Study On Electrode-sticking Tissue Interface Bonding Mechanism And Anti-sticking Electrode For Electrosurgical Instruments

As a major clinical concern,the adhesion of tissue to electrodes has been seriously hindered the application of electrosurgical unit in minimally invasive surgery.At present,most previous research work focused on the anti-sticking measures of active electrodes including surface modification and ancillary equipment,while few efforts have been made to the behavior and mechanism of tissue sticking,then causing that most anti-sticking measures cannot work effectively in clinic currently.Therefore,it is very necessary to investigate the mechanism of tissue sticking upon electrodes systematically,which would provide valuable insight to the development of effective anti-sticking measures,promote the application of electrosurgical unit in minimally invasive surgery,and enrich the basic theory of mechanical surface/interface discipline.In this study,the adhesion behavior of tissue to electrode was studied under three conditions,electrosurgical cutting test condition,heat-adherence test condition,and arc-discharge & heat-adherence test condition,aiming to understand how the tissue adheres to active electrode during electrosurgery.The interface of sticking tissue and electrode was examined by means of many methods such as microscopic morphology analysis,element map scanning,nano-indentation hardness measurement and pull-out test.Based on the obtained bonding mechanism of sticking tissue with electrode during electrosurgery,an anti-sticking electrode was developed by coating tungsten with high melting point on the surface of 304 stainless steel electrode.The main results and conclusions were drawn as below.1)High-frequency electric field played an extremely important role in the formation and bonding of sticking tissue upon active electrode during electrosurgery.Under heat-adherence condition,the sticking tissue was formed by nano-particles pillng up,and then has a very weak bonding with the electrode.Under electrosurgical condition,arc discharge,which is unavoidable during the process of cutting and hemostasis,could generate high temperature,and then ablation and local microscopic melting occurred on the surface of 304 stainless steel electrode.Meanwhile,the tissue nano-particles produced by cell explosion hit the electrode surface under the acceleration of high-frequency electric field.The nano-particles bonded tightly with the ablation pits on the surface of electrode,mixed with the molten matrix metal,and diffused towards electrode matrix.As a result,an interfacial layer with non-uniformly mixed multi-phase ingredients was formed,causing a high binding strength of sticking tissue with electrode.2)Using 304 stainless steel active electrode as substrate,an anti-sticking active electrode with tungsten coating was prepared using magnetron sputtering.It was found that under electrosurgical condition,only slight arc-ablation occurred on the surface of tungsten-coated active electrode and no element diffusion happened at the interface of sticking tissue and electrode.Hence,the bonding strength of sticking tissue with the tungsten-coated active electrode was decreased by more than 90% in comparison with 304 stainless steel active electrode.3)Given that thermo-electric coupling effect underlies the function of minimally invasive electrosurgical devices,the effect of high-frequency electric field cannot be ignored in the studies of tissue sticking and anti-sticking strategies.