Waveforms of Therapeutic Currents

Original Editor - Rafet Irmak

Top Contributors - Rafet Irmak and Rachael Lowe

Waveforms of Therapeutic Currents

Therapeutic currents are, special electric currents that are applied to human body for healing the body. Generally these are defined by using voltage-time chart of the current which can be seen in the oscilloscope screen. This page summaries the waveform of common therapeutic currents[1].

Fundamental Terms

Oscilloscope

An ossiloscope is an instrument which is used to observe voltage changes during time in electric circuits.

Signal Generator

A signal generator is an instrument which generates electrical signals at given waveform, frequency and amplitude. Electrotherapy equipment is a kind of signal generator which generates therapeutic signal waveforms in safe frequency and amplitude.
Figure 1: Ossiloscope and signal generator

Frequency

Frequency is a term which describes how many times a waveform repeat it self per second by signal generator.

A 100 Hz Sine Wave

Figure 2: Signal generator settings for sine wave at 100 Hz frequency and 1V peak amplitude.
Figure 3: Ossiloscope screen shot for sine wave at 100 Hz frequency and 1V peak amplitude.

A 500 Hz Sine Wave

Figure 4: Signal generator settings for sine wave at 500 Hz frequency and 1V peak amplitude
Figure 5: Osiloscope screen shot for sine wave at 500 Hz frequency and 1V peak voltage amplitude.

A 1000 Hz Sine Wave

Figure 6: Signal generator site for sine wave at 1000 Hz frequency and 1V peak amplitude
Figure 7: Osciloscope screen shot for sine wave at 1000 Hz frequency and 1V peak voltage amplitude.

Peak Amplitude

The term peak amplitude defines the highest positive or negative value of a waveform. In therapeutic currents peak amplitude generally defines the highest value of the voltage during time.

Peak to Peak Amplitude

The term peak to peak amplitude defines the amplitude between the highest negative to highest positive value. Peak to peak amplitude of a sine wave is equal to two times peak value of a sine wave.

Mean Amplitude

The term mean amplitude defines mean value of a waveform. In therapeutic currents mean amplitude is a quantity in terms of voltage. Peak amplitude of a sine wave has different mean amplitude value. Mean amplitude of a sine wave is equal to 0.637 x Peak Amplitude.

Peak and Mean Amplitude of 100 Hz and 1 Volt Sine Wave

Figure 8: Signal generator parameters for a sine wave at 100 Hz and 1V.
Figure 9: Osciloscope screen shot for peak and mean amplitudes of a 100 Hz 1 Volt sine wave.

Peak and Mean Amplitude of 1000 Hz (1KHz) and 10 Volt Sine Wave

Figure 10: Signal generator parameters for a sine wave at 100 Hz and 10 V.
Figure 11: Osciloscope screen shot for peak and mean amplitute of a 100 Hz, 10V sine wave.

Peak and Mean Amplitude of 1000 Hz (1KHz) and 20 Volt Sine Wave

Figure 12: Signal generator parameters for Peak and mean amplitude of a sine wave  at 100 Hz  and 20V.
Figure 13: Osciloscope screen shot for peak and mean amplitute of a 100 Hz, 20V sine wave.

Square Waveform

Square waveform is a common therapeutic waveform. Interrupted galvanic current and TENS are forms of Square waveform. The main parameter of a square waveform is duty cycle. It defines the time ratio when voltage is higher or lower then zero and when voltage is equivalent to zero.

50% Duty Cycle Square Waveform

Figure 14: Signal genrator settings for 10 V, %50 duty cycle, square waveform
Figure 15:  Osciloscope screen shot for 10 V, 50% duty cycle, square wave

20% Duty Cycle Square Waveform

Figure:16 Signal generator settings for 10 V, 20% duty cycle, square waveform
Figure 17:Osciloscope screen shot for 10 V, 20% duty cycle, square wave

50% Duty Cycle Square Waveform

Figure 18: Signal generator settings for 1 V, 100 Hz 50% duty cyle, square waveform
Figure 19: Osciloscope screen shot for 1V, 100 Hz, 50% duty cycle, square waveform

75% Duty Cycle Square Waveform

Figure 20: Signal generator settings for 1 V, 75% duty cycle, square wave form
Figure 21: Osciloscope screen shot for 1V, 100Hz, 75% duty cyclesquarewaveform

References

  1. Rafet IRMAK Ahsen IRMAK . Elektroterapi Atlası 1: Fizyoterapi Öğrencileri için Dalga Formları, Cervical, Thoracal ve Lumbosacral Bölge Elektrot Yerleşimler Mevlana Üniversitesi, 2013