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U n i t e d S t a t e s P a t e n t [i9]Goldman

U S 0 0 5 4 4 9 0 0 2 A[11] Patent Number:[45] Date of Patent:

5,449,002Sep. 12, 1995

[54] C A P A C m V E B I O F E E D B A C K S E N S O RW I T H R E S I L I E N T POLYURETHANED I E L E C T R I C F O R R E H A B I L I T A T I O N[76] Inve n to r : R o be r t J . G o ldma n , 3607 B a r ing S t . ,PhU a de lph ia , Pa . 19104[21 ] A p p l . N o . : 908 ,121[22] Fi le d: Ju l . 1 , 1992[51] In t . a. 6 A 6 1 B 5 / 1 0 3[52] U . S . a 128 /7 79 ; 128 /782 ;128 /774 ; 340 /573 ; 361 /291[58] Fie ld of Search 128/7 74, 779, 782, 905;7 3 / 1 7 2 ; 340 /573 ; 361 /290 . 291[56] Referen ces Ci ted

U . S . P A T E N T D O C U M E N T S3,702,999 11/1972 Gradisa r 340/2723,791,375 2/1974 Pfeiffer .3,974,491 8/1976 Sipe 340/ 2724,426,884 1/1984 Polchaninoff 73/1724,503,705 3/1985 Polchaninoff 73/17 24,617,525 10/1986 Llo yd 340/5734,647,918 3/1987 Gofo rth 340/5734,745,930 5/1988 Confer 128/7794,852,443 8/1989 Duncan etal 84/1.045,060,527 10/1991 Burgess 73/862.685,081,447 1/1992 Echols 340/5735,209,240 5/1993 Jain et al 128/7795,323,650 6/1994 Fullen et al 73/172

F O R E I G N P A T E N T D O C U M E N T S0415036 3/1991 Euro pean Pat. Off. 128/7792675370 10/1992 Fra nce 128/7793812287 10/1989 Germ any 128/7794135940 5/1993 Germ any 128/779

O T H E R P U B L I C A T I O N SE n d i c o t t e t a l L e g L o a d . . . h a n d i c a p p e d M e d i c a la nd B io log ic a l En g ine e r ing , M a y 1974 pp . 318 -320 .

T h e L i m b L o a d M o n i t o r : A n A u g m e n t e d S e n s o r yF e e d b a c k D e v i c e , R . C r a i k e e t al . . D e v i c e s a n d S y s t e ms fo r t he D i sa b le d , A pr . 29 & 30, 1975, Spo nso r e d byK r u s e n C e n t e r fo r R e s e a r c h & E n g i n e e r i n g a t M o s sR e ha b i l i t a t i on H osp i t a l pp . 18 -24 .C a p a c i t i v e T r a n s d u c e r f o r C o n t i n u o u s M e a s u r e m e n to f V e r t i c a l Foo t Fo rc e , S . Miya z a k i , A . I sh ida ; M e d . &B i o l o g . E n g & C o m p u t i n g , 1 9 84 , 2 2 . pp. 309 to 316.P r o c e e d i n g s o f t h e N i n t h A n n u a l C o n f e r e n c e o f t h eI E E E / E n g i n e e r i n g ia Me d ic ine a nd B io logy Soc ie ty ,

T h e B o s t o n P a r k P l a z a H o t e l , B o s t o n , M a s s . N o v .13 -16 , 1 98 7 . P r e s s u r e M o n i t o r i n g U n d e r I n s e n s a t eFe e t Ma a le , e t a l .R E S N A , 13 th A n nua l C onfe re nc e , 1990 , pp . 201 , 202W. H yma n e t a l .F o o t & A n k l e / v o l . 9 , N o . 3 / D e c . , 1 9 88 , O b j e c t i v eEva lua t ion o f In se r t Ma te r i a l fo r D ia be t i c a nd A th le t i cF o o t w e a r , J . W. B r ods ky e t a l . pp . 111 -116 .Se nso rs , M a y 1991 , pp . 21 -25 Te c s c a n I nc .E . Q . , I n c . 6 00 G a l a h a d R o a d , P l y m o u t h M e e t i n g , P a . ,19462 , En g in e e r in g too l s fo r r e ha b i l i t a t i on the r a pyD a t e u n k n o w n .F - S C A N : I n t r o d u c i n gF - S C A N , T e k s c a n , I n c .( D a t e u n k n o w n ) .B i o m e c h a n i c a l S tu d i e s : A M e t h o d o f M e a s u r i n g F o o tP r e s s u r e s U s i n g A H i g h R e s o l u t i o n , C o m p u t e r i z e dInso le Se nso r : The Ef fe c t o f H e e l W e dge s on P la n t a rP r e s s u r e D i s t r i b u t i o n a n d C e n t e r o f F o r c e , N i c h o l a rM . R o s e , M . D . , L a w r e n c e A . F e i w e U , M . D . , A n d r e aC r a c c h i o l o I I , M . D . p . 1 0, d a t e u n k n o w n .C o m b i n e d M e e t i n g o f t h e t h e O r t h o p a e d i c R e s e a r c hS o c i e ti e s o f U S A , J a p a n & C a n a d a : A N e w F l e x b i l eS e n s o r t o E v a l u a t e D y n a m i c In-Shoe P l a n t a r P r e s s u r eD u r in g G a i t a nd I t s U se to M e a su r e the Ef fe c t o f S hoeA c c o m m o d a t i o n D e v i c e s I n S e v e r e M e t a t a r s a l g i a , B .J . A m bre y , M.D . , R . B . Esko v i t z , C . A . R ic he l e n , R . M .Podo lo f f a nd M. H . B e n ja min , p . 1, da t e u nkn ow n .A F le x ib l e P r in t e e d C i rc u i t B oa rd fo r Mon i to r ingP a t t e r n s o f F o o t L o a d i n g , C r a i g A . K i r k w o o d , B . S c ,a n d B r i a n J . A n d r e w s , P h . d . , I C A A R T 8 8 - M o n t r e a l ,p p . 4 8 8 - 4 8 9 , da t e vmknow n .Primary ExaminerStephen C . Pe l l e g r in oAssistant ExaminerGuy V . T u c k e rAttorney Agent orFirmMorgan & F i n n e g a n[57] A B S T R A C Ta c a pa c i t i ve b io fe e dba c k se nso r i nc lud ing a po lyu re -t h a n e d i e l e c t r i c s a n d w i c h e d b e t w e e n t w o w i r e m e s h o rc a r b o n i m p r e g n a t e d s i li c o ne r u b b e r c o n d u c t o r s . T h ese nso r i s p l a c e d w i th in a pa t i e n t ' s shoe , boo t , a nk le ,b ra c e , c ru t c h , ha nd r ip , w he e lc ha i r , e t c . , a nd p rov i de sb io fe e dba c k to he lp pa t i e n t s r e l e a m func t ion o r p re v e n tc ompl i c a t ions tha t impe de func t ion .

20 O a ims , 7 D ra w ing She e t s^54

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U . S . Pa ten t S e p . 12, 1995 Sheet 5 of 7 5,449,002

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5,449,002C A P A C m V E B IO F E E D B A C K S E N S O R W I T HR E S I L I E N T P O L Y U R E T H A N E D I E L E C T R I C F O RR E H A B I L I T A T I O N 5B A C K G R O U N D O F I N V E N T I O NThis i nve n t ion re l a t e s t o a ppa ra tu s fo r me d ic a l a ndthe ra pe u t i c a pp l i c a t ion a nd , more pa r t i c u l a r ly , t o a

se nso r fo r p rov id in g b io fe e dba c k s igna l s t o he lp p a t i e n t sre l e a m va r ious phys i c a l func t ions , o r t o p re ve n t c om- ^p l i c a t ions tha t impe de the se phys i c a l func t ions .F re que n t ly , i t i s de s i r a b l e t o obse rve the me c ha n ic a lp re ssu re a pp l i e d in pe r fo rming some o the rw i se rou t inephy sica l func t ion , no t only by a pa t ie nt suffe r ing froms o m e Ulness o r d i sa b il i t y , bu t a l so f rom a r e c o ve r i ng ^^pa t i e n t , w ho i s t ryiag to r e ga in , o r a t l e a s t t o improvesome phys i c a l func t ion . Th i s ne e d to obse rve the me c ha n ic a l p re ssu re a pp l i e d by the pa t i e n t i n pe r fo rm ing apa r t i c u l a r func t ion a l so e x t e nds t o pa t i e n t s w ho re qu i reb ra c e s o r o the r o r tho t i c a ppa ra tu s , as w e l l a s t o p ro s - 20the t ic equipment , or a r t i f ic ia l l imbs, and assis t devices ofw hic h c ru t c he s , w he e lc ha i r s a nd the l i ke a re t yp i c a l .U nc onsc ious o r i nvo lun ta ry bod i ly p roc e sse s , fo re xa mple , t he p re ssu re d i s t r i bu t ion a pp l i e d by the so l e o fa foo t t o t he i nne r so l e o f a shoe w hi l e w a lk ing , t he 25a c t ion o f t he a nk le , also w h i l e \valkingo r , t he a pp l i c a t i on o f bod i ly w e igh t t o a pa i r o f c ru t c he s a nd the l i ke ,i f ma de pe rc e p t ib l e t o t he se nse s c a n in ma ny in s t a nc e sb e m o d i f i e d t h r o u g h c o n s c i o u s m e n t a l c o n t r o l t o p r o duc e a p rope r ga i t , o r t o de ve lop the c o r re c t u se o f 30c ru t c he s i n o rde r t o a vo id impa i r ing those ne rve s tha tc on t ro l a rm mo ve m e n t a nd se nsa t ion , t he b r a c h ia lp l e xus . Th i s t r e a tm e n t t e c hn iqu e , o f te n r e fe r re d t o a sb io fe e dba c k , i s be ne f i c ia l . U nfo r t ima te ly , kn ow n b io fe e dba c k t e c hn ique s a nd e qu ipme n t a re unsa t i s fa c to ry 35fo r a num be r o f r e a sons a nd , a s a c ons e que nc e a r e no t i nge ne ra l u se by pa t i e n t s e i t he r i n a c u te c a re , r e ha b i l i t a t ion or a t home in sp i te of the need for devices of th isn a t u r e . H o w e v e r , t h e n e e d f o r t h e m i s c o m p e l l i n g .F o r i n s t a nc e , b io fe e dba c k m a y p rov id e fo r mon i to r - 40ing the w e igh t a pp l i e d to a l imb ( l imb loa d mon i to r i n g ) . A n im por t a n t e xa mple o f t h i s l imb loa d mo n i to r ing r e l a t e s t o l im i t ing the w e igh t t ha t i s bo rn e by thelimb w h e n re c o ve r in g f rom l e g f r a c tu re o r j o in t r e p l a c e m e n t . To ta l h ip r e p l a c e m e n t s a lone a re pe r fo rme d 45200 ,000 t ime s pe r ye a r i n t he U n i t e d S t a t e s a nd toe -t o u c h o r p a r t i a l w e i g h t b e a r i n g i s a l m o s t a l w a y sp re sc r ibe d fo r t he r e c ove r ing pa t i e n t by the su rge on .Pa r t i a l w e igh t be a r ing c on t inue s un t i l he a l ing ha s p rog ressed suff ic ient ly to a l low the pa t ient to apply fu l l 50w e igh t t o t he r e c ove r ing me mbe r sa fe ly . In a lmos t a l lr e ha b i l i t a t i on c e n te r s , how e ve r , t he r e i s no w^ay to a s su re c om pl i a nc e w i th th i s p re sc r ib e d t r e a tm e n t e xc e p tt h r o u g h o b s e r v a t i o n b y t r a i n e d p e r s o n n e l . A l t h o u g hthe t rue c os t o f e xc e ss ive w e igh t be a r ing in t he se c i r - 55c umsta nc e s doe s no t se e m to ha ve be e n sys t e ma t i c a l lys tud ie d , i t i s ne ve r the l e ss r e a sona b le t o a ssume tha t t h i sfa i l u re t o sy s t e ma t i c a l ly c on t ro l t he w e igh t bo rne by ar e c o v e r i n g Umb p ro long s he a l ing time , i nc re a se s t hedu ra t io n o f hosp i t a l i z a t ion a nd pa t i e n t de pe nd e n t s t a tu s . 60Thus , i t se e ms tha t a r e l i a b l e a ppa ra tu s fo r sy s t e ma t i c a l ly mon i to r ing the l oa d a pp l i e d to a r e c ove r ing l imbc ou ld s ign i f i c a n t ly r e duc e th i s a ppa re n t l o ss i n pa t i e n tre c ove ry t ime a nd the e ffo r t r e qu i re d o f t r a ine d the ra pists as we l l as red uc ing ineff icient u se of me dic a l facUi- 65t i e s a nd a t t e n da n t e xpe nse .

