Electrosurgical Unit

Overview

An electrosurgical unit cuts and coagulates tissue with high-frequency electrical current instead of a blade. When current is concentrated at the fine tip of an active electrode, the tissue right at the tip heats so fast that cells boil and part, a clean cut, while a different waveform heats more gently to seal bleeding vessels. The frequency is kept high, hundreds of kilohertz, so the current passes through the body without stimulating nerves or muscle the way mains-frequency current would. It is one of the most common tools in any operating room.

The core is the RF Generator Board, which produces and controls the waveform. Current leaves through the Output Ports to the surgeon's pencil and returns through the Return Electrode pad. The surgeon selects cut or coag with the Foot Pedal, reads settings on the Display Panel, and the Cooling System system and Power Supply keep the generator running through long cases.

How it works

Power conversion happens on the RF Generator Board. A DC rail from the Power Supply feeds an inverter built from an IGBT Power Module stage, which switches it into a high-frequency square wave. That wave drives the Output Transformer, a ferrite transformer that steps the voltage up to the hundreds, or, for spray coagulation, thousands, of volts needed and isolates the patient from mains. An Microcontroller shapes the waveform: a continuous wave for pure cutting, a bursty low-duty wave for coagulation, and a blend in between.

Holding the effect steady is a closed loop. As tissue dries and chars, its impedance climbs, so the Output Current Sensor feeds the controller, which adjusts drive to keep delivered power on target rather than letting the cut stall or run away. Safety rests on the return path: the Dispersive Pad spreads the returning current over a wide skin area so it does not burn, and the Contact Quality Monitor continuously measures pad impedance, disabling output the moment the pad lifts. The surgeon activates with the Foot Pedal or the handpiece switch read at the Handpiece Jack, adjusts power on the Display Panel, and the Blower Motor in the cooling path carries heat off the power stage during sustained activations.