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Non-Invasive Induction Link Model for
Implantable Biomedical Microsystems:
Pacemaker to Monitor
Arrhythmic Patients in Body Area
Networks
Prepared by:
Anum Tauqir
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Outline
 Background
 Problem Statement
 Motivation
 Mathematical Model
 Equivalent Circuits
 Equations
 Simulation Results
 Conclusion
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Background
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 Medical Implants aim to:
 replace missing body parts or
 deliver medication, monitor body functions, or provide support to
organs and tissues.
 Most widely implanted device:
 Pacemaker
 monitor patients with heart related issues
 Most commonly occurring is arrhythmia
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Arrhythmia
 an abnormal heart rhythm, due to changes in the
conduction of electrical impulses through the heart.
 Pacemakers:
 use low-energy electrical pulses to overcome this abnormality.
 They create forced rhythms according to natural human heart
beats, to let the heart to function in a normal manner.
 consists of a small battery, a generator and wires attached to the
sensor to be inserted into the patients heart.
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Working of Pacemaker
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Problem Statement
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 To cater for arrhythmia:
 generated pulses carry sensed information regarding different
events occurring inside the heart to the doctor
 processing and transmission of data,
 create a strain on the battery of a pacemaker to consume huge amount
of power that ultimately;
 depletes the sensor and hence becomes unable to further carry any
informational data.
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Motivation
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 Induction technique is presented to:
 recharge the sensors battery, implanted inside a pacemaker to
avoid early depletion
 Technique focuses on enhancing:
 voltage gain
 link efficiency
 Two equivalent circuits:
 Series tuned primary circuit
 Series tuned primary and parallel tuned secondary circuit
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Mathematical Model
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Induction Link
 Primary Circuit
 powered by a voltage source
 Secondary Circuit
 Source generates magnetic flux in order to induce power at
secondary side, implanted inside human body.
 Interface
 skin acts as an interface or a barrier between the two circuits.
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Induction Link Parameters
 Coupling Co-efficient (k)
 degree of coupling between the two circuits.
 enhances the link efficiency
 In WBANs for body tissues safety:
 k < 0.45
 Voltage Gain (Vout / Vin)
 ratio that, indicates an increase in the voltage at the output side in
relative to the voltage applied at primary side
 Link Efficiency (η)
 ability of transferring power from primary side to secondary side in
an efficient manner.
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Equivalent Circuits
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Series Tuned Primary Circuit (STPC)
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 a capacitor is connected in series at primary side.
 as, only a small amount of voltage induces because of a low
coupling factor of 0.45 so,
 a series tuned circuit is used in order to:

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induce sufficient amount of voltage to the secondary coil
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Series Tuned Primary and Parallel
Tuned Secondary Circuit (STPPTSC)
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 capacitor C2p is connected in parallel at secondary side
 as, the sensors implanted inside a human body operate under low
frequencies.
 parallel capacitor let the circuit to act as a low pass filter
which,
 allows low frequencies to pass through and,
 blocking the higher frequencies thereby,
 preventing damages to body tissues
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Model Parameters
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Parameter
Value
Operating frequency
f = 13.56 MHz
Primary coil
L1 = 5.48 μH
Secondary coil
L2 = 1 μH
Parasitic resistance of the
transmitter coil
RL1 ≃ 2.12 Ω
Parasitic resistance of the receiver
coil
RL2 ≃ 1.63 Ω
Load resistance
Rload = 320 Ω
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Equations
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Voltage Gain
For STPC
where,
For STPPTSC
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Link Efficiency
For STPC
where,
For STPPTSC
where,
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Simulation Results
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Voltage Gain of Series Tuned Primary Circuit
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Link Efficiency of Series Tuned Primary
Circuit
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Voltage Gain of Series Tuned Primary and
Parallel Tuned Secondary Circuit
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Link Efficiency of Series Tuned Primary and
Parallel Tuned Secondary Circuit
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Conclusion
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