Which diathermy mode is characterized by a cutting instrument using a sinusoidal non-modulated waveform?

The cutting mode of diathermy is characterized by the use of a sinusoidal non-modulated waveform, which efficiently generates high-frequency current to cut tissue. This mode allows for precise incisions by creating a stream of electrical energy that heats the tissue sufficiently to vaporize or disrupt it. Unlike other modes of diathermy, which may focus more on achieving hemostasis or reducing tissue dryness, the cutting mode prioritizes the sharp and effective separation of tissues.

In coagulation mode, the waveform is modulated to achieve a slower heating effect that promotes clotting and sealing of blood vessels rather than cutting. Dessication mode involves the application of heat to remove moisture and thus would not utilize a pure cutting wave. Blend mode combines aspects of both cutting and coagulation but still does not utilize a pure non-modulated sinusoidal waveform solely for cutting purposes. Therefore, the unique characteristic of the cutting mode, defined by its specific waveform, distinctly positions it as the correct choice for this question.