An Implanted, Stimulated Muscle Powered Piezoelectric Generator

Beth Lewandowski

NASA Glenn Research Center

A totally implantable piezoelectric generator system able to harness power from

electrically activated muscle could be used to augment the power systems of implanted

medical devices, such as neural prostheses, by reducing the number of battery

replacement surgeries or by allowing periods of untethered functionality. The features of

our generator design are no moving parts and the use of a portion of the generated power

for system operation and regulation. A software model of the system has been developed

and simulations have been performed to predict the output power as the system

parameters were varied within their constraints. Mechanical forces that mimic muscle

forces have been experimentally applied to a piezoelectric generator to verify the

accuracy of the simulations and to explore losses due to mechanical coupling. Depending

on the selection of system parameters, software simulations predict that this generator

concept can generate up to approximately 700 µW of power, which is greater than the

power necessary to drive the generator, conservatively estimated to be 50 μW. These

results suggest that this concept has the potential to be an implantable, self-replenishing

power source and further investigation is underway.

https://ntrs.nasa.gov/search.jsp?R=20070017901 2018-04-18T01:15:19+00:00Z

1

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AN

IMP

LAN

TED

, STI

MU

LATE

D M

US

CLE

P

OW

ER

ED

PIE

ZOE

LEC

TRIC

GE

NE

RA

TOR

UTA

Wor

ksho

p on

Pie

zoel

ectri

c E

nerg

y H

arve

stin

g1/

31/0

7

Bet

h Le

wan

dow

ski

Bio

scie

nce

and

Tech

nolo

gy B

ranc

hN

AS

A G

lenn

Res

earc

h C

ente

r

2

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iona

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CO

LLA

BO

RA

TIV

E P

RO

JEC

T

The

Cle

vela

nd F

unct

iona

l Ele

ctric

al

Stim

ulat

ion

(FE

S) C

ente

r is

dedi

cate

d to

th

e ad

vanc

emen

t of n

euro

-aug

men

tatio

n an

d ne

uro-

pros

thet

ic s

olut

ions

.

Cas

e W

este

rn

Res

erve

Uni

vers

ityM

etro

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lth

Med

ical

Cen

ter

NA

SA

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nn

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earc

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ente

r

Col

labo

rato

rs:

Bet

h Le

wan

dow

ski,

NA

SA

Gle

nn R

esea

rch

Cen

ter

Kev

in K

ilgor

e, M

etro

Hea

lth M

edic

al C

ente

rK

enne

th G

usta

fson

, Cas

e W

este

rn R

eser

ve U

nive

rsity

3

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RA

TIO

NA

LE F

OR

PR

OJE

CT

•Fu

nctio

nal e

lect

rical

stim

ulat

ion

(FE

S) i

s a

met

hod

whe

re e

lect

rical

cu

rren

t is

appl

ied

to th

e ne

rvou

s sy

stem

to re

stor

e or

impr

ove

the

func

tion

of a

sys

tem

com

prom

ised

by

para

lysi

s–

Mot

or fu

nctio

n–

Res

pira

tion

–Bl

adde

r and

bow

el fu

nctio

n

•M

ost F

ES

dev

ices

are

impl

ante

d in

to th

e bo

dy a

nd

need

ele

ctric

al p

ower

for o

pera

tion.

•C

urre

nt p

ower

sou

rces

incl

ude:

–Im

plan

ted

batte

ries

–Tr

ansc

utan

eous

pow

er s

ourc

es

•A

reas

for i

mpr

ovem

ents

:–

Red

uce

repl

acem

ent s

urge

ries

–Al

low

tim

e w

ithou

t ext

erna

l equ

ipm

ent

•In

crea

se in

depe

nden

ce (a

llow

FE

S u

se in

a w

et e

nviro

nmen

t)•

Red

uce

equi

pmen

t mal

func

tion

(wire

con

nect

ions

, coi

l mis

alig

nmen

t)

4

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PR

OJE

CT

OB

JEC

TIV

E

Det

erm

ine

the

feas

ibili

ty o

f usi

ng s

timul

ated

m

uscl

e to

pow

er a

sel

f-sus

tain

ing,

tota

lly

impl

anta

ble

pow

er s

ourc

e fo

r im

plan

ted

FES

de

vice

s.

