1969, No. I 23

IA muscle stimulator for hemiplegie patients

Certain nervous disorders or damage to the braincan have the result that the muscles used in lifting thefoot during walking are not activated, or are onlypartly activated. A patient with this disability (some-times called drop-foot) is in danger of stumbling overhis own foot, and when walking therefore tends to re-main standing on the sound leg until the affected oneis safely and securelyon the ground. This gives him adragging gait, and even with a walking-stick he movesonly with difficulty.

It has been found that this disability can often belargely overcome if an electrical stimulus is applied atthe appropriate instant to the nerve that causes themuscles involved to contract. A portable electronicmuscle stimulator for this purpose has been developedand tested by the lnstitute for Perception Research incooperation with the Stichting Revalidatie (Centre forthe Rehabilitation of the Physically Disabled), Eindho-ven.

The main problem was to synchronize the periodical-ly supplied stimuli with the patient's walk. In earlierinvestigations in this field experiments were carried outwith a rnechanical switch placed under the heel of theaffected foot [IJ. The disadvantage of this arrangementwas that the stimuli were switched on and off at timeswhich came too soon with respect to the desired cycleof lifting and lowering the foot. A better place for theswitch was under the bali of the affected foot, but ow-ing to the vulnerability and rapid wear of mechanicalswitches placed outside the shoe (and since these onlywork properlyon hard, level ground) the solution wasnot satisfactory.

We have now obtained very good results with apneumatic switch which is operated by a small airchamber in a rubber insole fitted in the shoe on theunaffected foot. The air chamber is situated under theball of the foot; the instants at which the ball of thisfoot touches and leaves the ground or, to be moreexact, the instants at which the weight of the body isplaced on the insole and removed again coincide veryclosely with the start and the end of the swing of theaffected foot. The instants at which the muscles of thisfoot contract and relax are thus controlled correctlyfrom the movement of the patient as he walks.

Fig. I shows the appliance in use, andfig. 2 the insolewith the switch. The generator, i.e. the stimulator

[1] W. T. Liberson, H. J. Holmquest, D. Scot and M. Dow,Functional electrotherapy: stimulation of the peroneal nervesynchronized with the swing phase of the gait of hemiplegiepatients, Arch. phys. Med. Rehabil. 42,101-105,1961.

Fig. I. The muscle stimulator in use. A rubber insole containinga small air chamber, con nected by a flexible tube to a pneumaticswitch, is fitted in the shoe on the unaffected foot. When thepatient walks, the pneumatic switch (attached to the lower legby means of an elastic bandage) is operated and switches thestimulator on and off. The stimulator, which is carried on a beltaround the waist, applies pulses to an electrode in the elasticbandage around the affected leg.

proper, is carried on a belt around the patient's waist,and delivers a rectangular pulse at arepetition rate of50 Hz, 0.6 ms duration and a maximum amplitude of100 V (rated current 6 mA). The amplitude of the pulsecan be varied by means of a potentiometer. An elasticbandage immediately under the knee of the affectedleg carries the two electrodes which are energized bythe pulses. The positive (passive) electrode is made ofelectrically conducting rubber and is in direct contactwith the skin. The other (active) electrode, to which amaximum of LOOV is applied, is made of stainless steeland makes contact with the skin through a damp spongeto avoid a high contact resistance.

The system has proved to be very reliable and the

24 PHILlPS TECHNICAL REVIEW VOLUME 30

switch operates on any kind of floor covering or pavedsurface without getting damaged. This is a very impor-tant point, since it gives the patient confidence in theappliance.

For some considerable time now the appliance hasbeen under test at the Eindhoven Centre for the Rehab-ilitation of the Physically Disabled. As a result of usingthe appliance many patients have developed a practi-

The appliance is also being used on children with adrop-foot disability due to a brain defect contractedbefore or during birth. These children were not ableto learn to walk normally. Some of these children whoare paralysed on one side only (herniplegia) have beenunder treatment for several months and have now be-gun to develop a more normal gait. For children para-lysed on both sides (diplegia) an appliance with two

Fig.2. Insole with flexible tube and pneumatic switch.

cally normal gait. An important contributory factorwas found to be that the affected leg is better directedwhen the foot is placed on the ground and thereforestands more securely in the "standing" phase. It isinteresting to note that after some time many patientsretain the improvement in their walk even withoutfurther use of the appliance. Out of 60 patients over40 years of age who underwent the treatment for threeto six weeks, 50 recovered completely or show con-siderable improvement. The other patients respondedwell while walking with the appliance, but showed nolasting improvement. Two of these patients with noautonomous muscle control have been using the appli-ance constantly for more than six months, and arewalking confidently.

separately adjustable outputs is now being tested; theinsole here is placed under the less-affected foot. Thisinvestigation is still in progress.

