Dimitar Stefanov

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Lecture 17

• Dimitar Stefanov

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Functional Neural Stimulation for Movement
Restoration (FNS)

• FNS activates paralyzed skeletal muscles by using
  an electronic stimulator, which delivers trains
  of pulses to neuromuscular structures.
• The basic phenomenon of the stimulation is a
  contraction of muscle due to the controlled
  delivery of electric charge to neuromuscular
  structures.

• FES systems is applied to restoration of
• Goal-oriented movements (movements at hand or
  arm)
• Cyclic movements (walking and standing movements).

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Block diagram of FNS model
The time delay between muscle stimulation and
muscle activation is called the neural dynamics.
Non-linear relationship between input activation
and generated joint torque (depends on the joint
angle, the joint velocity and acceleration).
Limb dynamics depends on the mass and inertia
characteristics of the limb, damping, elasticity,
stiffness.
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Upper extremity FES
A./ Classification, regarding the part of the
upper limb, which will be stimulated a./ FES of
hand motions b./ FES of elbow motions c./ FES
of shoulder motions.

• B./ Classification, regarding the source of
  control signals to trigger or regulate the FES
  patterns
• Shoulder control (Buckett et al., 1988)
• Voice control (Handa at al., 1982 NathanOhry,
  1990)
• Respiratory control (Hoshimiya et al., 1989)
• Joystick control (PeckhamKeith, 1992)
• Position transducers (Prochazka, 1993
  RebersekVodovnik, 1973).

• C./ Classification, regarding the number of the
  channels for FES patterns
• Systems with one- or two channels
• Multi channels systems.

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• D./ Classification of the systems, regarding the
  type of the electrodes
• FES systems based on surface electrodes
  (transcutaneous electrodes)
• FES systems based on implanted electrodes
  (percutaneous electrodes)
• FES systems based on implantable stimulators.

• Review of some systems for FES
• (LongMascirelli) the first grasping system
  (prehension and release) a spring for hand
  closure and electrical stimulation for of the the
  thumb extensor for release.
• 1984 (Rudel at al.) simple two-channel
  stimulation system and a shoulder activated
  position transducer (sliding potentiometer) at
  the neutral position of the potentiometer
  stimulation pulses stop
• First FES clinic - in Sendai (Japan) many
  persons are implanted with up to 30 intramuscular
  electrodes mainly for therapy, not to assist in
  grasping.

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Review of some systems for FES (continue) Japane
se FES systems for functional grasping, activated
by voice or suckpuff interface use of
pre-programmed EMG-based stimulation patterns
applied to subjects with lack of natural grasping
and elbow movements. 1989 Ben Gurion
University, Israel (Nathan) voice controlled
multichannel surface electrode system 12 bipolar
stimulation channels control of elbow, wrist and
hand function surface stimulation (doesnt allow
dexterity while grasping) problem need of
everyday mounting and fitting of the
system. Institut fuer Biokibernetic, Karlsruhe,
Germany recording of the EMG of weak muscle
amplifying the EMG and stimulation the same
muscle special means to prevent the positive
feedback (Hollaender at al., 1987)
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Review of some systems for FES (continue) The
Case Western Reserve University (CWRU) fully
implantable system hand opening/closing,
selection of the grasp, proportional control of
palmar and lateral grip joystick for control of
the stimulation signals preprogrammed control
joystick, activated by the contralateral
shoulder. The movement of the joystick activates
preprogrammed sequence of stimulation (the palmar
grip starts from the extended fingers and thumb,
followed by movement of the thumb and after that
by fingers flexion) 1992 (PeckhamKeith),
surgically modification of the grasp (pining some
joints and fixation of some tendons) two modes
grasp and hold, potentiometer for control of the
grip and additional EMG signal for to hold the
hand closed application at home for daily living
tasks.
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The Cleveland FES Center includes Cleveland VA
Medical Center, MetroHealth Medical Center, Case
Western Reserve University, and Edison
BioTechnology Center.
Some projects of the Cleveland FES Center
http//feswww.fes.cwru.edu/projects/index.htmbrie
fs
Implantable Stimulation, Telemetry, and
Transducer System for Neural Control
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The transducer, implanted in the wrist, allows
the individual to control grasp opening and
closing through voluntary movement of the wrist.
Under development new version of stimulator
up to sixteen channels of stimulation, one
implanted joint angle transducer and two channels
of myoelectric signal transduction. Myoelectric
signal obtained from arm or neck muscles will be
used to control various features of the grasp
and/or arm movements.
EEG-based Controller for FNS Hand Grasp Systems
(P. Hunter Peckham) Persons with C5 - C6 level
spinal cord injury. http//feswww.fes.cwru.edu/pr
ojects/phprsf.htm
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Bionic glove (University of Alberta, CA, Arthur
Prochazka), 1997 Neuromotion Inc.,
http//www.ualberta.ca/aprochaz/hpage.html
Hand opening and closing stimulator for C5-C6
quadriplegic people
Self-adhesive electrodes over certain muscles
elastic glove over the electrodes tightening the
glove causes electrical contact with the
electrodes user's wrist movements are sensed by
a transducer control a microprocessor based
stimulator.
Tremor suppression system, based on FES (A.
Prochazka).
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(No Transcript)
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Restoration of standing and walking
Ljubljana, Slovenija (Bajd, 1982, Gracanin, 1967)
Single-channel stimulation system applicable to
special group of patients with incomplete spinal
cord injury who can perform limited walking
without FES system. Multichannel system (1989)
FES system with at least four channels oriented
to patients with complete spinal cord injury, who
have preserved upper-body control stimulation of
the quadriceps locks the knee. Swing phase by
movement of the upper part of the body and using
of rolling walker hand- or foot switches are
used for flexion-extension alternation.
The Parastep Functional Electrical Stimulation
System Invented by Daniel Graupe (University of
Illinois at Chicago, EECS Dept.), produced by
Sigmedics, Inc. of Northfield, IL.
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The user controls the stimulation through
switches on the handgrips of the walker or
through a keypad on the stimulator unit standing
and sitting, taking right steps, taking left
steps, and increasing and decreasing the
electrical current.
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Cleveland FES center
Implantable standing FES systems
http//feswww.fes.cwru.edu/standingsystem/index.ht
ml
Studies that include investigational devices for
human use are registered with the Food and Drug
Administration (FDA).
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Eight channel fully implantable system.
Remotely controlled wireless microstimulators
BION Advanced Bionics Corporation
http//www.advancedbionics.com/products_frame.asp