In a dd i t i on to t he ne e d fo r improve d re ha b i l i t a t i ont e c hn ique s , de sc r ibe d a bove , t he re a re a numbe r o f

a pp l i c a t ions o f l imb loa d mon i to r ing to ga i t t r a in ing .L i m b l o a d d e v i c e s w o u l d h e l p a m p u t e e s t o a p p l yw e igh t t o p ro s the t i c l imbs in a symme t r i c a l ma nne r a s ap r e l u d e t o p r o g r e s s i v e a m b u l a t i o n . C h i l d r e n w i t h c e r e b ra l pa l sy migh t be t a ugh t t o w a lk c o r re c t ly by placingw e igh t on the he e l a nd s top w a lk ing w i th a n e qu ine , o rdow nw a rd ly po in t ing a nk le . In t h i s w a y , i npa t i e n t r e ha b i l i t a t i on se rv i c e t ime c ou ld be r e duc e d , a nd sa fe a mbul a t i o n p r o m o t e d .O the r po te n t i a l a pp l i c a t ions i nc lude rew^arding thepa t i e n t fo r me e t ing o the r s t r e ng th goa l s . I l l u s t r a t i ve ly ,de ve lop ing musc u la r c on t ra c t ions w i thou t s ign i f i c a n t lyshortening the musc le f iber in the hand or knee , tha t i s ,i some t r i c g r ip s t r e ng th a nd kne e s t r e ng th migh t be imp r o v e d t h r o u g h b i o f e e d b ac k t e c h n i q u e . F u r t h e r , i n d i v idua l s w i th rhe uma t i c d i se a se s a l so c ou ld g re a t ly be ne f it f rom effec t ive l imb load m oni tor i ng .A no the r g roup o f pa t i e n t s , su f fe r ing f rom d i sa b i l i t i e stha t c on f ine the m e i the r pe rma ne n t ly o r t e mpora r i l y t oa w he e lc ha i r a l so cotoldbenefi t f rom a pra c t ic a l appl ic at i on o f b io fe e dba c k to t he i r s t a tu s . Pa ra p le g i c s , pe r sonsw i t h sp ina b i f i da a nd o the r s w ho l a c k fe e ling o r se nsa t i on be low the w a i s t w ou ld be ne f i t f rom a b io fe e dba c ks igna l , c u ing th e m to sh if t t he i r w e igh t on th e se a t o f t hewheelcha ir and reduce the possib i l i ty of sacra l pressureu lc e r s . S t il l a no the r g rou p o f pa t i e n t s , bou nd to w he e l c ha i r s , a re t hose su f fe r ing f rom me n ta l de t e r io ra t iona nd s t roke s . In e i t he r i n s t a nc e , fa l l ing f rom a w h e e lc ha i ri s a n a l l - t oo -c ommon in ju ry fo r pa t i e n t s o f t h i s na tu rea nd some b io fe e dba c k me c ha n i sm tha t c ou ld loc k thewh eel ch a ir brak es before r is ing from the whee lcha irw o u l d r e d u c e i n j u r y a n d p r o m o t e s a f e t y a w a r e n e s s .Natura l ly , a grea t dea l of e ffor t has been appl ied tod e v e l o p a p p a r a t u s t h a t wUl p rov ide a r e l i a b l e , i ne xpe n s ive a nd a c c u ra t e b io fe e dba c k de v ic e . The se e f fo r t sinvo lve d a numbe r o f t e c hno log ie s t ha t c a n be c a t e go r i z e d , ge ne ra l ly , a s c a pa c i t i ve , r e s i s t i ve , hyd ra u l i c ,pnetunatic a nd a l so o f a ge ne ra l , m i sc e l l a ne ous c ha ra c t e r fo r p rov id ing a n a c c u ra t e me a su re o f t he p re ssu reappl ied by a pa t ient to a surface .C a pa c i t i ve t r a nsduc e r s fo r b io fe e dba c k ope ra t ionha ve inhe re n t be ne f i t s i n mon i to r ing the l oa d ing onl imbs o r on o the r body pa r t s . A s the w e igh t o f a pa t i e n tis apphed to a me a su r ing c a p a c i to r , t he re i s a r e l a t i ve lyl ine a r iacrease o f c a pa c i t a nc e w i th a pp l i e d w e igh t ,w h ic h pe rmi t s t he u se o f s imp le , l ow c os t e l e c t r i c a lc i r c u i t s t o ge ne ra t e a s igna l t ha t i s d i r e c t ly p rop o r t ion a lto t he a pp l i e d w e igh t . In t h i s w a y , a c a pa c i t i ve t r a ns duc e r migh t be de ve lope d to me a su re the t o t a l w e igh tth a t i s app l ied to com plex , i r regul ar surfaces. In sp i te ofth i s po t e n t i a l , c a pa c i t i ve t r a nsduc e r s ha ve be e n ove r looke d du r ing mos t o f t he pa s t de c a de in f a vo r o f r e s i s t i ve de v ic e s . W ha t ha s be e n l a c k ing , a nd m a d e c a pa c i t i ve t r a nsduc e r r e se a rc h fo r t h i s pu rpose una t t r a c t iveha s be e n the l a c k o f a n a c c e p ta b le d i e l e c t r i c .

T he d i e l e c t r i c i s t he i n su l a t i ng midd le l a ye r t ha t i si n t e rpose d be tw e e n the e l e c t r i c a l ly c onduc t ive p l a t e stha t c ompr i se t he c a pa c i to r . O rd ina r i l y , t he d i e l e c t r i cp rope r t i e s r e ma in c ons t a n t a s a fo rc e , suc h a s t ha t a p p l i e d by a l imb , c om pre sse s t he d i e l e c t r i c a nd b r ings th ec onduc t ive p l a t e s c lo se r t oge the r t he re by c a us ing thec a pa c i t a nc e o f t he se nso r t o i nc re a se me a su ra b ly .Ma ny d i e l e c t r i c s , how e ve r , a re sub je c t t o c re e p ,w h ic h i s t he l ong t e r m c ha n ge in t he d i e l e c t r i c t h i c kne ssa f t e r i n i t i a l l oa d ing . D ie l e c t r i c s a l so a re sub je c t t o hys t e re s i s , w h ic h i s t he d i f f e re nc e in c ompre ss ion , o r c a pa c i t a nc e , a t a g ive n loa d w i th the l oa d inc re a s ing , a nd

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5,449,0023 4w i t h the l oa d de c re a s ing . Th e se ns it i v i t y o f t he d i e l e c - e x t e nd e d u se fo r t h i s t r a ns duc e r a nd i t ma y be u se d w i tht r i e , o r t he r a t i o o f c a pa c i t a n c e in t he l oa de d a nd un - s imp le e l e c t r i c a l c i r c u i t s .l oa de d s t a t e , pe r a pp l i c a t ion o f un i t w e igh t a l so i s a n F o r t he se r e a sons FS R 's ha v e be e n p ropo se d fo ri m p o r t a n t p a r a m e t e r . T h e s p e e d w i t h w h i c h t h e s e n s o r e v e r y d a y rehabiUtation p re ssu re me a su re me n t i n se v -ach iev es s teady sta t e a f te r weight i s appl ied , or the 5 eral a pp l i c a t ions . The se inc lude mon i to r ing p re ssu redyn a m ic r e spons e o f t he d i e l e c t r i c a nd the r e s i l i e nc y o f und e r i n se nsa t e fe e t i n pa t i e n t s a ff l ic t ed w i t h d i a be t e sthe d i e l e c t r i c , w h ic h i s t he a b i li t y o f t he d i e l e c t r i c t o a nd l e p ro sy (M . Ma a le j , e t . a l . , IE E E , 9 th C onfe re nc ere t a in i t s un loa d e d th i c kne s s a nd ba se l ine c a pa c i t a nc e o f t he Eng ine e r ing in Me d ic ine a nd B io logy So c ie ty ,a f te r a lo ng dura t ion of s ta t ic or dy nam ic loading a lso 1987, pp . 1824, 1824) . A f inger and ha nd exerc ise dev icea re s ign i fi c a n t f a c to r s i n c hoos ing su i t a b l e d i e l e c t r i c s . 10 a nd sp o t h igh p re ssu re se nso r t o p re ve n t sa c ra l p re s -Al l o f t he se p rope r t i e s a re a func t ion o f t he d i e l e c t r i c su re u l c e r s ha v e a l so be e n de sc r ibe d (H y ma n , W . e t . a l . ,ma te r i a l c ompos i t i on a nd s t ruc tu re . Ide a l ly , fo r t he RESNA 13th annua l Confe ren ce , 1990, pp . 201 , 202) . I tpu rp ose o f a b io fe e dba c k se nso r , a d i e l e c t r i c shou ld a dd i t i ona l ly ha s be e n p rop ose d fo r mo to r i z e d p ros the s i se n joy z e ro hys t e re s i s a nd c re e p w i th a ve r y h igh re s i l - c on t ro l (H e c k a th om e , C , RESNA 12 th a nnua l C onfe r -ience , sensi t iv i ty , and dy na mi c resp ons e . 15 enc e , 1989, pp . 224225)T he K ru se n L im b Lo a d M on i to r i s a n i l l u s t r a t i ve Th e se r e s i s t i ve de v ic e s , how e ve r , a re unsa t i s fa c to ryp r io r a r t de v ic e . Th i s de v ic e is de sc r ibe d in C ra ik , R . fo r se ve ra l r e a sons . I l l u s t r a t i ve ly , t he r e spon se o f t he sea n d W a n n s t e d t , G . , Proceedings 2nd Conf Devices and resist iv e t ran sdu cer s i s no t l inear but i s substa nt ia l lySystems for the Disabled 1975 , 19 -24 . Th e c a pa c i t i ve e xpone n t i a l . U n l oa d e d re s i s t a nc e i s e f f e c t ive ly in f in it e ,t r a nsduc e r c ons i s t s o f t h re e l a ye r s o f c oppe r - Myla r

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5,449,002t e rn fo r mon i to r ing c r i t i c a l p re ssu re po in t s on pe r sonsw i t h d imin i she d se nsa t ion o f t he f e e t sho w n by G o -fo r th i n h i s 1987 U . S . Pa t . N o . 4,647 ,918 . In t he G o fo r thd i sc lo su re , r e s i s to r s a re p l a c e d unde r t he he e l , l a t e ra lp l a n t a r su r fa c e , me ta t a r sa l he a ds , a nd toe s o f t he pa - 5t i e n t . The in fo rma t ion s igna l s f rom e a c h o f t he se r e s i s to r s i s t r a nsm i t t e d to a po r t a b l e mic rop r oc e s so r . T h ec omple x i ty , c o s t , a nd fragihty o f t h i s a ppa ra tu s ma ke i tunsa t i s f a c to ry , how e ve r , fo r a pp l i c a t ion to l imb loa d inga f t e r o r th ope d ic p ro c e d u re o r fo r ga i t t r a in ing . 10Te c sc a n Inc . (B os ton , Ma ss . ) ha s de ve lope d a p re s su re ma pp ing sys t e m fo r ga i t a na ly s i s (Se nso rs , Ma y1991, pp . 21 -25 ) . i n w h ic h 960 re s i s t i ve e l e me n t s a rec o n t i n u o u s l y s a m p l e d b y a p e r s o n a l c o m p u t e r d u r i n ga mbu la t ion . G ra ph ic s o f e xc e ss ive l oc a l p re ssu re on the 15foot a re d isplayed in rea l t ime . A simi la r device also hasbe e n de ve lope d by Te c sc a n fo r de t e rmin ing g lu t e a l , o rb u t t o c k s p r e s s u r e c o n t o u r s . T h i s l a t t e r s y s t e m m a y b euse d fo r e va lua t ing se a t ing sy s t e ms . B o th o f t he se sy s t e ms , f rom the s t a ndpo in t o f a su i t a b l e b io fe e dba c k 20a p p a r a t u s i n a d y n a m i c en^vironment a re e xpe ns ive , l a c kdu ra b ih ty , a re f r a g i le a nd c omp le x .