The results so far obtained with this appliance havedemonstrated its helpful effect in the cases we havementioned. It appears likely that the muscle stimulatorwill also be a useful aid for spastic children, and pos-sibly for certain polio patients.

H. J. van LeeuwenJ. Vredenbregt

H. J. van Leeuwen is with the Stichting Revalidatie, Eindhoven;J. Vredenbregt is with the Institute for Perception Research, Eind-hoven.

1969, No. 1 25

Recent scientific publicationsThese publications are contributed by staff of laboratories and plants which formpart of or co-operate with enterprises of the Philips group of companies, particularlyby staff of the following research laboratories:

Philips Research Laboratories, Eindhoven, Netherlands EMullard Research Laboratories, RedhilI (Surrey), England MLaboratoires d'Electronique et de Physique AppIiquée, Limeil-Brévannes

(Val-de-Marne), France LPhilips Zentrallaboratorium GmbH, Aachen laboratory, Weisshausstrasse,

51 Aachen, Germany APhilips Zentrallaboratorium GmbH, Hamburg laboratory, Vogt-Kölln-

Strasse 30, 2 Hamburg-Stellingen, Germany HMBLE Laboratoire de Recherches, 2 avenue Van Becelaere, Brussels 17

(Boitsfort), Belgium. ' B

Reprints of most of these publications will be available in the near future. Requestsfor reprints should be addressed to the respective laboratories (see the code letter) orto Philips Research Laboratories, Eindhoven, Netherlands.

D. Andrew: A cycloidal path mass spectrometer appliedto the measurement of the speed of sputter ion pumps.Mass Spectrometry, Proc. Symp. Enfield College ofTechnology 1967, p. 129-137; 1968. M

G. Arlt & H. Schweppe: Paratellurite, a new piezo-electric material.Solid State Comm. 6, 783-784, 1968 (No. 11). A

L. K. H. van Beek, J. Boven & J. Helfferich: Propertiesof diazosulfonates, Part V. The effect of substituentson spectra and dissociation of 4-dimethylaminoben-zenediazosulfonate.Rec. Trav. chim. Pays-Bas 87, 737-745, 1968 (No. 8). E

V. Belevitch & Ph. Piret: Théorie de I'oscillateur à deuxfréquences d'accord dont Ie rapport est voisin de 3.Rev. HF 7, 171-176, 1968 (No. 6). B

G. Blasse: Influence of crystal structure on lumines-cence.Mat. Res. Bull. 3, 807-815, 1968 (No. 10). E

G. Blasse & A. Bril: Photoluminescent efficiency ofphosphors with electronic transitions in localized cen-ters.J. Electrochem. Soc. 115, 1067-1075, 1968 (No. 10). E

- G. Blasse, A. Bril & W. C. Nieuwpoort: On the Euê+fluorescence in several mixed metal oxides.Proc. int. Conf. on Luminescence, Budapest 1966,'Vol. 2, p. 1646-1650; 1968. E

G. Blasse, A. Bril & J. de Vries: Fluorescence of Eu2+-activated barium octaborate.J. Electrochem. Soc. 115, 977-978, 1968 (No. 9). E

R. Bleekrode: Contribution to the study of "abnormal"rotational energy distributions in the Call,,-Ballg bandsof 14N2.

J. chem. Phys. 49, 951-953, 1968 (No. 2). E

R. Bleekrode: A spectroscopie method for the deter-mination of temperatures in hot gaseous systems.Physics Letters 27A, 673-674, 1968 (No. 10). E