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Gerald Loeb, a biomedical engineer at the
University of Southern California
The muscle wasting that afflicts many stroke
patients can lead to serious complications such
as thrombosis in bedridden patients.
http//www.newscientist.com/ns/19991211/newsstory1
.html
2 millimetres in diameter can be injected
directly into a muscle using a 12-gauge needle
once in place they are activated by a radio
signal from a coil worn by the patient deliver a
pulse of 30 milliamps for about 0.5 milliseconds.
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• Devised in a cylindrical shape with a stimulation
  electrode on each end, the microelectrodes
  contain their electronics in a hermetic glass
  capsule.
• Their physical dimensions are 2 mm in diameter
  and 16 mm in length.
• The electrodes are made of an activated iridium
  disk and an oxidized sintered tantalum slug which
  also serves as a power storage capacitor.
• The challenge of making the micro-stimulator
  consists of building a miniature, temperature
  sensitive electronic assembly and enclosing it
  into a slightly larger hermetic capsule made of
  high temperature glass.
• A custom CMOS chip, a rectifying diode and a
  chip resistor are mounted on a miniature
  two-sided printed circuit board, 0.18 mm thick.
• The components are connected by gold wire bonds
  and 0.15 mm wide gold-plated copper traces.

CUSTOM SILICON CHIP TECHNOLOGY FOR IMPLANTABLE
FES MICROSTIMULATORS Primoþ Strojnik, Joseph
Schulman, Philip Troyk,Gerald Loeb, and Paul
Meadows http//www.bme.med.ualberta.ca/fes/ifess
/page/p21.htm http//www.dinf.org/resna96/page116
.htm
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• The chip-PC board assembly is sandwiched between
  two ferrite half-cylinders.
• Two layers (200 turns) of 25 mm insulated copper
  wire wound on the ferrite represent a
  self-resonating receiving coil.
• The ends are attached to the PC board.
• A layer of a glob-top epoxy secures the
  components and the bond wires.
• Building the hermetic package involves making
  hermetic glass bead to metal seals to make
  electrode feed-throughs, creating contacts on the
  inside of the feed-through, and making a glass
  bead to glass capsule final seal.
• A miniature spring coil maintains a reliable
  connection between the inside feed-through
  contacts and the electronic assembly.
• Hermeticity better than 1x10-10 atm-cc/s was
  achieved in sealing the microstimulators.

CUSTOM SILICON CHIP TECHNOLOGY FOR IMPLANTABLE
FES MICROSTIMULATORS Primoþ Strojnik, Joseph
Schulman, Philip Troyk,Gerald Loeb, and Paul
Meadows http//www.bme.med.ualberta.ca/fes/ifess
/page/p21.htm http//www.dinf.org/resna96/page116
.htm
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• The BION produces asymmetric biphasic
  constant-current pulses.
• The BION receives power as well as stimulation
  commands via magnetic link from an external coil
  that is worn by the patient.
• An amplitude modulated 2 MHz carrier powers and
  transfers stimulation data to the
  micro-stimulator and provides the basic clock for
  the digital part of the micro-stimulator
  circuitry.
• The microstimulators are addressable. One coil
  can control up to 255 uniquely addressable BIONs.

http//www.biontech.org/about/what_is_a_bion_01.ht
ml
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• Problems, which limit the effectiveness of the
  FES systems
• Fast fatigue
• Reduced torques generated through FES in
  comparison with central nervous system control
• Osteoporosis and stress fractures.

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Hybrid Assistive systems (HAS)
Integration of two assistive systems FES system
and external mechanical orthosis.

• Advantages
• Partial mechanical support
• Parallel operation of the biological and
  mechanical system
• Sequential operation of the biological and the
  mechanical system.