5

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PIE

ZOE

LEC

TRIC

GE

NE

RA

TOR

CO

NC

EP

T

Nerv

e

TendonB

one

Bon

e Muscle

Mus

cle Bon

e

Bon

e

Tend

on

6

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iona

l Aer

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PIE

ZOE

LEC

TRIC

GE

NE

RA

TOR

CO

NC

EP

T

Nerv

e

Bon

e

Bon

e Muscle Tendon

Mus

cle Bon

e

Bon

e

Tend

on

7

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iona

l Aer

onau

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and

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PIE

ZOE

LEC

TRIC

GE

NE

RA

TOR

CO

NC

EP

T

Nerv

e

Muscle

Pie

zoel

ectri

c ge

nera

tor

Bon

e

Bon

e Tendon

Stim

ulat

ed m

uscl

e po

wer

ed p

iezo

elec

tric

gene

rato

r

Mus

cle Bon

e

Bon

e

8

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iona

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PIE

ZOE

LEC

TRIC

GE

NE

RA

TOR

CO

NC

EP

T

Nerv

e Stim

ulat

or

nerve electrode lead

Muscle B

one

Bon

e

Pie

zoel

ectri

c ge

nera

tor

Tendon

Ner

ve e

lect

rode

Lead

to n

erve

el

ectro

de

Stim

ulat

ed m

uscl

e po

wer

ed p

iezo

elec

tric

gene

rato

r

Mus

cle Bon

e

Bon

e

9

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iona

l Aer

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tics

and

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e Ad

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tion

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Ner

ve e

lect

rode

Lead

to n

erve

el

ectro

de

Stim

ulat

ed m

uscl

e po

wer

ed p

iezo

elec

tric

gene

rato

r

PIE

ZOE

LEC

TRIC

GE

NE

RA

TOR

CO

NC

EP

T

Nerv

e Stim

ulat

or

nerve electrode lead

Muscle B

one

Bon

e

Mus

cle Bon

e

Bon

e

Ene

rgy

stor

age

circ

uitry

Pie

zoel

ectri

c ge

nera

tor

Tendon

10

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iona

l Aer

onau

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tion

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Ner

ve e

lect

rode

Lead

to n

erve

el

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de

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ulat

ed m

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tric

gene

rato

r

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cle

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e

Bon

e

PIE

ZOE

LEC

TRIC

GE

NE

RA

TOR

CO

NC

EP

T

Nerv

e Stim

ulat

or

nerve electrode lead

Muscle B

one

Bon

e

Lead to application

Ene

rgy

stor

age

circ

uitry

Lead

to a

pplic

atio

nP

iezo

elec

tric

gene

rato

rTendon

Connection to stimulator

11

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iona

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PR

OJE

CT

UN

IQU

EN

ES

S

•Th

e sy

stem

use

s no

mov

ing

parts

and

con

tain

s a

natu

ral

conn

ectio

n in

ser

ies

with

the

mus

cle

tend

on u

nit

–P

revi

ous

impl

ante

d ge

nera

tor d

esig

ns th

at u

se m

otio

n fo

r op

erat

ion

have

suf

fere

d fro

m re

duce

d ef

ficie

ncy

durin

g ch

roni

c op

erat

ion

•Th

e sy

stem

leve

rage

s th

e po

wer

am

plifi

catio

n ch

arac

teris

tic o

f mus

cle

–M

ore

outp

ut p

ower

is a

vaila

ble

from

a m

uscl

e th

an is

nee

ded

for

elec

trica

l stim

ulat

ion

of th

e m

otor

ner

ve–

Gai

n is

ach

ieve

d th

roug

h ch

emic

al e

nerg

y st

ored

in th

e m

uscl

e

•Fo

r neu

ral p

rost

hesi

s ap

plic

atio

n th

e co

ncep

t use

s a

para

lyze

d m

uscl

e fo

r whi

ch re

stor

atio

n of

func

tion

is n

ot

antic

ipat

ed.