A. J. van Bommel & F. Meyer: Reply to the commentof H. K. Lintz concerning "LEED study of a nickelinduced surface structure on silicon (111)".Surface Sci. 12. 391-392, 1968 (No. 2). E

H. Bosma: A general model-for junction circulators;choice of magnetization and bias field.IEEE Trans. MAG-4, 587-596, 1968 (No. 3). E

G.-A. Boutry, H. Dormont, J.-C. Richard & P. Saget:Etude de films épitaxiés de potassium et de rubidiumpar diffraction d'électrons de faible énergie.C.R. Acad. Sci. Paris 267B, 255-258, 1968 (No. 4). L

G. Bouwhuis: On the anomalous circular polarizationof the 1.523 (.L He-Ne laser line.Physics Letters 27A, 693, 1968 (No. 10). E

A. Bril: Report on application of luminescence.Proc. int. Conf. on Luminescence, Budapest 1966, Vol.2, p. 2112-2117; 1968. E

A. Bril, W. C. Nieuwpoort, W. L. Wanmaker (PhilipsLighting Division, Eindhoven), G. Blasse & C. D. J. C.de Laat: On the transfer of energy in europium-acti-vated phosphors.Proc. int. Conf. on Luminescence, Budapest 1966, Vol.2, p. 1689-1693; 1968. E

C. F. Brockelsby: Mullard Research Laboratories,RedhiIl, Surrey.N.E.C. Rev. (National Electronics Council) 4, 117-124,1968 (No. 4). M

J. J. van den Broek: Determination ofternary diffusioncoefficients.Scripta metall. 2, 561-564, 1968 (No. 10). E

26 PHILIPS TECHNICAL REVIEW VOLUME 30

C. M. van der Burgt: Enkele toepassingenvan ultrage-luid, IV. Piëzomagnetische en piëzo-elektrische trans-ducenten voor diverse ultrasone toepassingen.Ingenieur 80, 0168-181., 1968 (No. 45). E

K. H. J. Buschow, J. F. Fast & A. S. van der Goot:Magnetic properties of some Co-rich erbium cobaltintermetallic compounds.Phys. Stat. sol. 29, 825-829, 1968 (No. 2). E

H. B. G. Casimir: Chimistes, physiciens et ingénieurs,Jeur collaboration .dans la recherche industrielle.Proc. 36èmeCongrès int. de chimie industrielle, Bruxel-les 1966, p. 64-66; 1968. E

H. B. G. Casimir: On electromagnetic units.Helv. phys. Acta 41, 741-742, 1968 (No. 6/7).

E. Constant (Faculté des Sciences de LiIle) & A. Semi-chon: Diodes semiconductrices en régime d'avalanche.Application aux hyperfréquences.Onde électr. 48, .703-721, 1968 (No. 496/497). L

C. D. Corbey, R. Davies & B. H. Newton: Varactorharmonic-generator chain as a pump source for aparametrie amplifier.Electronics Letters 4, 397-398, 1968 (No. 19). M

C. Crevecoeur&H. J. deWit: Dipole relaxation inMnO,doped with Li.Solid State Comm. 6, 843-845, 1968 (No. 12). E

H. J. van Daal: The static dielectric constant of Sn02.J. appl. Phys. 39, 4467-4469, f968 (No. 9). E

J. Dieleman: On the utilization of electron spin reso-nance results: illustration with the aid of the (3d) tran-sition elements in some U-VI compounds.Proc. int. Conf. on Luminescence, Budapest 1966, Vol.2, p. 2131-2141; 1968. E

A. M. van Diepen (Natuurkundig Laboratorium derUniversiteit van Amsterdam), H. W. de Wijn (N.L.Univ. Amst). & K. H, J. Buschow: Nuclear magneticresonance and susceptibility of equiatomic rare-earth-aluminum compounds.Phys: Stat. sol. 29, 189-192, 1968 (No. I). E

C. Z. van Doorn: Recombination mechanisms for the"edge" emission in cadmium sulphide.Proc. int. Conf. on Luminescence, Budapest 1966, Vol.1, p. 1124-1130; 1968. E

C. Z. van Doorn & J. H. Haanstra: Simple improve-ment of Hinteregger-Iamp continua by a titanium get-ter.AppL Optics 7, 1655-1656, 1968 (No. 8). E

