Investigation of ECG electrodes for burn wounds

Abstract: This project aims to investigate a variety of electrodes for ECG (electrocardiogram) measurements and find suitable ones for burn wounded skin in association with the Burn center in Uppsala University Hospital.   To this purpose, the electrical properties (in particular, electrical impedance and equivalent circuit) of electrodes and the influence of the skin on the electrical properties are looked into, and various common artefacts in ECG measurements are investigated, such as wandering baseline (caused by perspiration, respiration, patient movement and poor electrode contact), muscle tremor artefact, 50-60 Hz power line interference and measurement noise.   Simulation of a burn wound was done by putting Ringer’s acetate between two electrodes gel to gel. Six different electrodes made with either a solid or wet gel for the electrolyte were tested, three of which (Ambu Bluesensor L-00-S/25, Ambu Bluesensor R-00-S/25, Milmedtek T-VO01) have wet gel, and three of which (3M 2670-5, Medtronic Arbo, and Ambu Whitesensor WSP30-00-S/50) have solid gel.   The tests showed that the impedance of the electrodes changed as expected and was in almost all cases lowered. An increase in phase shift was also observed with burn wound simulation but could not be proven to relate with increased polarization.   The results showed its wet gel and adhesive developed for sweaty/wet skin, Ambu Bluesensor R-00-S/25 is recommended.   Suggestions for further investigation would be to see if the interference could be solved by impedance balancing the electrodes or to investigate if there is a greater coupling between the wet burn wounds and the main 230V 50Hz network causing higher currents and voltage drops in the body increasing the risk of common mode to differential mode conversion.