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An Introduction to Functional Electrical Stimulation Presented by: Fereshteh Lagzi.

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Presentation on theme: "An Introduction to Functional Electrical Stimulation Presented by: Fereshteh Lagzi."— Presentation transcript:

1 An Introduction to Functional Electrical Stimulation Presented by: Fereshteh Lagzi

2 Presentation Agenda Introduction History of FES FES systems main components Electrodes Muscles, Neural and electrical stimulation Examples of Commercial systems

3 ES applications

4 FES system’s main components فيدبك سيستم اراده و هوشياري كاربر فرامين ارادي پردازش‌گر و كنترل‌گر فرامين منبع تغذيه پارامترهاي تحريك تحريك كننده الكترودها انقباض عضلاني موقعيت مفصل اتصالات الكترودها تحريك حركت واسط كاربر- سيستم حسگر نيرو حسگر موقعيت

5 Muscles neural ans electrical Stimulation Pulse amplitude Pulse width MuscleNerve Skeletal Muscle fibers: Type I : red, slow, aerobic Type II : white, fast, anaerobic Alpha motor neurons: small alpha motor neurons : innervate slow muscle fibers large alpha motor neurons : innervate fast muscle fibers

6 Muscles neural ans electrical Stimulation Muscle contraction mechanisms: recruitment : activation of an increasing number of motor units within a muscle on contraction temporal summation : increasing firing rate of active motor units During voluntary activation, recruitment and temporal summation are two mechanisms that regulate the strenght of muscle contraction, and usually these mechanisms act simultaneously

7 Types of Electrodes  Polarizable electrodes: Ag  Nonpolarizable electrodes: Ag_ AgCl

8 Electrode- Tissue Behavior


10 Electrode Operating Characteristics




14 Current wave forms

15 Electrode Material In choosing the material for an electrode the following factors are of importance: (1) Passive compatibility of the material with tissue (2) Extent of reversible behavior (3) Mechanical compatibility with the tissue

16 Electrode Placement (1) Skin Surface Electrode (2) Epimysial Electrode (3) Nerve Cuff Electrode (4) Percutaneous Intramuscular Electrode (5) Intramuscular Electrode (1) (2) (3) (4) (5)

17 Electrodes Nerve Cuff Electrode Wrapped-around Electrode Epimysial Electrode Electrode Percutaneous Intramuscular Electrode

18 Surface Electrode The main goal of multilayer construction of the self_adhesive electrode is to provide a balanced most equally distributed stimulation current density over the whole electrode to prevent the skin from burns.

19 Nerve Cuff Electrodes This automatic spiraling electrode is designed to form to the natural shape of the nerve. The cuff electrode has four contracts that can be grouped together to create a stimulation that will activate groups of muscles.

20 Epimysial Electrodes This electrode has a tandem conductor close coiled lead wire from the connector, covered with a silicone tube (“closed helix”). The epimysial electrode terminates in a Pt-10 Ir disk mounted in a silicone backing reinforced with dacron.

21 Percutaneous Intramuscular Electrodes The intramuscular electrode has a stainless steel stimulating area wound around the distal end of the lead.

22 Cuff Electrode






28 Surface Electrode


30 Recruitment : Surface Electrode


32 Electric Field Between a Positive and Negative Electode

33 Nerve Excitation Model of myelinated fiber

34 Secondary Pulse Considerations

35 Excitation of Myelinated Nerve myelinated nerve fiber to a point source stimulation

36 Excitation of Myelinated Nerve



39 Motor response

40 Recruitment Regimen

41 Examples of: Commercial FES Systems

42 HandMaster Nathan Israel 1990 Electrodes: Surface (5) Commands: External Lateral & Palmar Grasp NESS Ltd. Available commercially

43 Bionic Glove (1996) Prochazka Univ. of Alberta Canada 1996 tenodesis Bionic Glove is OFF Bionic Glove is ON

44 FreeHand (?) Kilgore KL, Pekham PH Case Western Reserve University OH, USA 1998 Electrodes: (?) Epimysial Sensors: (?) Latera & Palmar Grasp NeuroControl Corp.

45 FreeHand (1999) Case Western Reserve University

46 FreeHand (2000) Case Western Reserve University

47 BION (USC-2000) G. Loeb Univ. Of Southern California 2000 Electrodes : Intramuscular Weight: 0.75 grams Dimentions: 3 mm x 28 mm Advanced Bionic Corporation (for investigation use only)

48 BION (USC-2000)

49 THANK YOU VERY MUCH For your Attention

50 Nerve Trunk Anatomy

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