetics have attempted to solve the

inadeuac of current prosthetics none have found the ideal solution. #r. "odd 6ui(en et al.

describes in his paper "argeted reinnervation for enhanced prosthetic arm function in a ,oman

,ith a pro)imal amputationB an attempt to add sensor functionalit to prosthetics. "his process

involves a surgical method called "argeted Sensor einnervation >"S?. #uring "S the

residual nerves from an amputated limb are transferred

onto alternative muscle groups that are not

biomechanicall functional since the are no longer

attached to the missing arm.9%: In this procedure the

residual nerves left over from the amputation of a

patient-s arm are se,n into the muscles of their chest.

<hen the patient thin(s of fle)ing their elbo, hand or

fingers the nerves cause the respective muscles in her

chest to fle) instead. "he resulting contraction is then

uantified b an '=/ and used to control the

prosthetic as depicted to the right.9%:

"his ma(es the use of the prosthetic more natural as the user onl has to thin( of ,hat the ,ant

to do and the correct response from the prosthetic occurs.94:

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<hen the e)amined this abilit for the nerves to activate different muscle groups the

found that not onl could the reinnervated tissue

be used to control a prostheticD it could feel

again. "he nerves had regenerated so ,hen

pressure ,as applied to the reinnervated muscles

in certain areas on the chest >sho,n in the image

to the right? the patient felt that pressure ,as

being applied to the fingers of her missing limb.

einnervation can be purposefull implemented to provide a discrete sensation of touch

in the missing limb.95: @o,ever even though this method brings bac( a sense of touch it

doesn-t provide a sensitive enough gradient to let the patient discern bet,een ob*ects.

(1(1( Sensory Prosthetics Usin5 Tactile Sensors

(1(1(1' 6escription

Sensor prosthetics devices ,ith the tactile sensors ,ould allo, the user to actuall feel

,hat the are touching through the artificial limb. Implementing the sensation of touch vastl

improves the functionalit of the device since the user can phsicall feel ,hat the-re

doing. Eudging pressure and feeling response from a prosthetic are integral parts of this solution.

Since grasping and manipulating ob*ects based on ho, the feel is a regular process for the

brain patients can adapt to sensor prosthetics much more easil because the prosthetics provide

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a feel that is natural and familiar ,hile previous prosthetics feel unnatural and involve a lot of

guess,or( using visual clues. 9F:

3ne model designed b #r. Gicholas

<ettel from the !niversit of Southern

California is the iomimetic "actile Sensor

Arra.9: "his device is designed to be an

ine)pensive solution to enhancing the

performance on prosthetic hands in

unstructured environments. <hile current

prosthetic hands are good for specific

situations the lac( of tactile feedbac( ma(es

gripping irregular ob*ects difficult or

impossible. "his sensor arra tac(les the issue

b mimic(ing the mechanical properties and

distributed touch receptors of human fingers.

Similar to a human finger the device has a rigid core surrounded b a deformable shell.

"he shell is composed of a ,ea(l conductive fluid contained ,ithin an elastomeric s(in. "he

core has man electrodes attached to it. "hese electrodes measure the impedance changes ,ithin

the fluid around them. ')ternal forces deform the fluid path resulting in impedance changes that

the electrodes detect. "he inside of the core houses the electrical circuitr necessar to read the

signal and convert it into electrical signal.

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"his device has man applications. It can be used in robotics to allo, autonomous

movement and detailed feedbac( for a robot to ma(e informed decisions an automated

prosthetic ,ith programmed refle)es for specific stimuli or in our case electrical signals directl

fed to nerves to produce haptic feedbac( to allo, a patient to feel ,hat the are touching.

(1(1(1( ,pplication

Several schools including Stanford !niversit and Eohns @op(ins !niversit have

succeeded in producing artificial s(in+li(e materials that can transduce tactical sensations into

electrical signals ,hich then can be transmitted to the brain as the ,ould in human s(in.98: "his

means that the ver act of transmitting an e)ternal stimulus into a biocompatible reading has

been made possible. In the case of the aforementioned "S surger the patient claimed that her

e)perimental sensor prosthetic ,as much easier and more natural to use stating that 9her:

original prosthesis ,asnHt ,orth ,earingthis one is.B9%:

"he iomimetic "actile Sensor Arra has a variet of factors that affect its sensitivit.

"he entire device functions based on the impedance of the current as ,ell as the fluid flo,. "he

fluid flo, is affected b ho, thic( the s(in laer is and ho, easil it is deformed b an stimuli.

"he graph analJes the impedance based on different thic(nesses and grittiness of s(in used for

the outer laer.9: If the s(in is ver thin ,ith no te)ture the membrane is hpersensitive to

small changes in force. As the normal force increases the impedance rapidl diverges until it is

not measurable. @o,ever ,ith a thic(er s(in and higher grit te)ture the impedance increases

predictabl ,hich allo,s a plotting of force vs. impedance. "his can be used to sense touch at

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about .5G to 1G the phsiological force range ideal for a sensor prosthetic. ased upon

different tpes of force >i.e shear normal

diagonal etc? the patterns of impedance

change in a consistent manner. An analsis of

these impedance patterns ields a prosthetic

that can differentiate bet,een the shape of the

ob*ect and possible slipping.

"his is a huge improvement over "S >"argeted Sensor einnervation? as "S cannot

sense ualities of forcesK it is binar. "S can onl detect ,hether a force is present ,ith limited

information about strength and provide binar feedbac( to the user ,hile this sensor arra can

detect direction and strength ,ith accurac.9%: "he components of this device themselves are

ver eas to manufacture and the materials are euall ine)pensive. @o,ever future use of this

prosthetic ,ould reuire surger to connect it either directl to nerves or integrate an electric

stimulator able to transmit signal to neurons.

