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An Introduction to
Functional Electrical Stimulation
Presented by:
Fereshteh Lagzi
Presentation Agenda
Introduction
History of FES
FES systems main components
Electrodes
Muscles, Neural and electrical stimulation
Examples of Commercial systems
ES applications
‫‪FES system’s main components‬‬
‫اراده و هوشياري كاربر‬
‫فرامين ارادي‬
‫منبع تغذيه‬
‫پردازشگرو كنترلگرفرامين‬
‫واسط كاربر‪ -‬سيستم‬
‫فيدبك سيستم‬
‫پارامترهاي تحريك‬
‫تحريك كننده‬
‫اتصاالت الكترودها‬
‫الكترودها‬
‫تحريك‬
‫انقباض عضالني‬
‫حسگر نيرو‬
‫حركت‬
‫موقعيت مفصل‬
‫حسگر موقعيت‬
Muscles
Skeletal Muscle fibers:
neural ans electrical Stimulation
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
Muscle
Pulse amplitude
Nerve
Pulse width
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
Types of Electrodes
Polarizable electrodes:
Ag
Nonpolarizable electrodes:
Ag_ AgCl
Electrode- Tissue Behavior
Electrode- Tissue Behavior
Electrode Operating Characteristics
Electrode Operating Characteristics
Electrode Operating Characteristics
Electrode Operating Characteristics
Current wave forms
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
Electrode Placement
(1)
(1)
(2)
(3)
(4)
(5)
(2)
(3)
(4)
Skin Surface Electrode
Epimysial Electrode
Nerve Cuff Electrode
Percutaneous Intramuscular Electrode
Intramuscular Electrode
(5)
Electrodes
Nerve Cuff Electrode
Wrapped-around Electrode
Wrapped-around Electrode
Epimysial Electrode
Electrode
Electrode
Percutaneous Intramuscular Electrode
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.
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.
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.
Percutaneous Intramuscular Electrodes
• The intramuscular electrode has a
stainless steel stimulating area
wound around the distal end of the
lead.
Cuff Electrode
Cuff Electrode
Cuff Electrode
Cuff Electrode
Cuff Electrode
Cuff Electrode
Surface Electrode
Surface Electrode
Recruitment : Surface Electrode
Recruitment : Surface Electrode
Electric Field Between a Positive and
Negative Electode
Nerve Excitation
Model of myelinated fiber
Secondary Pulse Considerations
Excitation of Myelinated Nerve
myelinated nerve fiber to a point source stimulation
Excitation of Myelinated Nerve
Excitation of Myelinated Nerve
Excitation of Myelinated Nerve
Motor response
Recruitment Regimen
Examples of:
Commercial FES Systems
HandMaster
Nathan
Israel
1990
Electrodes: Surface (5)
Commands: External
Lateral & Palmar Grasp
NESS Ltd.
Available commercially
Bionic Glove (1996)
Prochazka
Univ. of Alberta
Canada
1996
tenodesis
Bionic Glove is OFF
Bionic Glove is ON
FreeHand
(?) Kilgore KL, Pekham PH
Case Western Reserve University
OH, USA
1998
Electrodes: (?) Epimysial
Sensors: (?)
Latera & Palmar Grasp
NeuroControl Corp.
FreeHand (1999)
Case Western Reserve University
FreeHand (2000)
Case Western Reserve University
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)
BION (USC-2000)
THANK YOU VERY MUCH
For your
Attention
Nerve Trunk Anatomy