The Faraday Scalpel—Using Low-Level Electrochemical Currents for Tissue Lesioning and Ablation

Electrosurgery typically relies on high charge-density alternating currents, achieving tissue ablation via thermal dissipation or via irreversible electroporation mechanisms. These methods are relatively indiscriminate with respect to tissue type. We present the concept of using low-level direct currents to selectively ablate tissue via electrochemical reactions, as different cell types have different tolerances to various chemical species. We have assessed a range of possible cathodic and anodic processes. The main mechanism of interest, corresponding to the lowest current densities (10-100 μA/cm²), is the oxygen reduction reaction (ORR). ORR can be tuned to proceed via a 4-electron process, giving hypoxia, or it can be engineered to follow the 2-electron pathway and yield hydrogen peroxide. Both pathways can irreversibly damage certain cell types. We show in vitro and in vivo examples of using microelectrode systems to create on-demand hypoxic and/or oxidative stress conditions. Higher cathodic current densities can rapidly damage tissue with alkalization, applicable to tissues highly resistant to hypoxia/ROS. On the anodic side, we have identified the chloride oxidation reaction, with hypochlorite as a product, as a potent mechanism of tissue damage. Organic electronic materials have proven as excellent candidates for reliable ROS delivery. We discuss the application of faraday scalpel concepts in various in vivo models in the context of neurosurgery, and also examples of potential efficacy in cancer treatment.