HydraiiUc de v ic e s e a s i l y de t e rmine to t a l w e igh t a p phed to i r regular surfaces and, in th is respec t , a re s imi-

c on ta c t i s e s t a b l i she d be tw e e n the tw o d i sc s t o e ne rg i z ea buz zer . By adjust ing a se t sc re w on one d isk , thew e igh t a t w h ic h the buz z e r sounds a l so ma y be a d ju s t e d . Th i s de v ic e i s sub je c t t o me c ha n ic a l p rob le m s; i ti s d i f fi c u lt t o a d ju s t t he de v ic e t o t he t r i g ge r w e igh t ;a nd on ly one type o f shoe ( a c a s t boo t ) ma y be u se dw i th th i s a ppa ra tu s .O t h e r p h e n o m e n a a p p h e d t o b i o m e d i c a l f o r ce m e a su re me n t i nc lude s t r a in ga uge a nd p i e z oe l e c t r i c t e c h no log ie s . S t r a in ga uge s a re ma de o f c o i l s o f t h in h igh -resis tance wire or of meta l or s i l icon impressions tha ta re d if fu se d o r o the rw i se a pph e d to a subs t r a t e . B e c a usethe y e n joy a h igh l e ve l o f a c c u ra c y , t he se t r a nsduc e r sa re good fo r ga i t r e se a rc h . N e ve r the l e ss , t he y a l so a refragi le , expensive and consimie l a r g e a m o u n t s o f p o w e r .Fo r t he se r e a sons , de v ic e s o f t h i s na tu re a l so a re un -su i t e d fo r t he de ma nds o f da i ly t he ra pe u t i c u se . A dd i t i ona l ly , t he se de v ic e s e mi t lo^w po w e r s igna l s t ha t r e qu i re e x t e ns ive a mp l i f i c a t ion , a l a rge vo l imie , a c on t ro l l e d en-vironment a nd a re e xpe ns ive .

In s immia ry , w e igh t be a r ing b io fe e dba c k a ppa ra tu sa nd p roposa l s t ha t ha ve c ha ra c t e r i z e d the p r io r a r t a reunde s i r a b ly c omple x , e xpe ns ive , sub je c t t o f a i l u re , a ndla c k du ra b i l i t y . A l though fo rc e se ns i t i ve r e s i s to r s a reia r to capac i t ive de 'v ices. Ho'wever, by de f in it i on the s e 25 p romis ing fo r c e r t a in l im i t e d a ppU c a t ions , t he y a re sub -hyd ra u l i c de v ic e s me a su re the t o t a l w e ig h t by me a ns o f s t a n t i a l l y non - l ine a r i n e l e c t r i c a l r e spons e a nd ne e df lu id p re ssu re i n a c lo se d c ha m be r . A s a c onse que nc e , de d ic a t e d e l e c t r i c a l c i r c u i t s t ha t ge ne ra t e l i ne a r a ndhyd ra u l i c de v ic e s t e nd to be l a rge , he a v y , bu lky , t h i c k in t e g ra t e d o u tpu t s igna l s t ha t r e f l e c t t he me a su re do r r ig id . N e v e r the l e s s , hyd r a u l i c a nd c onc e p tua l ly s imi - w e ig h t . F o r l a rge , i r r e gu la r su r fa c e s a n array o f ma nyla r pne um a t i c sy s t e m s ha v e be e n a pp l i e d to l imb loa d 30 F SR 's mu s t be u se d . Th i s fu r the r i nc re a se s t he c omple x -de t e c t ion , g r ip s t r e ng th de t e c t ion , a nd se a t ing p re ssu resys t e ms .T w o d e v i c es f o r pro viding ob je c t ive a nd imme d ia t el imb loa d ing da t a f e e dba c k a re de sc r ibe d in S ipe , U .S .Pa t . No. 3 ,974,491 and Pfe i ffe r , U.S. Pa t . No. 3 ,791,375. 35B o th o f t he se de v ic e s e mp loy re se rvo i r s be low the he e la nd so l e . A pp l i e d -weight c o m p r e s s e s t h e s e r e s e r v o i r sa nd the fo rc e , o r w e ig h t i s mo n i to r e d by a t r a ns duc e r o nthe pa t i e n t ' s a nk le . A pa r t f rom the ne e d fo r a de d ic a t e dshoe , t he se t r a nsduc e r s a re d i f f i c u l t t o pu t on a nd t a ke 40o f f , a nd the he igh t a dde d to t he shoe to a c c ommoda tet h e s e de^vices ma y impe d e a mbu la t ion in a n indi^vidualw hose w a lk ing i s a l r e a dy impa i re d a nd poss ib ly unsa fe .HydrauUc de v ic e s fo r me a su re me n t o f g r ip s t r e ng tha re kno w n a s dyn a m om e te r s . T he s e de 'v i c e s a re l a rge 45and he av y and fl ie appl ied for ce is read d i rec t l y f rom ap re ssu re ga uge , w h ic h i s d if f ic u l t fo r t he pa t i e n t t o r e a d .D ue to t he se l im i t a t i ons , t he y a re no t de s igne d fo r u sedu r ing e xe rc i se a nd a re c e r t a in ly i na pp rop r i a t e fo r t hee lde r ly o r f ra il a r th r i t i c w h o w o u ld mos t be ne f i t f rom 50 o f a n ope n c e l l po lyu re tha ne foa m d ie l e c t r i c sa nd -

i t y a nd the c os t fo r t he sy s t e m a s w e l l a s t he c u r re n td ra in w h i l e , a t t he sa me t ime de c re a s ing du ra b i l i t y a ndbat te ry l i fe .C a pa c i t i ve t r a nsduc e r s , on the o the r ha nd a re i nhe r e n t ly l i ne a r a nd in t e g ra t e t he fo rc e i n fo rma t ion . C a pa c i t i ve t r a nsduc e r s fu r the r a re i nde pe nd e n t o f t he bo dya nd t r a nsduc e r c on tou rs . The se de v ic e s ne e d no t bec us tomiz e d a nd thus the y a re r e a d i ly i n t e rc ha nge da mong pa t i e n t s .O n th i s ba s i s , i t se e ms tha t c a pa c i t i ve t r a nsduc e r sshou ld h a ve the be s t po t e n t i a l fo r b io fe e dba c k ope ra t io nexcept for the fac t tha t no sui table d ie lec t r ic has beenident i f ied tha t wi l l permit the goa ls of s impU c i ty , lowc os t , r e l i a b ih ty , po r t a b i l i t y a nd low c u r re n t d ra in t o bea c h ie ve d in a c omme rc i a l de 'v i c e .

S U M M A R Y O F I N V E N T I O NT h e p r e s e n t i n v e n t i o n o v e r c o m e s t h e d i s a d v a n t a g e so f t he p r io r a r t . I t i s a c a pa c i t i ve t r a nsduc e r , c ons i s t i ng

g r ip s t r e ng the n ing .Pnetrmatic de v ic e s a l so ha ve be e n de ve lope d to me a su re p re ssu re s be ne a th bony p romine nc e s i n e va lua t ingw h e e l c h a i r s e a ts . B e c a u s e t h e s e p n e u m a t i c t r a n s d u c e r sare essent ia l ly f la ttened, mod if ied ba l lo ons , the i r s ize , 55sha pe a nd f r a g ih ty ma ke the m ina pp rop r i a t e fo r pe rma ne n t ly mon i to r ing the w e igh t o f a pa t i e n t on a w he e l c ha i r se a t a nd the y a re no t a da p ta b le t o t he -wide va r i e tyo f w he e lc ha i r a nd w he e lc ha i r c u sh ions now a va i l a b l e .O t h e r p h y s i c a l p h e n o m e n a h a v e b e e n e m p l o y e d ,a pa r t f rom the fou r me n t ione d a bove , t o p rov ide a me a su re o f t he phys i c a l p re ssu re a pphe d by a pa t i e n t t os o m e t h e r a p e u t i c o r p r o s t h e t i c d e v i c e . E x e m p l a r y o fth i s last g r o u p , t h e m e c h a n i c a l s w i t c h i n g d e v i c e , d e sc r ibe d in G ra d i sa r , U .S . Pa t . N o . 3 ,702 ,999 m e a su re sl imb loa d ing . Ea c h o f tw^osw i t c h e s ha s tw o me ta l d i sc sse pa ra t e d by a n O r ing . A s w e i gh t is a pp l i e d to t heto p d isk , the 0 r ing is com pres sed unt i l e lec t r ica l

60

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w i c h e d b e t w e e n t wo c ond uc to r s . Th i s foa m i s a ke yfe a tu re o f t h i s i nve n t ion . I t is u se d in e ve ry e mb od im e n t .I n m o s t e m b o d i m e n t s , t h e c o n d u c t o r s a r e w i r e m e s h ,s imi l a r i n a ppe a ra nc e to windo^w sc re e n .A s e c o n d un-ob^vious fea ture of th is invent ion is useo f c a rbon impre gna te d s i l i c one rubbe r (CISR) as thec o n d u c t o r s i n s o m e e m b o d i m e n t s . C I S R i s t h e m a t e r i a le m p loy e d in t r a nsc u ta ne ou s e l e c t r i c ne r ve s t imu la t ion( T E N S ) . I t h a s h i g h r es i s t an c e t o D C c u r r e n t . H o w e ve r , fo r me a su re me n t o f c a pa c i t a nc e i t a c t s a s a c on d u c t o r . E m b o d i m e n t s with C I S R h a v e r e m a r k a b l e p l i a b i l i t y a nd rugge dne ss .T he p re fe r re d po lyu re tha n e foa m i s c ha ra c t e r i z e d int e rms o f c he mis t ry , de ns i ty , f i rmne ss a nd morpho logy .C he mic a U y , po lyu re tha ne s a re fo rme d a s d i i soc ya na te s( h a v i n g t h e g e n e r a l structiureR N = = C = 0 ) re a c t w i thpo lyo l s ( a l c oho l s ) . D e ns i ty i sconmionly re fe r re d to a spou nds pe r c ub ic foo t , o r pcf . Th e p re fe r re d de ns i ty

