Effect of superhydrophobic microstructures on the heat transfer performance of surgical electrode: Droplet and bubble dynamics investigation

Severe thermal damage to biological tissue resulting from active electrosurgical electrodes often causes corresponding tissue adhesion and reduces cutting efficiency during the surgery process. The introduction of superhydrophobic surfaces has been proven to be an effective approach for thermal damage reduction and anti-adhesion. However, the heat transfer phenomenon, especially the effect of superhydrophobic microstructures on the electrodes, has not been fully illustrated. In this study, we investigated the water droplet behavior on a superhydrophobic micro-channel (SHMC) surface and bubble dynamics of identically structured electrodes under thermal and thermoelectric coupling fields. The thicker vapor film, caused by the trapped air within microstructures on the SHMC surface, resulted in a reduced evaporation speed of droplets. Moreover, under the thermo-electric coupling field, the SHMC surface exhibited notable three-stage bubble evolution compared to the flat surface: Enhanced bubble coalescence in the initial stage, attributed to accelerated single bubble growth rates; Surface-wide nucleation with subsequent adhesion and merging events in the transition stage; Sustained tip-encapsulation in the stable stage, resulting from increased bubble generation frequency and extended departure diameters. The vapor film that continuously encapsulates the microstructures alters the heat transfer mode from thermal convection to thermal conduction and radiation, inhibiting the heat transfer of the SHMC surface. Consequently, the heat dissipation performance is enhanced, reducing the thermal damage to the biological tissue. These findings provide support for understanding the thermal damage-reducing mechanism of superhydrophobic surfaces on electrosurgical electrodes.