Electrosurgical Cautery Thermal Spread Simulator

Electrode

Generator power 40 W

Electrode tip size 2

Press and drag on the tissue block to apply the electrode. Cut mode arcs a small, high-power spot that vaporises a groove; Coagulate mode spreads a gentler, wider heat to seal vessels without cutting.

Live readout

Peak tissue temp

37 °C

Char coverage

Vessels sealed

0 / 2

How it works

The electrode drives radio-frequency current through the tissue; resistive (Joule) heating deposits power in a small volume under the tip, and that heat then diffuses outward. The grid solves the 2D heat equation explicitly at every frame:

∂T/∂t = D·∇²T − k·(T − T_body) + Q(x,y,t)

D  = thermal diffusivity of tissue
k  = perfusion/convective cooling toward T_body ≈ 37°C
Q  = electrode power deposited under the tip,
     weighted by distance from the contact point

Tissue response is threshold-driven, not linear — the same physics real electrosurgeons watch for:

~45–60 °C — hyperemia, reversible if it stops here.
~60–70 °C — protein (collagen) denaturation: the tissue visibly whitens. This is the coagulation/sealing window.
~100 °C — intracellular water flashes to steam; the tissue desiccates.
>150 °C — carbonisation (char); charred tissue is a poor conductor, so power stops coupling efficiently and further cutting stalls.

Cut mode concentrates power into a small, high-intensity spot that reaches vaporisation almost instantly, mechanically parting tissue (the block visibly grooves and blackens). Coagulate mode spreads a lower, wider power over a longer dwell so more tissue volume passes through the 60–70 °C denaturation window without ever reaching char — the goal when sealing a bleeding vessel. Hold the tip over a red vessel marker in Coagulate mode; if it stays in the sealing window long enough it turns solid (sealed). Overheat it past ~160 °C and it chars instead — a real failure mode called an inadequate or "burnt" seal.

Healthy / hyperemic Coagulated (sealed) Desiccated Charred / cut

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