J. Durieu & Y. Genin: Determination of an orbit fromonly three angular measurements.AIAA J. 6, 1432-1433, 1968 (No. 7). B

G. Engelsma: Zeitmessung in Pflanzen.Umschau in Wiss. u. Technik 68, 727-728, 1968 (No.~. E

U. Enz: Der photomagnetische Effekt.Relv. phys. Acta 41, 781-784, 1968 (No. 6/7).

J. Flinn: Extent of the I/J noise spectrum.Nature 219, 1356-1357, 1968 (No. 5161).

E

M

N. V. Franssen: Über die Frequenzkurven elektro-akustisch gekoppelter Räume und ihre Bedeutung fürdie künstliche Nachhallverlängerung.Acustica 20, 108-109, 1968 (No. 2). E

N. J. Freedman & L. K. Brundle: Nonlinear behaviourof magnetostatic surface waves.Electronics Letters 4, 427-428, 1968(No. 20). M

EY. Geoin: Gaussian estimates and modern linear dis- .crete filtering methods.Rev. A10, 70-75, 1968 (No. 2). B

A. H. Gomes de Mesquita: The direct structure deter-mination of a silicon carbide crystal of type 120R.Acta cryst. B 24, 1461-1466, 1968 (No. 11). E

E. E. Havinga: W-like dependence of critical tempera-ture on number of valence electrons in non-transitionmetal Cu-Au-type alloys.Physics Letters 28A, 350-351, 1968 (No. 5). E

J. C. M. Henning & H. van den Boom: ESR studies ondivalent iron in CS3ZnCI5.Physics Letters 27A, 685-686, 1968 (No. 10). E

W. Hermann: Internal friction in IlI-V- compounds be-low room temperature.Solid State Comm. 6, 641-644, 1968 (No. 9). A

A. H. Hoekstra (Philips Lighting Division, Eindhoven):The reaction of calcium chlorine apatite with antimonytrioxide.Proc. int. Conf. on Luminescence, Budapest 1966,Vol.2, p. 1337-1341; 1968.

Th. Holtwijk & W. Lems: The iron curtain, a batch-fabricated storage array.IEEE Trans. MAG-4, 561-564, 1968 (No. 3). E

H. Jonker, Th. P. G. W. Thijssens & L. K. H. vanBeek:Properties of diazosulfonates, Part VI. Quantum yieldsfor the photolysis of 2-methoxybenzenediazonium andfor the photo-isomerization of 2-methoxybenzene-trans-diazosulfonate. .Rec. Trav. chim. Pays-Bas 87, 997-1005,1968 (No. 10).

E

H. Kalis & J. Lemmrich: Frequenzanaloge Drehzahl-.regelungen, I, 11.Regelungstechnik 16,497-502, 555-562, 1968 (Nos. U,12). H

D. J. Kroon: Opening, tweede hoogbouwPhilips Na-tuurkundig Laboratorium ..Ned. T. Natuurk. 34, 344-346, 1968 (No. 11). E

K. Lagemann: Ein Vorschlag zur Darstellung asyn-chron betriebener, JK-F.lipflops.Elektron. Rechenanl. 10, 171-176, 1968 (No. 4). If

1969, No. I RECENT SCIENTIFIC PUBLICATIONS 27

H. Leich (Faculté Polytechnique de Mons) & Ph. vanBastelaer: La synthèse des quadripöles non dissipatifsau moyen de capacités et de gyrateurs déséquilibrés.Rev. MBLE 11, 31-48, 1968 (No. 2). B

F. A. Lootsma: Constrained optimization via penaltyfunctions.Philips Res. Repts. 23,408-423, 1968 (No. 5). E

F. A. Lootsma: Constrained optimization via para-meter-free penalty functions. •Philips Res. Repts. 23, 424-437, 1968 (No. 5). E

F. K. Lotgering: Spin canting in MnCr2S4.J. Phys. Chem, Solids 29,2193-2197,1968 (No. 12). E

R. J. Meijer: Der Philips-Stirlingmotor.Motortechn. Z. 29, 284-298, 1968 (No. 7). E

C. H. de Minjer: Bepaling van de gevoeligheid vanputvormige corrosie van roestvrij staal.Polytechn. T. Procestechniek 23, 587-595, 1968(No. 17). E