12

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STE

PS

TO

DE

TER

MIN

E F

EA

SIB

ILIT

Y

•A

sof

twar

e ci

rcui

t mod

el w

as d

evel

oped

and

use

d to

:–

Und

erst

and

syst

em p

aram

eter

s–

Est

imat

e ou

tput

pow

er

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echa

nica

l tes

ts w

ere

cond

ucte

d to

:–

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erm

ine

the

accu

racy

of t

he s

oftw

are

mod

el–

Test

a m

echa

nica

l hol

der f

or th

e pi

ezoe

lect

ric g

ener

ator

•Te

st in

an

acut

e an

imal

mod

el–

Dem

onst

rate

forc

e ap

plic

atio

n w

ith a

phy

siol

ogic

al s

ourc

e–

Dem

onst

rate

clo

sed-

loop

sys

tem

ope

ratio

n

13

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SO

FTW

AR

E M

OD

EL

OF

SY

STE

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Af

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fCV

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rm

pmp

opt

out

44

22

332

==

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g 33

=

tA

EnE

or

=

LssL

out

RVP

2

=

+ V L -

Load

circ

uit

Inpu

t for

ce

from

mus

cle

Gen

erat

oran

d ci

rcui

t

Out

put

pow

er

14

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iona

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SY

STE

M P

AR

AM

ETE

RS

14 –

54

mV

*m/N

g 33 an

d E r

have

an

inve

rse

rela

tions

hip

Ava

ilabi

lity

of m

ater

ial

Max

imiz

eg 3

3P

iezo

elec

tric

cons

tant

400

-580

0A

vaila

bilit

y of

mat

eria

l M

axim

ize

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ctric

co

nsta

nt

0.5

–2

Hz

F m a

nd f

have

an

inve

rse

rela

tions

hip

Mus

cle

fatig

ueM

axim

ize

fFr

eque

ncy

of

inpu

t for

ce

10 –

250

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and

f ha

ve a

n in

vers

e re

latio

nshi

pS

ize

of m

uscl

e an

d st

imul

atio

n pa

ram

eter

sM

axim

ize

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eak

inpu

t fo

rce

0.06

–4

cm2

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t mai

ntai

n a

prop

er ra

tio w

ith L

Mus

t be

able

to b

e m

achi

ned

Min

imiz

eA

Are

a

50 –

200

mm

L =

n*t,

Mus

t mai

ntai

n a

prop

er ra

tio w

ith A

W

ill b

e ap

prox

imat

ely

the

leng

th o

f the

tend

onM

axim

ize

LLe

ngth

0.13

–2

mm

Can

be

used

to s

et

outp

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olta

geS

pace

ava

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e fo

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plan

tatio

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axim

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of

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used

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et

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olta

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ava

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ge o

f po

ssib

le

valu

es

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atio

nshi

p w

ith

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r par

amet

ers

Phys

ical

or

phys

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gica

l co

nstr

aint

s

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imiz

e or

m

inim

ize

for

max

pow

er

Sym

bol

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met

er

3371

187

,13

gr

eE

−=

15

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PR

ED

ICTE

D O

UTP

UT

PO

WE

R F

OR

TH

RE

E

SC

EN

AR

IOS

*Hig

h va

lue

calc

ulat

ed fr

om 5

00 μ

s, 1

mA

puls

es a

cros

s 10

00 Ω

at 3

0 H

z fo

r 250

ms

per c

ontra

ctio

n at

1 H

z.

Low

val

ue is

cal

cula

ted

from

sin

gle

puls

es o

f 500

μA

for 2

00 μ

s ac

ross

100

0 Ω

at 1

Hz.

*

16

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ME

CH

AN

ICA

L TE

ST

PR

OC

ED

UR

E

A M

TS m

achi

ne w

as u

sed

to a

pply

in

put f

orce

at 1

Hz

with

pea

k va

lues

of

25,

50,

100

, 150

, 200

and

250

N to

a

lead

zirc

onat

etit

anat

e(P

ZT)

piez

oele

ctric

sta

ck g

ener

ator

(par

t nu

mbe

r T18

-H5-

104,

Pie

zoS

yste

ms,

In

c. C

ambr

idge

, MA

).

Com

pres

sive

forc

e w

as a

pplie

d di

rect

ly to

the

stac

k an

d te

nsile

forc

e w

as a

pplie

d to

a h

olde

r for

the

piez

oele

ctric

sta

ck.

In v

ivo,

the

hold

er w

ill a

ttach

the

piez

oele

ctric

sta

ck to

the

tend

on a

nd to

th

e bo

ne.