Prov ided by PatentStorm h t t p : / / w w w . p a t e n t s t o r m . u s

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5,449,002 8range for the present invent ion is 5-50 pcf . Fi rmness, i sde f ine d a s t he c ompre s s ive fo rc e ( e xp re sse d a s pou ndspe r squa re i nc h , o r p s i ) r e qu i re d to c a use a 25% c omp re ss ion o f t he po lyu re tha ne foa m. (A de v ic e c a us ing a0 .2 i nc h /m inu te s t r a in r a t e is u se d ) . T he p re fe r re d f irm- 5ne ss r a nge fo r t he i n s t a n t i nve n t ion i s 0 .1 -100 p s i . M or pho log ic a l ly , t he foa m i s ma de up o f a p l e tho ra o f a p p rox im a te ly sphe r i c a l c e ll s . T he p re fe r re d a ve r a ge c e l ld i a me te r i s 50 -200 mic rons . C e l l s a re i n c ommunic a t ionth r ou gh a mu l t i t ud e o f po r e s ( t hus , ope n ce l l ) . Un im - 10pe de d a i r f l ow th rough the foa m subs t a nc e he lp s e s t a b l ish resi l ience . On formal test ing there i s a loss of 5%th ic kne ss o r l ess on a n A S T M 1667 c ompre ss ion se t a t73 de g re e s F . Foa ms o f t h i s t ype a re p re fe ra b ly ma nuf a c t u r e d b y R o g e r s C o r p . , P o r o n M a t e r i a l s D i v i s i o n , 15E a s t W o o d s t o c k , C o n n e c t i c u t .T he p re fe r re d po ly u re th a ne foa m o f th i s c l a ss i s ma r k e t e d a s P P T ( m n e m o n i c f o r P e r s o n a l P r o t e c t i v eT e c h n o l o g y ) , a t r a d e m a r k o f L a n g e r B i o m e d i c a lG r ou p . Th i s ope n c e ll , h igh de ns i ty , m ic ro c e l lu l a r po ly - 20u re tha ne foa m ha s a n a ve ra ge po re s i z e o f 100 mic rons ,den si ty of 20 pcf, and f irmness of 1 0 3 psi a t 25 %c ompre ss ion . Po lyu re tha ne foa ms o f t he p re se n t i nve n t i on a re p re fe ra b ly c ons t ruc t e d w i th P P T (g) d i e l e c t r i c .Thus , i n t he d i sc uss ion be low ope n cell p o l y u r e t h a n e 2 5f o a m is r e f e r r e d t o a s P P T . H o w e v e r , a n y m e m b e r o fthe sa me c l a ss (w i th the a bove de sc r ibe d c ompone n t s )m a y b e u s e d w h e r e a p p r o p r i a t e ) . P P T (un l ike o the ropen-ce l l foams) has been wel l -known in the f ie ld ofre ha b i l i t a t i on fo r se ve ra l ye a r s . The c onv e n t io na l a pp l i - 30c a t ion i s a s foa m pa d d ing fo r p ro t e c t iv e u se in shoe s .A l though w e l l know n in the f i e ld o f r e ha b i l i t a t i on fo rse ve ra l ye a r s , no one ha s t ho ug h t t o a pp ly i t t o so lve th ew e igh t be a r ing d i l e mma . H ow e ve r , t he sa me fe a tu re stha t ma ke i t a good p ro t e c t ive foa m c ush ion w i th e xc e l - 35lent e ne rgy a bso rp t ive p rope r t i e s a l so ma ke i t t he be s ta va i l a b l e c a pa c i t i ve d i e l e c t r i c . Th e se inc lude un su r pa sse d re s i l i e nc y to bo th s t a t i c a nd dyna mic loa d ing ,a nd l i ne a r i t y w i th c ompre ss ion .P P T @ w a s found supe r io r t o ne op re ne a nd po iye th - 40ylene foa ms in r e s i l i e nc y on e x t e ns ive dyna mic t e s t i ng(B rodsky , e t . al . . Foot and A nkle V o l . 9 , D e c e m b e r ,1988, p p . 1 1 1- 1 1 6) . P P T s h o w e d n o lo s s o f t h ic k n e s sfo r 10 ,000 c yc l e s o f c om pre ss ion o r she a r c omp re ss ion .(10 ,000 c yc l e s c o r re sp ond s to 9 hou rs o f w a lk ing a t 45n o r m a l c a d e n c e ) , w h e r e a s N e o p r e n e s h o w e d a 5 - 1 5 %loss o f t h ic kne ss , a nd po lye th y le ne foa m 15 to 50 % losso f t h i c k n e s s . D e v i c e s m a d e w i t h P P T s h o u l d t h u sl a s t a ve ry long t ime . Fu r the r , one e xpe c t s de v ic e s ma dew i t h P P T b e fa r m o r e d u r a b l e th a n p o l y e t h y l e n e 50( K r u s e n M o n i t o r ) o r n e o p r e n e ( M i y a z a k e a n d I s h i d ade v ic e ) .F u r t h e r m o r e , t e s t in g re v e a l s P P T t o h a v e f ar b e t t e r r e s i l i e nc y to s t a t i c l oa d ing tha n po lye thy le ne a ndne op re ne foa ms . A squa re o f PPT ma y be p l a c e d unde r 55a desk leg for a week and re turn immedia te ly to i t so r i g i n a l s h a p e . H o w e v e r , n e o p r e n e o r p o l y e t h y l e n ef o a m s w o u l d r e m a i n p e r m a n e n t l y c o m p r e s s e d .T h e s e c o n d a d v a n t a g e o f P P T i s i m p r o v e d l i n e ar i tyw i t h c ompre ss ion . I t is fo r tu i tous bu t g ra t i fy ing tha t t h i s 60t ra ns duc e r i s l i ne a r w i th i n na r r ow l imi t s f rom z e r o t o7 5 % c omp re ss ion o f t he d i e l e c t r i c . T he ra n ge o f l ine a r i t y o f p re ssu re t o c omp re ss ion i s w id e r t ha n the o th e rtw o foam ma te r i a l s . Th us , de fo rm e d fe e t t r a ns fe r r ingh igh loc a l a re a s o f c om pre ss io n shou ld y i e ld e qu iva l e n t 65c a pa c i t a nc e c ha nge to a more sp re a d ou t l oa d . Th i s i s ac l e a r i m p r o v e m e n t o v e r t h e d e v i c e d e s c r i b e d b y M i y a z a ke a nd I sh ida .

A dd i t i ona l ly , c re e p i s impe rc e p t ib l e w i th g re a t e rtha n 75% c ompre ss ion fo r e x t e nde d pe r iods . Th i s i s i nc on t ra s t t o ne op re ne a nd po lye thy le ne foa ms , w h ic hshow s ign i f i c a n t c re e p a t t h i s l e ve l o f c ompre ss ion .Th us , t h i s l a mina t e i s ve r y p rom is ing a s ba s i s fo r ava r i e ty o f w e igh t b io fe e dba c k de v ic e s i n t he c l i n i c a lse t t i ng . Se ve n spe c i f i c e mbod ime n t s a re i n t roduc e d int h e f o l l o w i n g p a r a g r a p h s :A . P a r t i a l W e i g h t B e a r i n g O r C a s t B o o t E m b o d i m e n t

T he pu rp ose o f t he c a s t boo t e mbo d im e n t i s t o imp r o v e c o m p l i a n c e w i t h t o e t o u c h o r p a r t i a l w^eightbe a r ing o rde r s a f t e r bone su rge ry on the h ip o r l e g . Th i sa ssu re s t he sho r t e s t , sa fe s t c ou rse o f pos t -ope ra t ive r e ha b i l i t a t i on . A c a s t boo t i s a n ove r s i z e d , ope n , c a nva sshoe f r e que n t ly w or n by suc h pa t i e n t s du r in g da i lya mbu la t ion t r a in ing . A th in e mbod ime n t ma y f i t i n s ide ac a s t b o o t . I n t h e p r e f e r r e d e m b o d i m e n t t h e c o n d u c t i v el a y e r i s w i r e s c r e e n . H o w e v e r , c a r b o n i m p r e g n a t e ds i l i c one rubbe r ma y be u se d .B . S h o e E m b o d i m e n t

The shoe e mbod ime n t i s i n t e nde d fo r a pa t i e n t -witha n in se nsa t e e x t re mi ty . The well k n o w n w o r k o fB a c h-Y -R i t a sugge s t s t ha t e l e c t r i c a l ly a ugme n t ing se n so ry f e e dba c k he lp s suc h a pa t i e n t re-leam a nd ma in t a insa fe , func t iona l a mbu la t ion . C ond i t i ons tha t l e a d toin se nsa t e e x t re mi t i e s i nc lude pe r iphe ra l ne u ropa thy(e .g . , f rom d ia be t e s ) o r t r a uma t i c sp ina l c o rd in ju ry . Ase c o nda r y be ne fi t ma y be r e du c t ion in foo t u l c e ra t iona nd de fo rmi t i e s . Ma ny p ros the t i c w e a re r s w ou ld be ne f i tf rom se nso ry f e e dba c k , e spe c i a l l y t he ma ny a mpu te e sw i th d i a be t e s .Phys i c a l ly , t he e mbod ime n t r e se mble s a n inne r - so l ea nd i s c onc e a l e d w ithin a shoe . Th i s de v ic e i s be s t e mp loye d w he re c osmose s a nd h igh l e ve l func t ion ing a repar am ou nt . Us e is for an indef in i te per io d due to ac h ron ic c ond i t i on . Low c os t a nd long l i f e a re l i ke ly t oc re a t e a ma rke t fo r t h i s e mbod ime n t . In t he p re fe r re de m b o d i m e n t t h e c o n d u c t i v e l a y e r i sw ire sc r e en . H o w e ve r , c a rbon impre gna te d s i l i c one rubbe r ma y be u se d .C . A n k l e B r a c e E m b o d i m e n t

C h i ld re n w ith d ip l e g i c c e re b ra l pa l sy t e nd to a m bul a t e w i t h a n e qu inu s ( i .e . , dow n-w a rd po in t in g ) a nk le dueto poo r c e re b ra l p roc e ss ing o f mo to r i n fo rma t ion . The ya dop t no rma l he e l s t r i ke on ly w he n c ons t a n t ly r e minde d ( i . e . , c ue d ) . Th i s be ha v io r pe r s i s t s de sp i t e u se o fa n A F O (a n k le foo t o r thos i s , o r a nk le b ra c e ) , spe c i f i c a l ly de s igne d to p re ve n t i t . A n e mbod ime n t i s de sc r ibe d w hic h a l l ow s e l e c t ron ic c u ing o f he e l s t r i ke . I ti s de s igne d to be u se d w i th a n A F O . P re v iou s w or k(Se e ge r , B . R . , A rc h ive s o f Phys i c a l Me d ic in e a nd R e ha b i l i t a t i on , 56 : 237 -240 ) sugge s t s suc h a de v i c e w o u ldimprove a mbu la t ion in t he se c h i ld re n . In t he p re fe r re de m b o d i m e n t t h e c o n d u c t i v e l a y e r i s w i r e s c r e e n . H o w e v e r , c a r b o n i m p r e g n a t e d sUicone rubbe r ma y be u se d .D . G r i p S t r e n g th E m b o d i m e n t

I som e t r i c s t r e n g the n ing ( i .e . , e xe rc i se o f a mu sc l ew i t hou t c ha n ge o f i t s l e ng th ) is p re fe r re d in t r e a tm e n t o fa r th r i t i s a nd t e nd in i t i s o f t he ha nd . Th i s i s be c a use jo in ta n d t e n d o n m o v e m e n t t e n d s t o ^vorsen in f l a mma t ion .T h e g r i p s t r e n g t h e m b o d i m e n t m e a s u r e s g r i p p r e s s u r ew i t h o u t p e r c e p t i b l e m o v e m e n t o f t h e d e v i c e . T h i s i sdue to t he c ha ra c t e r i s t i c s o f t he po lyu re th a ne d i e l e c t r i cin t he c a pa c i t i v e t r a nsdu c e r . I t is de s igne d to r e p l a c e theh e a v y a n d c u m b e r s o m e d y n a m o m e t e r t h a t w o r k s o n

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5,449,002 10hydraidic p re ssu re . The p re se n t i nve n t ion i s sma l l a ndl igh tw e igh t , a n d thus ma y be u se d by e ve n a w e a k , f r ai lpa t i e n t w i thou t supe rv i s ion . B y g iv ing c on t inuous f e e d ba c k a bou t fo rc e a pp l i e d , i t w i l l improve mo t iva t ionand qua l i ty of exerc ise in these pa t ients . I t may a lso be 5use d fo r s t r e ng the n ing a nd e de ma c on t ro l i n t he w e a kha nd o f s t roke pa t i e n t s , t he ha nd tha t t e nds t o be ne g l e c t e d ( i .e . , i gno re d ) du e to t he c ogn i t i ve e f fe ct s o f t h es t roke . La s t ly , suc h a de v ic e c ou ld be u se d by the l a ypubUc for exerc ise of gr ip . 10

E . AxiUary C r u t c h E m b o d i m e n tA x i l l a ry c ru t c he s a re f r e que n t ly u se d by pa t i e n t s t ha ta re pa r t i a l w e ig h t be a r ing on one l e g . Th e y t r a nsmi tw e igh t t h rough a n a rm a nd ha nd to t he b ra c e in s t e a d o f ^^t h r o u g h t h e le g . H o w e v e r , i f t h e c r u t c h e s a r e u s e dinc o r re c t ly , t he b ra c h ia l p l e xus ma y be in ju re d . (Theb ra c h ia l p l e xus i s a bund le o f ne rve s pa ss ing th ro ug h thea x i ll a t o c on t ro l a rm mo ve m e n t a nd se nsa t ion ) . Mon thso f pa in , w e a kne ss a nd nimibness ma y re su l t f rom th i sn o t u n c o m m o n i n j u r y . S t r a i n g a u g e s n o r m a l l y retaU for$500.00 on up, so this devi ce is no t very cost -e ffec t ive .H o w e v e r , t h e p r e s e n t i n v e n t i o n h a s a s i m p l e c o n s t r u c t ion tha t m ay enab le i ts rou t in e use as a sa fe ty fea turewi thin axi l la ry c ru tches a t re la t ive ly low cost .