P. Nagels (Solid State Physics Dept. SCK, Mol, Bel-gium), M. Denayer (S. S. Phys. Dept. SCK, Mol), H. J.de Wit & c. Crevecoeur: Comments on "The Hallmobility of electrons and holes' in MnO at high tem-perature" by Gvishi et al.Solid State Comm. 6, 695-696, 1968 (No. 10). E

A. G. van Nie: Noise level and zero-drift of broad-bandelectrometers used for measuring small currents.Electronic Engng. 40, 520-523, 1968 (No. 487). E

M. Noé: Problèmes d'interconnexion optimale (Ircpartie).Rev. MBLE 11, 1-12, 1968 (N~. 1). B

G. Piétri: The transfer method, a new technique for thesensitization of photoelectric tubes.IEEE Trans. NS-15, No. 3, 171-178, 1968. L

L. J. van de Polder: Courbe de réponse spectrale désiréedu tube "Plumbicon" et du système optique dans unecaméra de télévision en couleur.Onde électr. 48, 880-883, 1968 (No. 499). E

K. Reiber: Absorption von Ultraschall in Tellur.Solid State Comm. 6, 779-781, 1968 (No. 11). A

J. Roos & J. Koorneef: Thin bilaminar piezodisks usedas microphone and telephone membranes.35th Conv. Audio Engng. Soc., New York 1968, pre-print No. 589 (J-5), 3 pp.' E

W. Schilz; Anisotropy of high-field helicon propaga-tion in PbTe. .Phys. Stat. sol..29, 559-568, 1968 (No. 2): H

J. G. Siekman: Cutting of thin metal films with a CO2-gas laser beam. . .. .Microelectronics and Reliability' 7, 305-311, 1968(No.4). " . '. . E

M. J. Sparnaay: On the attraction between two platesof semiconducting materials which are electricallyconnected.Proc. Kon. Ned. Akad. Wetensch. B 71,387·395, 1968(No.5). E

J. M. Stevels: Struktur und elektrische Eigenschaftenvon Gläsern.Haus der Technik - Vortragsveröffentlichungen No.188,6-16, 1968. E

H. J.L.Trap: Anwendungsbereiche neuerer glasartigerStoffe in der Elektronik.Haus der Technik - Vortragsveröffentlichungen No.188,64-76, 1968. E

H. J. L. Trap: Elektronenleitung in Glas.Elektro-Anzeiger, Ausg. ges. Industrie, 21, 317-322,1968 (No. 15). E

M. T. Vlaardingerbroek, G. A. Acket, K. Hofmann &P. M. Boers: Reduced build-up of domains in sheet-type gallium-arsenide Gunn oscillators.Physics Letters 28A, 97, 1968 (No. 2). E

M. T. Vlaardingerbroek, W. Kuypers & G. A. Acket:Energy relaxation time of hot electrons in GaAs.Physics Letters 28A, 155-156, 1968 (No. 2). . E

G. Vonk: A new type of compact heat exchanger witha high thermal efficiency.Adv. cryog. Engng. 13, 582-..589,1968. E

J. Vredenbregt & W. G. Koster (Institute for Percep-tion Research, Eindhoven): Measurements on electricaland mechanical activity of the elbow flexors.Biomechanics I, 1st Int. Seminar, Zürich 1967, p.102-105; 1968.

K. Walther: Anisotropy of magnetoacoustic attenua-tion and deformation potential in bismuth.Phys. Rev. 174, 782~790, 19?8 (No. 3). H

W. L. Wanrnaker, J. G. C. M: de Bres & J. W. terVrugt (Philips Lighting Division, Eindhoven): Fluores-cence of some Ga and In containing alkaline earthorthophosphates.Proc. int. Conf. on Luminescence, Budapest 1966, Vol.2, p. 1370-1373; 1968.

