Transcript NeuroEngineering:Chapter 18

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Minhye Chang
Proceedings of the IEEE
Introduction
Evolution
Battery-Powered BION
System
Applications
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* Low-level electrical current to
nerves or reflex centers
* Triggered by
• single switch(open-loop)
• neuronal activity(closed-loop)
* Limb loss applications
• Reduce phantom pain
• Restore functional movement
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Introduction
Evolution
System
Applications
* Provide both stimulating and sensing capabilities
* Be fully implantable
* Be minimally invasive
* Have real-time communication capability
* Practically unlimited number of stimulation and
sensing channels
* Function w/o external equipment or
interconnected leads btw components
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Introduction
Evolution
System
Applications
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Extensive surgery
•20-plus channel Nucleus FES22 requires more than 15h of surgery
Infection of Large Continuous Implant Surfaces
•Bacterial infection spread to the entire implant.
•The only remedy is to explant the entire system.
RF Powered Device Problems
•Maintaining proper orientation of the power transmitting antenna
•The discomfort of wearing an antenna and a battery powered
transmitter
Lack of Coordinated Sensors and Stimulators
•Other than demand pacemakers, very few attempts to use
implantable sensors
Extensive Advanced Planning
•Each condition usually requires a unique sensor system
•The number of channels, the type of sensors and signal conditioning, and etc.
Introduction
Evolution
System
Applications
* As either stimulators or sensors
* Minimally invasive implantation
* Wireless, real-time bidirectional
communications
* Flexibility and functional expandability
w/o leads
* A large number of channels
* Self-powered operation
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Introduction
Evolution
System
Applications
Battery-Powered
• To improve patient
acceptance
• To increase the
reliability
• Operate for more than
ten years
RF-powered
• Allow instantaneous
control
• Prevent electrostatic
discharge
• Need to wear an
external coil
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By Quallion. Capacity of 10mWH,
operating at a voltage of 3.6V
Introduction
Evolution
System
Applications
* For urinary incontinence
* The 1st BION to have twoway telemetry
* Very short time for
* Wireless
* Fully implantable
* Data processing for sensed
signals
synchronization
* Lack of sensing capabilities
* Slow communication
response time
* Rechargeable
* Long term immersion
weakens ceramic 
improve longevity
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Introduction
Evolution
System
Applications
* Improved IC
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Increase the compliance voltage of the RF-powered
microstimulator
• Modified the demodulation circuit
* Combining the IC and the ferrite
• Longer and more efficient coil in receiving energy from the
ac magnetic field
* Ceramic case
* Internal capacitor
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Prevents continuous direct current from flowing into the
tissue
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Introduction
Evolution
System
Applications
* Defibrillator protection
• Prevents damages from static electricity in the
operating room
* Eyelet
• Enables a simple removal within about a week or more
* Insertion System
* Human experiments
• 42 RF microstimulators in six stroke patients
• Ultrasonic and magnetic resonance image viewing
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Introduction
Evolution
System
Applications
* Stimulating lead system failure
• Stimulation amplitude and low current range was
unstable
* Automatic tuning of AC powering coils
• Need a very precise tuning frequency in coil to save
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battery power
A crystal controlled oscillator and a bank of about
eight capacitors in the external control unit
* Hermetic and electrolytic corrosion free braze
joints
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Introduction
Evolution
System
Applications
* Arm coil system
• Microstimulators btw the wrist and elbow
• To produce a magnetic field, two coil pairs are
connected in series
* Clinicians automatic test system
• The fitting notebook station an automatic
microstimulator tester
• Test regime will verify nearly every connection
in the microstimulator
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Introduction
Evolution
System
Applications
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Introduction
Evolution
System
Applications
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• Communication and control hub
• External MCU: a few controls
accessible to the patient
• Implantable MCU: small patient
control unit (PCU)
Introduction
Evolution
System
Applications
* Transmits and receives data up to 850 BPBs within 1/100s
* Basic user interface
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System ON/OFF control, alarms, program selection and limited
parameter control
* During fitting, enables the setup and the coordination
* Manages the recharging subsystem
* Safety mechanisms
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Emergency STOP button
When BPB overheats or overcharges
* Stores patient usage data and the approximate location
of BPBs
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Introduction
Evolution
System
Applications
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• Allows the clinician to configure
and test
Introduction
Evolution
System
Applications
* During the fitting, CP & MCU facilitate measurement and
storage of the stimulation and sensor calibration parameters
* During the stand-alone mode, essential information is stored
in the MCU
* Clinician’s programmer
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Gather basic personal information
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Specify the activity sequences
Establish the stimulation range and allow selection of the stimulation
parameters
Gather the trigger information
Compose the Finite State Machine functions
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Introduction
Evolution
System
Applications
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• Place the coil close to the area
• Battery
 Depend on the frequency and
stimulation levels
 Run in 1 to 8 days
• Charging for about 5 to 20 min
per day
Introduction
Evolution
System
Applications
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• Transmits only power
• Each BPB
 Charging and battery status
Introduction
Evolution
System
Applications
* 12-kHz signal to generates a magnetic field
* MCU
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Determines which BPB to be charged and when to charge
Indicates to the patient where the coil must be moved
Selects the most discharged device
* Temperature sensor that stops the process
when the external coil overheating
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Introduction
Evolution
System
Applications
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• Safety feature when
 Undesired manner
 No access of the
patient to control unit
• Magnet is positioned
 On the body  holds
off the stimulation
 On the other part 
stimulation turns on
• Small, light weight,
very strong
magnetic signal
Introduction
Evolution
System
Applications
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Introduction
Evolution
System
Applications
* Single-channel, constant-
current, charge-balanced
stimulator
* Capacitance-coupled output
prevents direct connection
btw battery and tissue.