20

25F . W h e e l c h a i r E m b o d i m e n t

A n ine xpe ns ive , du ra b le me a ns to de t e c t p re ssu re ona whee lcha ir sea t -would ha ve ma ny use s . Pa ra p le g i c s -_a nd pa t i e n t s w i th sp ina b if i da, i n se nsa t e be low t he w a i s t ,w^ould benefi t f rom a devi ce to cu e we ig ht shi f t ing a tr e gu la r i n t e rva l s . I t m igh t r e duc e inc ide nc e o f sa c ra lpres sure -u lcers in these popul a t io ns. Ma lam ent , e t . a l .(A rc h ive s o f Phys i c a l Me d ic ine a nd R e ha b i l i t a t i on , 56 : ^5161-165 ) de mons t ra t e d suc h be ha v io r s c ou ld be l e a rne db y u s e of b i o f e e d ba c k . H o w e v e r , b u l k y h y d r a u l i c d e v i c e s o r e xpe ns ive s t r a in ga uge s ha ve be e n u se d in t hepa s t fo r mon i to r ing . O the r de^vices a re ba se d onsw i t c he s , -w h ic h do no t a l l ow the pa t i e n t t o i e a m p ro - 4Qg r e s s i v e w e i g h t r e d u c t i o n d u r i n g t h e -weight shif t . T h ew h e e lc h a i r e mbod ime n t is unob t r u s ive , r e l a t i ve ly i ne x pe ns ive , r e a d i ly a da p ta b le t o a ny se a t de s ign , u se s on lys imp le e l e c t ron ic s , a nd mon i to r s g ra da t ions o f p re ssu re .Suc h a de v ic e c ou ld a l so he lp r e duc e f a l l s due to 45unassisted a t tempts to r i se out of a -whee lcha ir on thepa r t o f pa t i e n t s -w i th de m e n t i a . A n una ss i s t e d a t t e m p tw o u ld a c t iva t e a n a l a rm . I t i s c u r re n t ly ve r y im por t a n tin ntirsing home p ra c t i c e t o u se min ima l r e s t r a in t ( e .g . ,w r i s t o r w a i s t s t r a ps ) . Thus , t h i s de v ic e c ou ld r e duc e 50falls, a c o m m o n c a u s e o f m o r b i d i t y i n n u r s i n g h o m e s ,a nd a t t he sa me t ime min imiz e phys i c a l r e s t r a in t .In t e rms o f r e ha b i l i t a t i on , ma ny pa t i e n t s imme d ia t e lya f t e r s t roke a re impu l s ive a nd unsa fe . P re ss u re d e t e c t ionc ou ld e l e c t ron ic a l ly c ue the m to lock w he e lc ha i r b ra ke s 55p r io r t o r i s ing , a nd thus p romote sa fe ty a w a re ne ss a ndre duc e ne e d le ss i o ju ry . A H the se i s sue s c ou ld be suc c e ss fu l ly a dd re sse d by a w he e lc ha i r e mbod ime n t o f myinve n t ion . 60G . P r e s s u r e P a d E m b o d i m e n t

These consist of se ts of c i rcula r , e l l ip t ica l or rec tangu la r l a mina t e s o f c a rbon impre gna te d s i l i c one rubbe ra n d P P T . T h e y w o u l d b e u s e d f o r i s o m e t r i c s t r e n g t ht ra in ing ( i . e ., o the r t ha n g r ip s t r e ng th ) in t he phy s i c a l o r 65oc c upa t iona l t he ra py gym. I t ma y in sp i re c re a t iv i tywi thin these d isc ip l ines and be the source of fur thera pp l i c a t ions .

O B J E C T S O F T H E P R E S E N T I N V E N T I O NThus , se ve ra l ob j e c t s a nd a dva n ta ge s o f t he p re se n tinve n t ion inc lude :1 ) F l e x ib i l i t y , suc h tha t i t ma y be inc o rpo r a t e d in tow e igh t me a su r ing shoe s , c a s t boo t s , w he e lc ha i r s , de v i c e s t o me a su re g r ip o r p inc h , o r d i r e c t ly i nc o rpo ra t e d-within or thot ics .2 ) L ow p ro j e c t e d c os t due to s imph c i ty o f c ons t ruc tion.3 ) U no b t ru s ive ne ss ( i t c a n be ma d e l e ss t ha n 0 .16 c m .o r J of an inch thick) .4 ) D u ra b ih ty , a s t he on ly mov ing pa r t i s t he c om p re ss ib l e p l a s t i c foa m, w h ic h re tu rns t o i t s o r ig ina lth i c kne ss a f t e r l oa d ing a f t e r e ve n mon ths o f c on t inuoususe.5) S imp l i c i t y o f p roc e ss ing . W e ig h t i s i n t e g ra t e d ov e ra ny ra nge de s i r e d to ob ta in a t o t a l w e ig h t .6 ) Inhe re n t ly l i ne a r o u tpu t .7 ) S imp l i c i t y o f e l e c t ron ic p roc e ss ing due to 5 a nd8 ) A c c u ra c y to t he e x t e n t ne c e ssa ry in a c l i n i c a l se t t i ng .9 ) A b i l i t y t o ob ta in w e igh t a pp l i e d th r ou gh l a rg e ,i r r e gu la r su r fa c e s a s e a s i l y a s t h rough sma l l , r e gu la r

one s : Th a t i s , a b i l i t y t o i n t e g ra t e w e igh t ov e r a re a .B e c a u s e of t h e s e a d v a n t a g e s m a n y e m b o d i m e n t s s u g ge s t t he mse lve s :1 ) Fo o t w e i gh t be a r ing fe e dba c ka ) a f t e r o r tho pe d ic p roc e du r e s o r f r ac t iu res .b) a f te r s t roke to fac ihta te re - learning of weight shi f t i ng , t he n a mbu la t ion .c ) f a c ih t a t e pa ra p le g i c a mbu la t ion .d ) f a c i l i t a t e a mbu la t ion o f a mpu te e s w i th p ros the t i cl imbs.2 ) U p pe r e x t re mi ty f e e dba c k , su c h a s t o p rov ide b io fe e dba c k o r g r ip o r p inc h s t r e ng th .3 ) A p phc a t ion d i r e c t ly w i th in o r tho t i c s .a ) c o r re c t t e nde nc y tow a rds ga i t de v ia t ions i n c e re b ra l pa l sy pa t i e n t s .4) Appl ica t ion -wi thin assis t devices, such as c ru tches.5 ) W h e e lc h a i r se a t p re ssu re f e e dba c k .a ) e lec t ronic cuing to weight shi f t in sp ina l in juredpa t i e n t s p rone to p re ssu re u l c e r s .b) a la rm to nursing sta ff tha t pa t ients on fa l l precaut ions hav e imp ulsiv e ly r isen from the whe e lc ha i r .c ) cue pa t ien t to lock -whee lcha ir brea ks before r is ing .6 ) F l e x ib l e p re s su re pa ds w i th ge ne ra l u se -w ith inthe phys i c a l o r oc c upa t iona l gym, fo r musc l es t r e n g t h e n i n g o r e n d u r a n c e p r o g r a m s .O the r ob je c t s a nd fe a tu re s o f t he p re se n t i nve n t ion-w Ul be c om e a pp a re n t f rom t he foUo-wing de t a i l e d de sc r ip t ion c ons ide re d in c onne c t ion -with t h e a c c o m p a ny ing d ra -w ings . I t i s unde r s tood , how e ve r , t ha t t hed ra -w ings a re de s igne d fo r pu rpose s o f iUustration on ly ,and not as a def in i t ion of the l imi ts of the invent ion for-w hic h re fe re nc e shou ld be ma de to t he a ppe nd ingc la ims .

B R I E F D E S C R I P T I O N O F T H E F I G U R E SF IG . 1 i s a e n l a rg e d pe r sp e c t ive v i e w o f t he c a s t boo te mbod ime n t -w i th in a c a s t boo t a nd a ssoc i a t e d e l e c t ron i c s modu le ;F IG . 2 i s a t op a nd s ide p l a n v i e w o f t he c a s t boo te m b o d i m e n t ;F IG . 3 i s a n e xp lode d pe r spe c t ive v i e w o f t he c a s tb o o t e m b o d i m e n t ;F IG . 4 i s a g ra ph o f w e igh t ve r sus c a pa c i t a nc e fo r t h ec a s t b o o t e m b o d i m e n t ;

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11 5,449,002 12F IG . 5 i s a pe r spe c t ive v i e w o f t he shoe e mb od im e n tbe ing used in a typica l appl ica t ion;F IG . 6 i s a t op a nd s ide p l a n v i e w o f t he shoe e m bod i me n t ;F IG . 7 i s a n e xp lode d pe r spe c t ive v i e w o f t he shoe 5e m b o d i m e n t ;F IG . 8 i s a n e xp lode d pe r s pe c t iv e v i e w o f t he a n k leb r a c e e m b o d i m e n t ;F IG . 9 i s a n e xp lode d pe r spe c t ive v i e -w o f t he a nk leb ra c e e mb od ime n t ; 10F IG . 10 i s a p l a n v i e w o f t he g r ip s t r e ng th e mb od i me n t be ing u se d in a huma n ha nd ;F IG . 11 i s a pe r sp e c t ive v i e w o f t he g r ip s t r e ng t he m b o d i m e n t o u t s i d e t h e h a n d ;F IG . 12 i s a n e xp lode d pe r spe c t ive v i e w o f t he g r ip 15s t r e n g t h e m b o d i m e n t ;F IG . 13 is a n a f ron t e l e va t ion o f a n a x il l a ry c ru t c ha nd a x i l l a ry c ru t c h e mbod ime n t ;F IG . 14 i s a n e xp lode d pe r spe c t ive v i e w o f t he a x i l l a r y c r u t c h e m b o d i m e n t w i t h i n t h e t o p o f t h e c r u t c h ; 20F IG . 15 i s a n e xp lode d pe r spe c t ive v i e w o f t he ax i l l a r y c r u t c h e m b o d i m e n t itself;F IG . 16 i s a n pe r sp e c t ive v i e w o f a w he e lc ha i r w i ththe w he e lc ha i r e mbod ime n t w i th in the se a t ;F IG . 17 i s a t op a nd s ide p l a n v i e w o f t he w he e lc h a i r 25e m b o d i m e n t ;F IG . 18 i s a n e xp lod e d pe r sp e c t ive v i e w o f t hew h e e l c h a i r e m b o d i m e n t ;F IG . 19 i s a pe r spe c t ive v i e w o f t he p re ssu re pa de m b o d i m e n t ; a n d QFIG . 20 i s a n e xp lode d pe r spe c t ive v i e w o f t he p re s s u r e p a d e m b o d i m e n t .

D E T A I L E D D E S C R I P T I O N O F T H EP R E F E R R E D E M B O D I M E N T SA . C a s t B o o t B o d i m e n t 35

T he c a s t bo o t e mbo d ime n t i s i l l u s t r a t e d in F IG S . 1 -4 .F I G S . 1 a ffo rds a n ove rv i e w o f t he de v ic e . Th e c a s tbo ot (52) i s pre fe rably an overs ized ca nv as shoe -wi th anopen upper surface , and fastens over the foot or cast 40w i th a V e lc ro s t r a p (53 ) . A l s o , i t p ro -v ide s suppo r ta nd p ro t e c t ion to t he pa t i e n t ' s foo t .T he w e igh t de t e c t ing e l e me n t (50 ) s i t s on the up pe rsu r fa c e o f t he c a s t boo t . I t i s p re fe ra b ly ve ry simUar insha pe to t h i s p l a t fo rm, a nd no t pe rma ne n t ly g lue d o r 45fastened to i t . As such, i t i s easi ly insta l led and removedby the phys i c a l t he ra p i s t . The de v ic e c onne c t s t o a TALre(62) , the n to a n e l e c t ron ic modu le (64 ) p l a c e d on thec a s t boo t , be l t , poc ke t o r o the r c onve n ie n t p l a c e on thepa t i ent by mean s of a c l ip (82) . Pref e rab ly , a t t ach ed to 50the e l e c t ron ic s m odu le 64 i s a n a d ju s tme n t kno b (80 ) ,a nd a n on / o f f sw i t c h (90 ) . A dd i t i ona l ly , t he re i s p re fe ra b ly a p i e z oe l e c t r i c buz z e r w i th in modu le 64 (no ts h o w n ) .T he g ene ra l s ize and s hape of the de vic e is bes t 55show n w i th r e fe re nc e to F IG . 2 -w h ic h show s top a ndside v ie ws . De vi ce 50 is pre fe rab ly f lat , p lanar , f lexib lea nd re c t a n gu la r -w ith rou nde d e nds . Fo r a 'me d iu m ' c a s tboo t , i t i s p re fe ra b ly a ma x im um o f 9 .5 c m. w i de a t t heforefoo t (54) , tape r ing to 8 .5 cm w ide a t the hind foo t 60(56) . A dd i t i on a l ly , i t is p re fe ra b ly 24 .5 c m. l ong a nd 0 .3c m (J inc h) t h i c k .T he m e th od o f f a b r i c a t ion i s be s t de sc r ibe d w i t hre fe re nc e t o F I G . 3 . I t p re fe ra b ly c ons i s t s o f f ive l a ye r s .T he to p l a ye r (66 ) i s t h in rubbe r . T he ne x t l a ye r dow n 65(68) i s s tee l mesh. The per imeter of th is layer (69) i sp re fe ra b ly r e c e ss e d 0 .7 c m f rom the pe r im e te r o f ove ra l lde v ic e (73 ). M e sh a re a a nd ga ug e a re p re fe ra b ly s imi l a r

