SINUSOIDAL CURRENT
Dr. Amal Abd El Baky,
LOGANATHAN CHANDRASEKAR
353 RHPT – 1435 – 1436H – 1st SEM
Lecture outline
2

Physics and principles of sinusoidal current

Characteristics, Physiological & Therapeutic
effects of sinusoidal current

Uses and dangers of sinusoidal current

Parameters &technique of application of
sinusoidal current
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Sinusoidal Current
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Lecture objectives
3
At the end of lecture the student is able to




Define and outline the principle & production of
sinusoidal current.
List the Characteristics, physiological
&Therapeutic effects, uses & dangers of
sinusoidal current.
Select the appropriate sinusoidal current dose.
Demonstrate the Parameters & application of
sinusoidal current.
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Sinusoidal Current
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Definition & Physics
4
Definition:



A sinusoidal current is an evenly alternating sine wave
low frequency current with a frequency of 50 HZ
It can be produced from the mains by reducing the
voltage to 60-80 V with a step down transformer.
Patient feel tingling sensation
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Sinusoidal Current
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Sine waves
Sine waves are characterized by the amplitude and
period. The amplitude is the maximum value of a
voltage or current; the period is the time interval for
one complete cycle.
20 V
The amplitude (A) of
this sine wave is
20 V
The period is
15 V
0V
50.0 s
A
10 V
t (s)
25
0
-10 V
-15 V
T
-20 V
5
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37.5
50.0
6

It can be used as surged or unsurged currents.

It is usually surged to cause a RHYTHMICAL MUSCLE
CONTRACTION.
Surged sinusoidal current
Sinusoidal current
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Characteristics of a Sine Wave

The length of time it takes to complete one cycle or
conversely the number of cycles that occur in one
second.



The maximum and minimum voltage or current swing


7
Period
Frequency
Amplitude
Peak-to-peak amplitude
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Period, T
The period of a sine wave can be measured
between any two corresponding points on the
waveform.
8
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Frequency, f
Frequency ( f ) is the number of cycles that a sine
wave completes in one second.
Frequency is measured in hertz (Hz).
If 3 cycles of a wave occur in one second, the frequency is
3.0 Hz
9
1.0 s
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Amplitude, A
The amplitude of a sine wave is only measured from the center to
the maximum point.

10
Peak amplitude

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Peak-to-Peak amplitude
Sinusoidal Current
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Generation of a sine wave
Sinusoidal voltages are produced by ac generators and
electronic oscillators.
When a conductor rotates in a constant magnetic field, a
sinusoidal wave is generated.
C
N
D
B
S
A
B
C
D
A
Motion of conductor
11
Conduc tor
B - When the loop is moving perpendicular
to the lines of flux, the maximum voltage is
induced
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A - When the conductor is moving
parallel with the lines of flux, no
voltage is induced.
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Physiological & Therapeutic effects of
sinusoidal current
Tetanic muscle
contraction and
tingling sensation due
to motor & sensory
nerve stimulation
Rhythmic muscle
contraction by surged
mode helps in edema
reduction
Enhance blood flow
and intramuscular
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Pain relief via sensory
stimulation by the
same mechanisms of
TENS
Reduction of edema
and inflammatory
exudate by unsurged
mode
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Dangers
13

Burn:
a. Overdose( high intensity, long duration)
b. Bare metal electrode on the skin.
c. Metal in the path of the current.
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
Shock:
Sudden Increase or decrease of the current
intensity.
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
Pain :
a.
Overdose.
b.
Small raised edge.
c.
Tiny cut not insulated.
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Technique of application
16



Sinusoidal current can be applied in the same way
as other low-frequency currents by means of
electrodes and pads.
However, because of the marked sensory stimulation
this current is often applied to large areas and
rarely used for local muscle stimulation.
So it is applied either through large pads or water
baths.
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For pain it can be used in continuous mode at intensities
close to the limit of tolerance and increase the current with
accommodation. Application will be done for 5 min and
repeated with insufficient response.
For reduction of oedema and to increase the limb
circulation surged sinusoidal current is suggested. causing
regular rhythmical muscle pumping actions.
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Application – Procedure / Method
18

Put the patient in a comfortable position.

Explain the patient the purpose of the treatment.

Select the setting on the machine for a sinusoidal
current with a pulse duration of 10 ms, and a
frequency of 50 Hz.
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
Connect the leads to the metal electrode and to the
machine.

The pads should be moistened evenly.

Explain the sensation to the patient “tingling sensation”

Examine the area under both active and indifferent
electrodes for any cut and if insulate with Vaseline.
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

Bandage the active electrode on the target tissue
with indifferent one on the foot.
Increase the intensity gradually till the patient
experiences tinging sensation under the active
electrode. The response decreases slowly after2030 sec then increase the intensity gradually.
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
Continue this. After 4 minutes see if the stinging is
adequate there is immediate marked numbness to
touch and pressure, and all pain in the treated area
is lost.

If there is no numbness or partial, repeat for 4 min.

The erythema and numbness persists for about 1 h.
353 RHPT
Sinusoidal Current
7/1/2016