W. L. Wanmaker (Philips Lighting Division, Eindho-ven), A. Bril, J. W. ter Vrugt (Philips L'.D.) & J. Broos. (Philips Electronic Components and Materials Divi-sion, Eindhoven): Luminescent properties of europium-activated phosphors of the type AIIIBv04•

Proc. int. Conf. on Luminescence, Budapest 1966, Vol.2, p. 1633-1638; 1968. 'E

C. H. Weijsenfeld: A core model explaining Hall effectand resistivity in -the mixed state of type 11'supercon-ductors.Physics Letters 28A, 362-363, 1968 (No. 5). E

28 PHILlPS TECHNICAL REVIEW VOLUME 30

K. Weiss: Thermische Ausdehnung von reinem unddotiettem NaCI.Z. phys. Chemie Neue Folge 61, 257-261, 1968 (No.5/6). ~H. W. Werner & H. A. M. de Grefte: Improvements innoise level and zero drift of a broadband electrometerused for ion detection in a mass spectrometer.Electronic Engng. 40, 493-496, 1968 (No. 487). sH. W. de Wijn (Natuurkundig Laboratorium der Uni-versiteit van Amsterdam), K. H. J. Buschow & A. M.van Diepen (N.L. Univ. Amst.): Experimental evidencefor interband mixing in rare-earth intermetallic com-pounds.Phys. Stat. sol. 30, 759-766, 1968 (No. 2). ~

H. C. Wright, R. J. Downey & J. R. Canning: Conduc-tivity storage in CdS.Brit. J. appl. Phys. (J. Physics D), ser. 2, 1, 1593-1601,1968 (No. 12). M

G. Zanmarchi: Free and trapped electron recombinationluminescence of the aluminium centre in cubic SIC.Proc. int. Conf. on Luminescence, Budapest 1966, Vol.2, p. 1482-1489; 1968. t:

G. Zanmarchi: Luminescence of the aluminium centrein cubic SiC: dependence ofthe recombination rates onthe intensity of the light excitation.J. Phys. Chem. Solids 29, 1727-1736, 1968 (No. I0). eG. Zanmarchi & C. Haas: Magnon drag.Philips Res. Repts. 23, 389-407, 1968 (No. 5). t:

A. L. Zijlstra & A. .J. Burggraaf (Philips Glass Division,Eindhoven): Fracture phenomena and strength proper-ties of chemically and physically strengthened glass,J. General survey of strength and fracture behaviourof strengthened glass.J. non-cryst. Solids 1, 49-68, 1968 (No. I).

Contents of Philips Telecornmunication Review 28, No. 1, 1968:

H. J. Kramer: The SR 600 series of transistorized radio-link equipment (p. 1-20).A. E. Serrure: Test results on 6 MHz telephone line equipment on small-bore coaxial cables on a trial routebetween Brussels and Dendermonde (p. 21-30).P. W. L. van Iterson: 5 kW HF communication lSB transmitter with transistorized driving equipment seriesRZ 510 (p. 31-43).

Contents of Mullard Technical Communications 10, No. 95, 1968:

S. Sijtstra: Vertical deflection amplifier for 150 MHz oscilloscope (p. 158-166).K. Hart & F. G. Oude Moleman: Horizontal deflection amplifier for 150 MHz oscilloscope (p. 167-174).P. A. Neeteson: Schmitt trigger as level detector: analysis and performance of FCL 101 (p. 175-181).F. A. Sowan: Light units in SI (p. 182-184).

Contents of Mullard Technical Communications 10, No. 96, 1968:

J. Catherall: Automatic magnetiser and flux-setter for d.c. permanent magnet motors (p. 186-189).A. Ciuciura: Proteetion against flash over in television picture tubes (p. 190-192).G. W. Broekema: C.r.t.- grid drive circuit using d.c. restoration of the unblanking signal (p. 193-202).M. C. Gander: Transistor video amplifier design for monochrome tv receivers (p. 203-208).

Contents of Valvo Berichte 14, No. 4, 1968:

P. Gerdsen & F. Weitzsch: Grundlagen für die WeiBpunktänderung bei Farbfernsehempfängern (p. 121-135).H. Achterberg & J.Wölber: Die für eine gute Schirmbildqualität erforderlichen Eigenschaften des PAL-Decoderseinschlieûlich der Verzögerungsleitung, J (p, 137-168).

------- ----------------------------------Volume 30,1969, No.1 pages 1-28 Published 15th Apri I 1969