to c onve n t iona l -w indow sc re e n . Pos t e r io r ly , aTA ire (c onn e c t s w i th the me s h , a nd is p re fe ra b ly so lde re d 2c m . f r o m o n e c o m e r .B e lo w the me s h is a l a ye r o f po lyu re tha n e foa m, a sp r e v i o u s l y c h a r a c t e r i z e d , a n d p r e f e r ab l y P P T p o l y u re t ha n e foa m (72 ) , p re fe ra b ly 0.16 c m. (1 /1 6 inc h)th i c k . B e low th e PP T i s a no the r l a ye r o f s t e e l me sh(74) , subs t a n t i a l l y i de n t i c a l t o i t e m 68 . H o w e ve r , t hew i r e (75) p re fe ra b ly c onn e c t s 2 c m f rom th e o the r r e a rc ome r o f t he me sh . Thus , t he so lde r po in t s o f t he w i re sa re no t d i r e c t ly be ne a th e a c h o the r . B e low th i s i s t hef ina l laye r (78) , rub ber sh ee t essent ia l ly ident ica l to i tem66.A l l pa r t s a re p re fe ra b ly g lue d toge the r -w i th C on ta c tSp ra y A dhe s ive (U .S . Pa t . N o . 4 ,401 ,272 , 3M C ompa ny , S t . Pa u l , Minn . ) . Th i s ne op re ne -ba se d p roduc tbonds w e l l t o rubbe r , p l a s t i c foa m a nd me ta l . The f ivel a ye r s t hus fo rm a s t ron g , bu t f le xibl e i n t e rc on ne c t in gbond . Th i s f a c i li t a te s p ro l ong e d c l i n i c a l u se w i tho u t l o sso f p rope r t i e s .T he c a pa c i t i ve t r a nsdu c e r i s c re a t e d w h e n the de nsepo lyu re tha ne foa m (72 ) i s p l a c e d be t -w e e n me ta l p l a t e s(68 and 74) . As weight i s appl ied the foam is comp re sse d , de c re a s ing in t e r -p l a t e d i s t a nc e a nd inc re a s ingc a pa c i t a nc e . C onve rse ly , a s t he -w e igh t i s r e move d thein t e r -p l a t e d i s t a nc e a nd c a pa c i t a nc e r e tu rn to t he i r o r ig ina l va lue s . To de mons t ra t e bo th s t a b l e ba se l ine a ndl ine a r i t y , a c a s t boo t e mb od im e n t o f t he a bo ve spe c i fi c a t ions -was tested for i t s pres sur e-ca pac i tan ce prof i le .F IG . 4 i s a g ra ph de sc r ib ing the se r e su l t s . Ze ro to 160lbs o f w e igh t w e re a pp l i e d ov e r 5 a re a s o f w e igh t a pp l i ca t ion: 9 , 16 , 30 .2 and 40.2 cm^. (For re fe rence , the a reaof the av era ge ad ul t gre a t toe is abou t 6 cm^, hee l 30c m ^ , and forefoot 45 cm^ ) . C le a r ly , a h ig h de g re e o fl i ne a r i t y i s de m ons t r a t e d o ve r a w id e r a ng e o f c omp re s sion of the foam.

In a c onve n t iona l ma nne r , e l e c t ron ic s modu le (64 )c onve r t s c a pa c i t a nc e l i ne a r ly t o vo l t a ge . O f no te , t opp la t e 68 i s c onn e c t e d to g rou nd to l a rge ly n e u t ra l i z es t r a y c a pa c i t a nc e o f t he sub je c t f rom a f fe c t ing th i s s ig na l . Th i s vo l t a g e i s i n t e rna l ly c om pa re d -w i th a t r i gge rvo l t a ge p re fe ra b ly se t by kn ob 80 . Th i s knob i s se t i ncon junc t ion -wi th p la c ing th e pa t ient 's foot on a sca lep r io r t o a mbu la t ion . W he n -w e igh t e xc e e ds th i s p re se tt r i gge r a p i e z oe l e c t r i c buz z e r >A ithin the e l e c t ron ic smo du le p rov id e s f e e dba c k to t he pa t i e n t a nd phy s i c a lthe ra p i s t . In t h i s ma nne r t he pa t i e n t is i n fo rm e d a bou ttoe t ouc h , a nd pa r t i a l o r fu l l -weight be a r ing on th eaffec ted leg .

B . S h o e E m b o d i m e n tThe shoe e mbod ime n t i n a t yp i c a l a pp l i c a t ion i s i l l u s t r a t e d in F IG S . 5 -7 . In F IG . 5 a pa ra p le g i c is p ra c t i c ing

re c ip roc a l ga i t by \yeight shif t ing be t -ween extremit iesw he n bo th l e gs a re a na e s the t i c . T ra nsduc e r (100 ) i sp re fe ra b ly be ne a th the i n l a y o f a n o r thope d ic ox fo rdshoe on the r ight foot . Wires (114, 117) extend to thew a i s t on the r i gh t s ide w he re e l e c t ron ic modu le (128 ) i shoo ke d o n to the be l t . Th e r e is a s imi l a r c on f igu ra t ion onthe le f t s ide (not shoTA'n). T h e e lec t ron ics m od ul e iss imi l a r i n s t a t i c de s ign to t he c a s t boo t modu le , a nd ha sa t r i gge r mode , a nd on /o f f sw i t c h . In s ide , t he re i s asma l l v ib ra t ing mo to r t ha t impa r t s v ib ra to ry f e e dba c kto the pa t ient . A -wire less design could a lso be employed( n o t s h o w n ) . T h i s w o u l d f u r t h e r i m p r o v e c o s m o s e s .

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13 5,449,002 14The sha pe a nd th i c kne ss o f t he shoe e mbod ime n t i sbe s t niustiated w i t h r e fe re nc e to F I G . 6. T he de v ic e i spref erab ly thin , p lanar , f lexib le a nd substan t ia l ly f la t.T he fa b r i c a t ion o f t h i s de v ic e i s be s t de sc r ibe d w i threfer ence to F IG . 7 . I t pre fe rably co nsists of five layers . 5The se a re f rom top to bo t tom, gum rubbe r uppe r p i e c e(104) , top layer of s tee l mesh (106) , layer of PPT (108) ,bo t tom l a y e r o f s t e e l me sh (110 ) , a nd gu m rubb e r b o t tom p ie c e (111 ) . S t e e l me sh l a ye r s 106 a nd 110 a re prefe ra b ly r e c e sse d 0 .7 c m in s ide the pe r im e te r o f t he ove r - 10all de v ic e . S t e e l me sh top p l a t e (106 )coimects to a w i re(114) near the f ront of a rch (112) . Simila r ly , s tee l meshbo t tom p la t e (110 ) c on ne c t s t o a w i re (117 ) ne a r t he r e a ro f a rc h 112 . Th e se tw o w i re s c onn e c t t o e l e c t ro n ic smo du le (128) . 15T h e c a h b r a t i o n a n d o p e r a t i o n o f t h e s h o e e m b o d i me n t is s imi l a r t o t he c a s t boo t e mb od im e n t . H o w e ve r ,t he f e e dba c k i s p re fe ra b ly t a c t i l e i n s t e a d o f a ud i to r y .T he ra t i on a l e is t ha t t he a ud ib l e a l a rm m a y be d i s t r a c t ing an d embarr assi ng for a hig hly func t ion ing pa t ie nt in 20a w ork o r soc i a l se t t i ng . C a hb ra t ion o f t r i gge r l e ve l i sdone by the pa t i e n t by se t t i ng a t h re sho ld in c on junc t ion -wi th put t ing the foot on a sca le , and varying t r iggera d ju s tme n t kn ob . V ib ra t ion in t e ns i ty i s a l l o r n on e

a bove th i s t h re sho ld . A l t e rna t ive ly , i t c a n be w i re d to 25c on t inuous ly i nc re a se i n i n t e ns i ty -w i th w e igh t i nc re a sea bo ve a t h re sh o ld . Th e e l e c t ron ic de s ign o f t h i s de v ic ei s c onve n t iona l . In p re l imina ry s tud ie s a n a c t ive a du l tma le w ore th i s de v ic e fo r se ve ra l hou rs . A s t a b l e ba se l i ne c a pa c i t a nc e , a nd s t a b l e c a pa c i t a nc e inc re a se pe r 30u n i t w e i g h t i n c re a s e , w e r e n o t e d t h r o u g h o u t t h e e x p e r i m e n t .C . A n k l e B r a c e E m b o d i m e n t

a c e re b ra l pa l sy pa t i e n t l e a rn no rma l he e l s t r i ke du r inggait .D . G r i p S t r e n g t h D e t e c t o r E m b o d i m e n t

F I G S . 10 -12 re fe r t o t he g r ip s t r e ng th e mbod ime n t .F IG . 10 i l l u s t r a t e s t he i some t r i c g r ip s t r e ng th de t e c to re mb od im e n t (200 ) i n u se . I t is p re fe ra b ly c y l ind r i c a l o fsuc h d ime ns ions a s t o f i t snug ly in s ide the c l e nc he da du l t hum a n ha n d (202 ) . A n e l e c t ron ic s mod u le (252 ) i sp re fe ra b ly inc o rpo ra t e d in s ide the c y l ind r i c a l t r a ns duc e r . Thre sho ld s t r e n g th a d ju s tme n t kn ob (254 ) ha s abu i l t - i n on /o f f s -w i t c h . Thre sho ld s t r e ng th c a n be se tp re fe ra b ly f rom 0 to 60 lb s on th i s e mbod ime n t u s ingp r e s e tnimierical se t t i ngs (256 ) . F IG . 11 sho w s th e ge n e ra l c on f igu ra t ion o f t he de v ic e . I t i s p re fe ra b ly 12 c m(4.25 inches) long and 3 .7 cm (1 .5 inches) in d iameter .