The

tens

ile fo

rce

from

the

mus

cle

will

pu

ll on

the

hold

er, w

hich

will

cau

se

com

pres

sive

forc

e to

be

appl

ied

to th

e st

ack

betw

een

the

two

plat

es.

Mec

hani

cal t

ests

wer

e pe

rform

ed to

de

term

ine

if th

ere

are

loss

es a

ssoc

iate

d w

ith th

e m

echa

nica

l cou

plin

g

17

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ME

CH

AN

ICA

L TE

ST

RE

SU

LTS

Sim

ulat

ion

resu

lts

mat

ch

expe

rimen

tal

resu

lts, v

erify

ing

accu

racy

of

mod

el

Ver

y lit

tle

mec

hani

cal

coup

ling

loss

es

occu

r whe

nus

ing

hold

er

The

stac

k w

as

conn

ecte

d to

the

diod

e br

idge

and

load

circ

uit

and

outp

ut v

olta

ge w

as

mea

sure

d ac

ross

the

load

resi

stor

LssL

out

RVP

2

=

The

stea

dy s

tate

vo

ltage

was

use

d to

ca

lcul

ate

outp

ut

pow

er

18

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AN

IMA

L TE

ST

PR

EP

AR

ATI

ON

S•

The

rabb

it qu

adric

eps

is b

eing

use

d as

the

anim

al

mus

cle

mod

el–

The

twitc

h fo

rce

has

been

ver

ified

to b

e be

twee

n 30

and

50

N.

•Th

e te

st s

tand

and

con

nect

ion

to te

ndon

can

with

stan

d:–

15 lb

s (6

7 N

) of s

tatic

wei

ght

–D

ynam

ic fo

rces

con

sist

ing

of p

eak

forc

es o

f 60

N

•B

lock

dia

gram

of t

he te

st s

tand

:

Test stand baseForce

transducer

Pie

zoel

ectri

c ge

nera

tor i

n ho

lder

Turn

buck

leM

uscl

e

Test stand support

Rab

bit

19

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iona

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and

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AN

IMA

L TE

ST

PR

OTO

CO

L•

Set

up

test

sta

nd–

Forc

e tra

nsdu

cer

–Pi

ezoe

lect

ric g

ener

ator

in h

olde

r, a

Lead

Mag

nesi

um N

ioba

test

ack

gene

rato

r was

use

d (T

RS

C

eram

ics,

PM

N 3

2%PT

Act

uato

r)–

Con

nect

the

piez

oele

ctric

gen

erat

or to

the

stor

age

circ

uit

•P

erfo

rm s

urge

ry–

Expo

se p

atel

lar t

endo

n, d

isco

nnec

t fro

m ti

bia,

dril

l hol

e th

roug

h pa

tella

, pul

l wire

thro

ugh

hole

an

d cr

imp

–Ex

pose

the

fem

oral

ner

ve a

nd p

lace

a c

uff e

lect

rode

aro

und

the

nerv

e

•C

onne

ct ra

bbit

to te

st s

tand

–C

onne

ct w

ire b

etw

een

pate

lla a

nd tu

rnbu

ckle

/gen

erat

or/fo

rce

trans

duce

r–

Use

tie

wra

p to

con

nect

the

tibia

/fem

ur to

the

test

sta

nd

•Fi

nd s

timul

atio

n pa

ram

eter

s–

Adju

st th

e m

uscl

e le

ngth

to th

at w

hich

pro

duce

s m

axim

um fo

rce

–Fi

nd th

e th

resh

old

curre

nt fo

r pro

duci

ng m

axim

um tw

itch

forc

e

•R

un E

xper

imen

t–

Stim

ulat

e fe

mor

al n

erve

–

Rec

ord

the

volta

ge a

cros

s th

e lo

ad re

sist

or

20

Nat

iona

l Aer

onau

tics

and

Spac

e Ad

min

istra

tion

ww

w.n

asa.

gov

AN

IMA

L TE

ST

RE

SU

LTS

Ave

rage

pea

k fo

rce

= 32

NV

olta

ge g

ain

= 0.

3 V

Out

put p

ower

= 3

0 nW

Cha

rgin

g tim

e =

74 s

ec

Ave

rage

pea

k fo

rce

= 60

NV

olta

ge g

ain

= 1.