* Pulse amplitude, width, and
frequency
* Triggering events
* Dipole antenna
* Crystal-controlled
transmitter, receiver, &
digital processing unit
* Digital processing unit
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Corrects errors in data and
communication
Decodes the MCU commands
Generates the responses to
the MCU
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Introduction
Evolution
System
Applications
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Stimulation and/or
sensing control data
Forward error
correction (FEC) bits
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Information to
MCU
FEC for 1 or 2bit
errors
For frame synchronization and frame control data
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Introduction
Evolution
System
Applications
* 10-mW-hr rechargeable
lithium-ion battery
* Recharging via 127kHz
magnetic link
* Provide 100 hours of
operation
* Deep discharge  lifetime
of more than ten years
* Miniature magnetic sensor
* Temperature sensor for
terminating charging
* Battery safety circuitry
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Overvoltage, overdischarge, and
overcharging
* For themselves for
maximum charging
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Introduction
Evolution
System
Applications
* “Oscilloscope mode” during
* Along the axial dimension of
* Data analysis
* 400~900 mmHg
* AC/DC coupled
* Altitude changes 
fitting
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Count pulses: accumulated
pulses every 10ms
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Rectify and integrate every 10
ms
the BPB
reference sensor in the MCU
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Introduction
Evolution
System
Applications
* Distance btw two BPBs
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Intensity of the received magnetic
field
One BPB as a transmitter, and
other BPBs as a receiver
Receiver BPB detects and
measures the signal strength
No limit to the number of BPB
receivers
Measure distances btw 1~20cm
* As a safety mechanism
* Accurate to within 0.33˚C
* Range 16~50 ˚C
* Taken once per second
* 8 parallel systems whose
frequencies are around 127kHz
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Introduction
Evolution
System
Applications
* Minimally invasive
procedure
A: Probe Electrode
B: Dilator
C: Sheath
D: Ejection Tool
E: 3ml Syringe
• 1st test during the
implantation
• 2nd test right after the
implantation
• 3rd test one week after
implantation
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Introduction
Evolution
System
Applications
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As a stimulator, biopotential signal sensor, goniometry sensor, pressure or
temperature sensor
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Multiple BPBs; up to 850 BPBs
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Near motor-points or nerves of muscles in the arm, forearm, and hand
To extend the arm and forearm, and open the hand to grasp an object
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Sensing of the muscle activities acts as triggers to other BPBs to stimulate
the motor-points
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As goniometry sensors and pressure sensors
Standing, ambulation, swallowing, bladder control, and respiration
Measuring pressure and triggering motor-point or stopping a FES sequence
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At the heel, the buttock, or hand
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Introduction
Evolution
System
Applications
* As biopotential sensors
* Inserted in the “stump”
* Pick up motor nerve signals to
control movement
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Introduction
Evolution
System
Applications
* Voluntary motion is regained
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By monitoring the motor cortex
By feeding back sensed response signals to the sensory cortex
* Cortical interface device (CID)
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Base unit implanted in the skull monitors up to several hundred electrodes
Electrode arrays placed on the sensory or motor cortices
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Introduction
Evolution
System
Applications
* CID base unit
• Equivalent to a group of sixty-four BPBs
• Sixty-four biopotential sensing modules
• Either unipolar or bipolar
• Same technology developed for the BPB
* Sensing electrode array
• Include signal processing capability like biopotential sensing
module in the BPB
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same stimulation electronics like the BPB stimulation module
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Introduction
Evolution
System
Applications