C o n s t r u c t i o n o f t h e g r i p s t r e n g t h d e t e c t o r e m b o d i me n t 200 i s be s t de sc r ibe d w i th r e fe re nc e to F IG . 12where the f ive layers a re sho-wn. For c la r i ty , the fourou te r l a ye r s a re d iv ide d in to uppe r a nd low e r ha lve sa nd p ro j e c t e d a bove a nd be low the c e n t ra l c y l inde r .H ow e ve r , t he c y l inde r s a re p re fe ra b ly c on t inuous a ndc onc e n t r i c . H o use d w i t h in de v ic e 200 i s t he e l e c t ron ic smodtile 252.The inne rmos t l a ye r (204 ) o f e mbod ime n t 200 i sprefe ra b ly c e l lu lo se bu ty ra t e t ub ing o f i nne r d i a me te r o f2 .54 c m (1 inc h ) a nd ou te r d i a me te r o f 3 .17 c m (11 /4inc h) . G o i ng ou tw a rd , t h e ne x t l a ye r (206 ) i s a c y l in de ro f s t e e l me sh s imi l a r t o w indow sc re e n . I t i s p re fe ra b lyso lde re d a t po in t 208 to a w i r e (210 ) a nd re in fo rc e d w i t he pox y c e me n t . The m e sh c y l inde r (206 ) p re fe ra b ly f it ssnug ly ov er th e ce l lu lose tubin g (204) , and is 144 cm^ ina r e a . T h e n e x t l a y e r ( 2 20 ) g o i n g o u t w a r d is P P T

F I G S . 8 and 9 re fe r to ti ii s devic e . FI G . 8 sh ow s an 35 polyuretiiane foa m p re fe ra b ly 0 .16 c m ( 1 /16 inc h ) t h i c k .A b ov e th i s i s a se c ond l a y e r o f s t e e l me s h (226 ) slightiyl a rge r i n d i a m e te r t ha n i t e m 206 . H o w e ve r , t he re a rep re fe ra b ly fou r g ro ove s (228 ,230 ,232 ,234) a bou t 1 mmw i de tha t e x t e nd f rom e d ge 260 to 4 mm f rom the o the re dg e o f t he c y l ind e r . Th us a t e nd 260 the me sh i s p re fe r a b ly d iv ide d in to fou r se pa ra t e se c t ions . H o w e ve r , a te nd 262 the se se c t ions a re e l e c t r i c a l ly c on t inuous . So l de r c onne c t ion 246 c onne c t s t h i s l a ye r o f me sh to w i re(248) . So lde r con nec t ion 24 6 is a lso re infor ced -with

o v e r a l l p e r s p e c t i v e v i e w . T h e a n k l e b r a c e e m b o d i m e n t(152) prefe rably f i t s be t -ween the ankle foot or thosis(A FO ) (150 ) a nd shoe (154 ) . (V e ry o f t e n the pa t i e n t-wi th cerebra l pa lsy has excess tone in the ca l f musc les.T h e A F O h e l p s t o c o n t r o l a n k l e m o v e m e n t i n t h e f ac e 4 0o f t h i s musc l e imba la nc e ) . W i re s (154 , 156 ) go to a ne l e c t ron ic s modu le . Th i s modu le i s i de n t i c a l i n a ppe a r a nc e to t he modu le 64 c onne c te d to t he c a s t boo t e mbod i me n t . The re fo re , i t i s no t spe c i f i c al ly i l l u s t r a t e dhe re . (A s a n a l t e rna t ive , t r a nsdu c e r 152 a nd mo du le 64 45 e pox y c e me n t . Th e ou te r mo s t l a ye r (250) i s p re fe ra b lyc ou ld b e f a b r ic a t e d a s i n t e g ra l pa r t s o f A F O 150 ).F IG . 9 be s t i l l u s t r a te s c ons t ruc t ion o f t h i s de v ic e . A sa bov e , t he re a re p re fe ra b ly f i ve l a ye r s . The y a re ( f romtop to bo t tom) th in rubbe r t op p i e c e (160 ) , s t e e l me shl a y e r ( 1 62 ) , P P T p o l y u r e t h a n e f o a m la y e r ( 16 4 ) ,se c ond s t e e l me sh l a ye r (166 ) a nd rubbe r bo t tom p ie c e(168 ) . W i re s 154 a nd 156 go to t he e l e c t ron ic s modu le .Ea c h l a ye r i s p re fe ra b ly o f i de n t i c a l t h i c kne ss a nd c om pos i t i on a s t he c a s t boo t e m bod ime n t .

ma de up o f gum rubbe r . W i re s 210 a nd 248 c o rme c t t oe l e c t ron ic s modu le 252 a s i nd i c a t e d by the da she s . A l ll a ye r s a re p re fe ra b ly g lue d toge the r -withC o n t a c t S p r a yA d h e s i v e ( 3 M c o m p a n y ) . ( H o w e v e r , o t h e r c o n t a c t50 a dhe s ive s ma y be u se d ) .To u se , t he pa t i e n t g ra sps t r a nsduc e r 200 a nd a pp l i e sfo rc e c e n t r ipe t a l l y ( i . e . , t o w a rd the c e n te r ) w i th thef inge r s a nd thumb . G roove s 228 (e t c . ) a l l ow the ou te rme sh e l e me n t 226 to c on t ra c t i n d i a me te r a s d i s t a nc eThe goa l o f t h i s de v ic e i s t o de fe a t t he t e nde nc y of 55 be tw e e n p l a t e s 226 a nd 206 de c re a se s p rop o r t ion a l t oc h i ld r e n w i th c e re b ra l pa l sy to t oe w a lk by c ons t a n t t he fo rc e a pp l i e d . Se c on da r i l y , c a pa c i t a nc e inc re a se s . Inre m inde r t o p l a n t t he he e l fi rs t a f t e r t he sw mg pha se o f t e s t i ng , c a pa c i t a nc e inc re a se s l i ne a r ly a nd re p rod uc ib lyga i t . U nfo r tuna t e ly , t oe w a lk ing f r e que n t ly pe r s i s t s f rom a s t a b l e ba se l ine . Th i s ba se l ine i s 78 pF . (no fo rc ee ve n i f A FO s a re w om . P r io r t o a n e xe rc i se se ss ion the a pph e d ) . C a pa c i t a nc e inc re a se s t o 148 pF . w i t h 70 lb s .de v ic e is c a hb r a t e d to e hc i t a sound a t o r ne a r t he pa - 60 a pph e d .t ie nt 's ful l w e ig h t . D u r in g the e xe rc i se se ss ion no r ma l G r ip s t r e n g th i s c a l ib ra t e d in pou nds p r io r c l i n i c alhe e l s t r i ke c a use s a t r a ns i e n t i nc re a se in c a pa c i t a nc e u se . T he pou nds se t t i ngs a re p re fe ra b ly p r in t e d a rou nda bo ve th re sh o ld c a us ing a n a ud ib l e r e w a rd s igna l t o be the a d ju s tm e n t knob . T he de s i r e d th re sh o ld fo rc e i s se te mi t t e d . H ow e ve r , i f t he foo t c om e s do -w n in e qu inus by the oc c up a t iona l t he ra p i s t a nd pa t i e n t use s t he de -(i .e. , toe s t r i ke i n s t e a d o f he e l s t r i ke ) t he c a p a c i t a nc e 65 v i c e a s i n s t ruc t e d . A s ound e mi t t e d a bo ve a t h re sho ldinc re a se doe s no t e xc e e d a p re se t t r i gg e r a nd no be e p i s se rve s a s a r e w a rd fo r ha v in g a c h ie ve d a g ive n c o m-e l ic i ted . This i s becatise a f t er t oe s t r i ke w e igh t i s ne v e r p re ss ion . (A l t e rn a t ive ly , it c ou ld be a n a l a rm to p re ve n tc onc e n t ra t e d in t he he e l . Th i s i nve n t ion wiU thus a ss is t e xc e e d in g a g ive n c om pre ss io n ) . Exp e r i e n c e w i l l de t e r -

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15 5,449,002 16mine i f subt le base l ine shi f ts occur wi th heavy use . I f so ,pe r iod ic r e -c a l ib ra t ion ma y be r e qu i re d .A l tho ug h a c y l ind r i c a l g ra sp i s i l l u s t r a t e d , t he r e a rese ve ra l o the r impor t a n t g ra sps . The se inc lude p inc h(i .e. , thum b a ga in s t t he l a te ra l i nde x f inge r) o r ba l l g ra sp 5(i .e. , han d grasp ing a ba i l ) . Th is invent ion , as a f lexib lel a mina te , ma y a c c ommoda te a ny o f t he se sha pe s a ndp rov ide f e e dba c k fo r ne a r ly a ny type o f g ra sp .E . A x i l l a r y C r u t c h D e v i c e JQ

T h i s e m b o d i m e n t i s s h o w n in F I G S . 1 3 - 1 5 . A n o v e r v i e w o f t he s i z e, sha pe a nd p l a c e m e n t o f t h i s e mbod i me n t i s i l l u s t r a t e d w i th r e fe re nc e to F IG S. 13 a nd 14 .A n a x i l l a ry c ru t c h (250 ) p re fe ra b ly ha s a rubb e r c a p(252) , which f i t s over a convex wood top-piece (254) . 15F r o m t h is , l o n g , v e r t i ca l , b o w e d w o o d m e m b e r s(256 ,258 ) c onv e rge o n the rubbe r ba se (260 ) . A t r a ns duc e r (262 ) i s p re fe ra b ly in t e rpose d be tw e e n ru bbe r c a p252 a nd the t op p i e c e 254 . T he o ve ra l l pe r im e te r o ft r a ns duc e r 262 i s p re fe ra b ly the sa m e a s t h i s top -p i e c e , 20and i t f i t s snugly inside the rubber cap . A se t of twow i re s f rom the t r a nsd uc e r (264 , 266 ) go to a n e l e c t ron icmodtile (268) fastened n ear the to p of one of thes e t w ov e r t i c a l w o o d m e m b e r s . I n t h e p r e f e r r e d e m b o d i m e n t ,mo du l e 268 ha s no e x t e rna l c o n t ro l s . In t e rna l ly , t he re is 25a n on -o f f sw i t c h , w e igh t t r i gge r c on t ro l a d ju s tme n t a ndp ie z oe l e c t r i c a l a rm de v ic e s imi l a r t o t he c a s t boo t e l e c t ron ic s modu le (64 ) .

T he c on s t ruc t ion o f t h i s t r a n sdu c e r i s be s t de sc r ib e dw i th r e fe re nc e to F IG . 15 . Th e re a re p re fe ra b ly s ix 30la ye r s f rom top to bo t tom. A n uppe rmos t l a ye r (280 ) i sp r e f e r a b l y m a d e o f O r t h o p l a s t , a i inc h th i c k se mi r ig id p l a s t i c t he sha pe o f w h ic h ma y be mo lde d a t t het e m pe ra tu re o f bo i hng w a te r . B e l ow th i s i s p re fe ra b ly acopper fo i l layer (282) , of the same length and width as 35the O r tho p la s t . W i re 264 i s so lde r e d f rom foU 282 tothe e l e c t ron ic s m odu le 268 . B e lo w th i s is a l a ye r o fpKDlyurethane foa m e l e m e n t s (284 ). P re fe ra b ly th e re a re24 suc h re c t a ngu la r p i e c e s , a bou t 0 .95 by 0 .50 c m.(0 .375 by 0 .2 inches) , regular ly spaced in a s taggered 40a r r a n g e m e n t . T h e s e p r e f e r a b ly c o v e r a b o u t 3 3 % of t h ea re a be tw e e n the a d j a c e n t l a ye r s . B e low th i s i s p re fe ra bly an oversized layer of th in rubber insula t ion (286) .Be lo w this is co pp er foU (288) essent ia l ly ident ic a l tofo il i t e m 282 . W i re 266 c onn e c t s t h i s l a ye r t o e l e c t ron ic s 45m o d u l e 2 6 8 . T h e b o t t o m l a y e r i s p r e f e r a b l y O r t h o plast

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17 5,449,002 18pling w e i g h t o v e r 18 e qu id i s t a n t mu c h sm a l l e r a re a ssensi t i -v i ty improved to 35 for the p r e f e r r e d e m b o d i m e n t .The o n l y c a v e a t for s a m p l i n gof d i sc re t e po in t sist h a t w e i g h tbe re l a t i ve ly e ve n ly a pp l i e d ove r th e ent i resu r fa c e .F or the g lu t e a l r e g ion th i s a ssum pt ionisr e a s o n - 5able.I n t e r m s of func t ion , e l e c t ron ic s mod u le64 is m o d i f ied in te rna l ly . Here , an inc re a se in w e igh t (vo l t a ge )a b o v e th e t r i g g e r set by k n o b 80 t u r n s off an a l a rm.C o n v e r s e l y , a d e c r e a s e in v o l t a g e ( w e i g h t ) b e l o w the 10t r i g g e r t u r n s on the a l a r m . T h i s is o p p o s i t e th e a l a r ms e q u e n c eof the cast boot de-vice .T o o p e r a t e , the n u r s e or phys i c a l t he ra p i s t has theg o a l of be ing no t i f i e d if a pa t i e n t is r is ing impulsive lyo u tof the -wheelcha ir .The t r i g g e ris thus p re fe ra b ly set 15t o a b o u t oneq u a r t e r th e pa t i e n t ' s -w eight w i t h kno b80.The de-viceise n g a g e dby t u r n i n gon s w i t c h90 .T h u s ,ifthe patient rises, th e a l a rm wDl s o u n d and h e l p s u m m o n e d . (In s o m e e m b o d i m e n t s , a d e l a ymay bebu i l t inso th e p a t i e n t may -w e igh t -sh if t w i tho u t s ound ing the 20a l a rm) .T h e o t h e rt wou s e s m e n t i o n e din thebe g inn ing o f t h i sse c t ion may be a c c o m p h s h e d by mod i f i c a t ion of e l e c t ron ic s on ly . For pa ra p le g i c s , a w e igh t - sh i f t off theg lu t e a l r e g ion w ou ld r e se t an t ime r c i r c u i t . If a s e c o n d 25w e igh t - sh i f t did not o c c u r w i t h a p re se t i n t e rva l , ana l a rm -would s o u n d .For the s t roke pa t i e n t , se t t i ng bo t ht o g g l e b r a k e s w o u l d d i s e n g a g e th e a l a rm c i r c u i t t ha t-w ou ld o the rw i se sound on s t a n d i n g or t r a ns fe r r ing .L a s t i y , th e upp e r p l a t e 322 is g r o u n d e d to p r e v e n t 30s t r a y c a pa c i t a nc e f rom a f fe c t ing w^eight m e a s u r e m e n t .