7 V

Out

put p

ower

= 1

µW

Cha

rgin

g tim

e =

85 s

ec

Twitc

h C

ontr

actio

ns

Teta

nic

Con

trac

tions

The

prot

otyp

e ge

nera

tor s

yste

m w

as c

harg

ed

with

a p

hysi

olog

ical

mus

cle

21

Nat

iona

l Aer

onau

tics

and

Spac

e Ad

min

istra

tion

ww

w.n

asa.

gov

IMP

RO

VE

ME

NTS

/FU

TUR

E W

OR

K•

Cur

rent

out

put p

ower

leve

ls a

re b

elow

pre

dict

ed v

alue

s.

Impr

ovem

ents

that

can

be

mad

e to

impr

ove

outp

ut p

ower

.–

Nee

d to

ens

ure

piez

oele

ctric

gen

erat

or is

squ

are

with

hol

der a

ndfo

rce

is o

nly

appl

ied

in d

irect

ion

norm

al to

the

cros

s se

ctio

nala

rea

of th

e ge

nera

tor.

–U

se lo

w p

ower

dio

des

in a

n ef

fort

to in

crea

se o

utpu

t pow

er le

vels

.–

Exp

lore

stim

ulat

ion

para

met

ers

to m

axim

ize

outp

ut p

ower

. A tr

ade-

off e

xist

s be

twee

n in

put s

timul

atio

n po

wer

and

out

put f

orce

pr

oduc

ed b

y th

e m

uscl

e.

•Th

e in

put p

ower

nec

essa

ry fo

r the

mot

or n

erve

stim

ulat

ions

was

gr

eate

r tha

n th

e ou

tput

pow

er d

urin

g th

e fir

st a

nim

al e

xper

imen

t.

–A

siz

e co

rrec

tion

and

impr

ovem

ent i

n el

ectro

de p

lace

men

t will

re

duce

the

amou

nt o

f stim

ulat

ion

inpu

t pow

er n

eede

d.

•U

se a

low

pow

ered

stim

ulat

or a

nd c

ircui

try to

dem

onst

rate

sel

f-su

stai

ning

stim

ulat

ed m

uscl

e co

ntra

ctio

ns a

nd p

ower

ge

nera

tion.

22

Nat

iona

l Aer

onau

tics

and

Spac

e Ad

min

istra

tion

ww

w.n

asa.

gov

AC

KN

OW

LED

GE

ME

NTS

•C

omm

ittee

:–

Dr.

Ken

Gus

tafs

on, C

WR

U B

ME

Dep

artm

ent

–D

r. K

evin

Kilg

ore,

CW

RU

BM

E D

epar

tmen

t–

Dr.

Ste

ve G

arve

rick,

CW

RU

EE

CS

Dep

artm

ent

–D

r. B

ob K

irsch

, CW

RU

BM

E D

epar

tmen

t–

Dr.

Dus

tin T

yler

, CW

RU

BM

E D

epar

tmen

t

•In

add

ition

:–

Mr.

Fred

Mon

tagu

e, C

ase

Tech

nica

l Dev

elop

men

t Lab

orat

ory

–M

s. K

atie

Hal

laha

n, C

WR

U S

tude

nt–

Mr.

Ale

x Fr

ayna

, CW

RU

Stu

dent

–D

r. Y

orda

nK

osto

v, U

MB

C C

hem

ical

& B

ioch

emic

al E

ngin

eerin

g–

Mr.

Rog

er D

iam

ond,

LC

CC

Eng

inee

ring

Dep

artm

ent

–D

r. S

kip

Lew

ando

wsk

i, B

W B

usin

ess

Div

isio

n

•Fu

ndin

g:–

This

pro

ject

is fu

nded

by

NA

SA

Gle

nn R

esea

rch

Cen

ter’s

Hum

an R

esea

rch

Pro

gram

of t

he E

xplo

ratio

n S

yste

ms

Div

isio

n an

d by

the

Mic

rogr

avity

Sc

ienc

e D

ivis

ion,

NIH

HD

4029

8 an

d Th

e S

tate

of O

hio

BR

TT 0

3-10

.

23

Nat

iona

l Aer

onau

tics

and

Spac

e Ad

min

istra

tion

ww

w.n

asa.

gov

QU

ES

TIO

NS

AN

D C

OM

ME

NTS

?