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Non-Invasive Induction Link Model for Implantable Biomedical Microsystems:

Pacemaker to MonitorArrhythmic 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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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.

Arrhythmia

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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:

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 ParametersParameter 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

For STPPTSC

where,

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Link Efficiency

For STPC

For STPPTSC

where,

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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