(1(1(1$ )imitations

"he iomimetic "actile Sensor Arra b itself is an ine)pensive solution but associated

costs of surger implementation into a ,or(ing prosthetic and scaling up ,ould uic(l increase

the cost. "he creation of sensor prosthetics ma have been proven possible but the cost of

producing these devices still drasticall limits their ,idespread use in societ. =aterials that

allo, for biologicall+integrated sensations are still in earl development ,hich means that

the-re designed to ,or( effectivel but not et designed to be cost effective. "he fe, devices

that have succeeded in using such materials to provide feedbac( sensations are hardl affordable.

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A single moelectric prosthetic arm can cost around L1 at the !niversit of California San

;rancisco =edical Center.91:911: Got to mention the cost of surger to even attach a device that

integrates e)ternal data ,ith the bod-s o,n electrical net,or(. All of these barriers lead to a

high cost for the use of sensor prosthetics. ecause of their immense costs sensor prosthetics

are not readil available to the public. !ntil the cost of these ne, prosthetics decrease the ,ill

not be a viable solution to the ma*orit of amputees in the ,orld.

(1(1(12 #thical Implications

A ma*or issue concerning ethical controvers is the use of animal research in the stud of

both sensor feedbac( and locomotive response. efore such related technologies can be applied

to human clinical trials the must first be e)plored and observed in research model animals.

=an activists ob*ect to sub*ecting these beings to contained lives and abnormal bodil

modifications. Animals of distinct intelligence are mainl the topic of such concerns. In the

specific research done related to sensor neuroprosthetics cats and mon(es have been sub*ected

to tests that reuire invasive observation i.e. surger in order to obtain neural net,or(ing data.

912: 91%: Protocols do ho,ever e)ist to maintain the safet and painless accrual of data from

these animals e.g. anesthesia.91%:

(1$ Conclusion

Prosthetics ,ere originall intended to be a replacement of a lost limb. @o,ever no

prosthetic to date has ever come close to full replacing it. All ,e can hope to accomplish is to

mimic or design a prosthetic that can come close to the real thing. In recent ears design choices

have favored moving to,ards allo,ing the prosthetic to function ,ithout sensor feedbac( to the

user ,hich ta(es a,a the human element and moves further from ,hat prosthetics ,ere

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originall intended to doK act as a replacement of an actual limb. "he integral part of a limb is its

abilit to feel. "he limb-s movements no matter ho, minute are onl effective ,hen the user

can feel those movements and ad*ust accordingl ,ithout guess,or(. "he addition of tactile

sensors to prosthetics ,ill ensure that the human element of the lost limb remains intact

improving the ualit of life of the patient and ensuring greater satisfaction.

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$ 3eferences

91: 6. 7iegler+/raham '. E. =ac6enJie P. &. 'phraim ". /. "ravison and . roo(meer

'stimating the Prevalence of &imb &oss in the !nited StatesK 25 to 25B Arch. Phys. Med. Rehabil. vol. 8 no. % pp. 4220428 =ar. 2.

92: S. <atve /. #odd . =ac#onald and '. . Stoppard !pper limb prosthetic

rehabilitationB Orthop. Trauma vol. 25 no. 2 pp. 1%50142 Apr. 211.

9%: ". A. 6ui(en &. A. =iller . #. &ipschutJ . A. &oc( 6. Stubblefield P. #. =arasco

P. 7hou and /. A. #umanian "argeted reinnervation for enhanced prosthetic arm function in a

,oman ,ith a pro)imal amputationK a case studB The Lancet vol. %$8 no. 8558 pp. %F10%

;eb. 2F.

94: I. Iturrate . Chavarriaga &. =ontesano E. =ingueJ and E. del . =illMn "eaching brain+machine interfaces as an alternative paradigm to neuroprosthetics controlB Sci. Rep. vol.

5 p. 1%8% Sep. 215.

95: =. ;. Casanova Canonical circuits of the cerebral corte) as enablers of

neuroprostheticsB Front. Syst. Neurosci. vol. F Gov. 21%.

9$: . 6,o( GeuroprostheticsK 3nce more ,ith feelingB Nature vol. 48F no. F44 pp.

1F$01F =a 21%.

9F: G. <ettels N. E. Santos . S. Eohansson and /. '. &oeb iomimetic "actile Sensor

ArraB Adv. Robot. vol. 22 no. pp. 28048 Ean. 2.

9: Artificiall intelligent snthetic s(in interacts ,ith brain cells.B Healthinnovations. .

98: #. 6. lough S. @ubbard &. N. =c;arland #. /. . Smith E. =. /ambel and /. '.

eiber Prosthetic cost pro*ections for servicemembers ,ith ma*or limb loss from Nietnam and

3I;O3';B . Rehabil. Res. !ev. vol. 4F no. 4 p. %F 21.

91: /. =c/impse and ". C. radford Limb Prosthetics Services and !evices. /aithersburg

=#K Gational Institute of Science and "echnolog 2.

911: =. C. #adarlat E. '. 3-#ohert and P. G. Sabes A learning+based approach to artificialsensor feedbac( leads to optimal integrationB Nat Neurosci vol. 1 no. 1 pp. 1%0144 Ean.

215.

912: 6. A. =aJure( . E. @olins(i #. /. 'veraert . . Stein . 'tienne+Cummings and N.

6. =ushah,ar ;eed for,ard and feedbac( control for over+ground locomotion in anaesthetiJed

catsB . Neural "n#. vol. 8 no. 2 p. 2$% Apr. 212.

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