The effect of cathodic voltage-controlled electrical stimulation of titanium on the surrounding microenvironment pH: An experimental and computational study

Cathodic voltage-controlled electrical stimulation (CVCES) is being explored for the treatment and pre-vention of orthopedic implant associated infections. However, the precise mechanism of the antimicrobial action of CVCES is not fully understood. Here, we present a combined experimental and computational study evaluating the spatial and temporal evolution of pH in a saline electrolyte near a titanium electrode in response to CVCES magnitudes of-1.0 V,-1.5 V, and-1.8 V vs Ag/AgCl. Scanning electrochemical mi-croscopy was used to make spatially resolved measurements of pH with potentiometric microelectrodes. COMSOL Multiphysics was utilized to construct a computational model to predict the effects of the CVCES on the surrounding microenvironment. The outcomes showed that an alkalization of the microenviron-ment occurs that is voltage-dependent, with application of greater cathodic potentials resulting in greater alkaline pH shifts. The pH displayed a rapid, logarithmic-like increase over time at a distance of 10 mu from the polarized titanium surface. The pH increase was more sluggish at a distance of 5 mm from the tita-nium surface, due to the longer diffusion length for the reduction reaction products that are responsible for the alkalization. The computational methods developed herein show sufficiently good agreement with the experimental results to warrant further development as a tool to help guide the development of an-timicrobial electrochemical treatment methodologies. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

This study evaluated the effects of cathodic voltage-controlled electrical stimulation (CVCES) on the pH near a titanium electrode using a combination of experimental measurements and computational modeling. The results showed that a greater cathodic potential led to a more significant alkalization effect on the microenvironment, with pH increasing rapidly at a distance of 10 micrometers from the polarized surface. The computational model developed demonstrated good agreement with the experimental data and shows promise as a tool for guiding the development of antimicrobial electrochemical treatment methods.