G . P r e s s u r e Pad E m b o d i m e n tF I G S . 19 and 20 re fe r to th i s de v ic e .F IG. 19 is ano v e r v i e w . The p r e s s u r e pad e m b o d i m e n t(400) is m o r e 35f lexib le than those d iscussed above by -virtueof c a r b o ni m p r e g n a t e d siUcone r u b b e r ( C I S R ) as the c o n d u c t i v el a ye r i n s t e a dof -wire mesh. Preferably , th e p r e s s u r epadi s c i rcula r . It is p r e fe r a b l y c o n n e c t e d by t h r e e w i r e s( i t e ms 402 ,404, and 406) to an e l e c t r o n i c s m o d u l e . T h i s 40

modtile is o the rw i se i de n t i c a l to e l e c t r o n i c s m o d u l e 62( c a s t b o o t e m b o d i m e n t ) . T h e r e f o r e ,it is not s h o w n .F I G . 20 be s t i l l u s t r a te s c on s t ruc t io n of the p re ssu rep a d e m b o d i m e n t 4 0 0 .A c lo th uppe r su r fa c e 410 p re fe r ably f i t s above a l a ye r of c a r b o n i m p r e g n a t e d s i li c o ne 45rubbe r (412 ) . The l a t t e r is p re fe ra b ly 0.16 cm. (1/16i nc h ) t h i c k . (H o-w e ve r ,0.08 cm. may a lsobe e m p l o y e dto increase f lexibUity) . Be low this pre fe rably is a l a ye ro fPPT po ly u re th a ne foa m (414 ) . B e l ow th i sis prefe r a b l y a c e n t ra l l a ye r of c a r b o n i m p r e g n a t e d s i h c o n e 50rubbe r (416 ) ,and b e l o w t h i sis a n o t h e r l a y e r of PPT (418) . Be low thisis the low e s t l a ye r of c a r b o n i m p r e g na t e d s ihc on e rub be r (420 ) . B e low l a y e r420 is the b o t t o m c l o t h l a y e r 424.L a y e r s are p re fe ra b ly g lue d -withN e opre ne c e me n t , a f t e r roughe n ing a ppos ing su r fa c e s 55wi th sandpaper , or o t h e r a p p r o p r i a t e a b r a s i v e . W i r e s4 0 2 , 404 and 406 are p re fe ra b ly g lue d to c o n d u c t i v el a ye r s 412, 416 and 420 re spe c t ive ly , by m e a n s of ac o n d u c t i v e s i l ic o n e r u b b e r c e m e n t . P P T l a y e r s 414a n d418 and c lo th l a ye r s 410 and 424 are p re fe ra b ly of 60e q u i v a l e n t d i a m e t e rand 0.5 cm g r e a t e rin d i a me te r t ha ns i l i c one rubbe r l a ye r s 412, 416 and 420.

A p p l i c a t i o n of -weight inc re a se s c a pa c i t a nc e by c o m p re ss ing foa m l a ye r s 414 and 418. Th i s b r ings c lo se rc o n d u c t i v e l a y e r s 412, 416 and 420. T e s t i n g r e v e a l s a 65l i ne a r r e l a t i onsh ip be tw e e n w e igh t and c a pa c i t a nc e .T h i s is t r u e for va r ious a re a s of w e i g h t a p p h c a t i o n ,simi la rto t h a t s h o w nin FIG. 4.

I n p r e v io u s l y d e s c r i b e d e m b o d i m e n t s t h e r e was on lyone c a pa c i t i ve l a ye r , ma deup of tw o c o n d u c t i v e l a y e r sw i th i n t e rpose d d i e l e c t r i c foa m. In those , on ly one su r face, th e l a ye r c lo se s t to the pa t i e n t , was e lec t r ica l lysh i e lde d . O n ly th i s s ide c ou ld f a c e th e pa t i e n t w i t hou tp r o d u c i n g s p u r i o u s r e a d i n g s . T h o s e e m b o d i m e n t s aresa id to be p o l a r i z e d . For t h i s e m b o d i m e n t t h e r e areessent ia l ly t-woc a pa c i t i v e l a ye r sin pa ra l l e l . B o th ou te rsu r fa c e s are g ro und e d ( i .e . , sh i e lde d ) . Th us , e i t he r su r facemayfacet hepa t i e n t w i tho u t c a us ing spu r ious r e a d i n g s . T h i s e m b o d i m e n t is t h u s n o n - p o l a r i z e d .C I S R is a suspe ns ion of sma l l c a rb on pa r t i c l e s w i th ins i l i c one rubbe r . Its c o n d u c t i v i t y is directiy re l a t e d tof r e que nc y ; it is c o n d u c t i v e to AC but not DC signa ls .S i n c e e l e c t r o n i c s m o d u l e 408 me a s u re s c a pa c i t a n c eus ingA C s igna l s , rubbe r l a ye r s be ha ve as-would me ta lc o n d u c t o r sin th i s c on te x t . Th i s se nso rist h e r e f o r e prefe ra b ly ma de -w i thou t me ta l , e xc lud ing th e w i r e s (402404or 406).W i t h r e s p e c t to a pp l i c a t ion , t h i s e mbod ime n t is forge ne ra l i som e t r i c s t r e ng the n ing ( i . e ., o the r t ha n g r ips t r e n g t h e n i n g ) .T het h e r a p i s tmaypos i t i onthede-viceinf ron t of the a nk leandb e h i n d an i m m o v a b l e s u r f a ce forq u a d r i c e p s s t r e n g t h e n i n g , b e h i n d th ea n k l eand in front

o f an i m m o v a b l e s u r f a ce for h a m s t r i n g s t r e n g t h e n i n g ,o r b e t w e e n th e k n e e and waU for g lu t e us me d iuss t r e n g t h e n i n g . T h e r emay be o c c a s i o n s w h e r eth e bo thsu r fa c e s are in c o n t a c t w i t h the pa t i e n t , as if p l a c e db e t w e e n th e k n e e s for a d d u c t o r s t r e n g t h e n i n g . In thisc a se doub le sh i e ld ing p re ve n t s spu r ious r e a d ings . Thepa t i e n t ga in s r e w a rd for re a c h ing c e r t a in s t r e ng th goa l sby a ud i to ry f e e dba c k .I n o t h e r e m b o d i m e n t s , th e de v ic e c ou ld be m a d e ar e c t a n g u l a r s h a p eofva r io us d ime ns ion s . N on-p o la r i z e dp a d s c o u l dbe use dfor s t r e n g t h and e ndu ra nc e t r a in ing .N o n - p o l a r i z e d r e c t a n g u l a r p a d s c o u l d be m a d e to fitva r ious c a s t boo t s i z e s , and t a k e th e p l a c e of the castb o o t e m b o d i m e n t . N o n - p o l a r i z e d i n n e r - s o l e s h a p e dde v ic e s c ou ld t a ke th e p l a c e of the s h o e e m b o d i m e n t .N on -po la r i z e d c i r c u l a r de -vi ce s c ou ld t a ke th e p l a c e of

t h e A F O e m b o d i m e n t. Fiuther, very thin ( i .e . ,0.8 cm.or l e ss ) c onduc t ive s ihc one rubbe r l a ye r s wo-uld m a k efor ver y f lexible, res i l ient de-vices be tw een i r re gula rsurfaces.A d d i t i o n a l i m p r o v e m e n t s c o u l d bem a d eto the e l e c t ron ic modu le . C on t inuous d ig i t a l d i sp l a y of w e i g h t inp o u n d s is p o s s ib l e . T h i s w o u l d be ve ry he lp fu l forw e igh t t r a in ing . B e yond th i s ,a po r t a b l e d ig i t a l sc a lefort he ma ss ma rke t c ou ld be m a d e in the foUo-wing way:T w o r e c t a n g u l a r or inne r - so l e sha pe d p re ssu re pa dsc o u l d be pos i t i one d on a f lexib le p las t ic sc ree n. T he sepads -wouldbec o n n e c t e d to a smaU e l e c t ron ic s m odu lew i th d ig i t a l r e a dou t in pounds , a l so pos i t i one d on thes c r e e n . For a w e i g h t c o n s c i o u s p e r s o n a l w a y s on them o v e ,thed e v i c e c o u l dbeu n r o l l e d o n t oa ha rd su r fa c es u c h as a ho te l ba th roo m f loor and re-roUedfor t r a ve l .A c c o r d i n g l y , ther e a d e r -wUlseetha t t h i s i nve n t ionisa c a p a c i t i v e t r a n s d u c e r -with w ide po te n t i a l a pp l i c a t ionin th ea r e a of re ha b i l i t a t i on me d ic ine and a lsoth e ma ssm a r k e t for e xe rc i se or t o n i n g d e v i c e s . In o p e r a t i o n thed e v i c e m e a s u r e s th e c a pa c i t a nc e c ha nge be t -w e e n twome ta l sc re e ns p re fe ra b ly se pa ra t e d by a ope n c e l l po ly u r e t h a n e f o a m d i e l e c t r i c k n o w n as P P T . In s o m ee m b o d i m e n t s , the m e t a l s c r e e n is r e p l a c e d by e last icc o n d u c t i v e s i h c o n e r u b b e r . As w e i g h t is a pp l i e d , thef o a m c o m p r e s s e s and c a pa c i t a nc e inc re a se s .A l t h o u g h th e c o n c e p t of the c a pa c i t i ve t r a nsdu c t ionis not ne-w, th i s de -v i ce posse sse s ma n y impo r t a n t im-

Prov idedbyPa ten tS to rm h t t p : / / w w w . p a t e n t s t o r m . u s

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19 5,449,002 2 0prove d p rope r t i e s . The se inc lud ing unsu rpa sse d re s i l i e nc y a n d du ra b i l i t y o f t he d i e l e c t r i c . R e sp onse i s l i ne a ra nd re p roduc ib l e . I t a dd i t i ona l ly ha s t he a b i l i t y t o me a s u r e -weight a c c u ra t e ly w he n a pp l i e d ove r a l a rge o rsma l l a re a v i a i r r e gu la r su r fa c e s . C on s t ruc t ion i s s imp le , 5a nd re a d i ly a va i l a b l e e l e c t ron ic s ma y be u se d w i th ve rylow c u r re n t d ra in . Sma l l ba t t e r i e s ma y thus pow e r the sede v ic e s ove r a l ong pe r iod o f t ime .T h e m a t e r i a l s t h a t c r e a t e th e s e i m p r o v e m e n t s h a v eb e e n w^ell kno w n in the f ie ld fo r some t ime . H ow e ve r , 10no one ha s t hough t t o a pp ly the m to so lve the impor t a n tp r o b l e m o f h o w t o m e a s u r e l i m b l o a d i n g . T h e r e f o r et h e s e i m p r o v e m e n t s a r e n o t o b v i o u s .A dd i t i ona l ly , t he p r io r a r t ha s so f a r be e n to t a l l yunsuc c e ss fu l i n me e t ing the ne e d fo r l oa d mon i to r ing . 15Very l i t t le of the pr ior a r t i s ac tua l ly in use . This i s t ruee ve n though the po te n t i a l ma rke t i s huge .Th i s i nve n t ion i s b ro a d in a pp l i c a t ion . I t ha s m a nyspe c i f i c e mbod ime n t s i n t he a re a s o f shoe s , p ro s the t i c s ,o r th o t i c s , a ss is t de v ic e s a nd w he e lc ha i r s . T he inve n t ion 20w ou ld be o f i n t e re s t t o t he phys i a t r i s t , o r thope d ic o rp l a s t i c su rge on , phys i c a l a nd oc c upa t iona l t he ra p i s t . I t sw ide r a nge o f po t e n t i a l u se s t e ms f rom th in s i z e , a ndabi l i ty to assume di ffe rent shapes.T he d