# Influence of Electrode–Tissue Contact Area on Parameter Sensitivity in Electrosurgical Monopolar Soft Coagulation: A Multiphysics Finite Element Study

## TL;DR

This study shows how the contact area between an electrode and tissue affects the accuracy of simulations used in electrosurgery, especially for estimating tissue state during coagulation.

## Contribution

The paper introduces a multiphysics finite element model to analyze how electrode–tissue contact area influences parameter sensitivity in electrosurgical simulations.

## Key findings

- Electrical conductivity has the strongest influence on temperature development, especially at larger contact areas.
- Effective heat capacity significantly affects necrotic tissue volume formation, with sensitivity increasing for larger contact areas.
- Thermal conductivity has minimal impact on the simulation outcomes compared to other parameters.

## Abstract

Physics-based simulations are increasingly used to improve understanding of electrosurgical processes and to enable model-based estimation of tissue state when direct sensing is limited. The performance of such simulation-based virtual sensing approaches strongly depends on an accurate representation of the electrode–tissue interface. Despite its central role in electrical and thermal coupling, the influence of the electrode–tissue contact area has received limited attention in existing simulation studies. In this work, the influence of the electrode–tissue contact area on the sensitivity of key temperature-dependent tissue parameters was investigated for electrosurgical monopolar soft coagulation. Using a multiphysics finite element model under controlled boundary conditions, the sensitivity of maximum temperature development and necrotic tissue volume formation was analyzed with respect to varying contact areas and initial values of electrical conductivity, thermal conductivity, and effective heat capacity. The results demonstrate that parameter sensitivities are strongly contact-area-dependent. Electrical conductivity exhibits the most pronounced influence, particularly at larger contact areas, while thermal conductivity remains of minor relevance. In contrast, effective heat capacity significantly affects necrotic tissue volume formation, with increasing sensitivity for larger contact areas. These findings emphasize the importance of accurately accounting for electrode–tissue contact conditions in simulation-based analyses and clarify how contact-area-dependent sensitivities influence model-based tissue state estimation in electrosurgical coagulation.