Unipolar sine surge (USS) currents are modern solutions in electrotherapy. This physiotherapy procedure combines the benefits of using unidirectionally modulated medium-frequency currents with the effects of electrode polarization.
The development of a microprocessor field in electronics made generating a unipolar current possible. Until now, generating such a complex and repeatedly modulated shape of the current was relatively challenging.
Medium frequency currents – characteristics
Medium frequency currents are those with frequencies ranging from 1000 to 10000 Hz. Applying this kind of current carries many benefits. And those are:
- considerably better tolerance by patients than a low-frequency pulse or a direct current,
- the confirmation of deeper tissue penetration due to the resistive-capacitive nature of tissue resistance.
- less risk of causing skin damage (e.g., burns).
Remember: Simultaneously with an increase in the frequency of the current, the capacitive resistance of tissues declines!
Unipolar current – indications
When should the unipolar current be applied?
- while dealing with acute or chronic pain,
- for iontophoresis and galvanization treatments,
- while treating circulation disorders,
- to accelerate the healing of oedemas and hematomas,
- for muscle strength training,
Unipolar Sine Surge (USS) – parameters and shape of the current.
The USS current is a series of impulses that appear one after another. Frequency modulation is used to prevent a body from adapting.
The first modulation is the superimposition of a rectangular waveform with a 40 kHz frequency, modulated with a frequency of 4 kHz and a duty factor of 50% on the direct current. This waveform is then modulated with a sinusoidal envelope with an adjustable frequency of 1 to 100 Hz.
Given that, this frequency can vary according to a frequency deviation parameter. Deviation can take on values from 5 to 200 Hz and is subjected to frequency changes that are compatible with built-in training programs. These programs have a duration of a few to several seconds, with rise time, fall time, and generation phases of the set frequency.
Unipolar Sine Surge (USS) — procedure
USS treatments fall under the same procedures and rules as standard electrotherapy therapies.
Also, a unipolar sine surge is often used in iontophoresis treatments. An article about iontophoresis is available in the article:
Both the indications and parameters of the currents are very similar to those of low-frequency current therapy.