Evaluation of a Capacitively-Coupled, Non-Contact (through Clothing) Electrode or ECG Monitoring and Life Signs Detection for the Objective Force Warfighter

A new device that measures ECG inter-beat intervals through clothing is described and compared to a resistive contact electrode. The capacitively coupled non-contact electrode (CCNE) underwent a 40 person human trial at the Walter Reed Army Institute of Research this past year. This sensor can detect ECG and respiratory signals thru clothing and is being considered by the US Army as a physiological monitoring detection sensor on the Objective WarFighter uniform of the future. In this study, three CCNE sensors were compared to an FDA-approved monitor (3-lead) using contact electrodes to determine if the R-R inter-beat intervals of the two methods were "the same" or not. Results of the "at rest in supine position" for determining heart rate based on inter-beat intervals of the ECG are presented. The test results indicate that, relative to the ECG contact electrode, the CCNE sensors work for determining R-R inter-beat intervals reliably. Test subject variability in the different weight categories indicates similarity between the two types of electrodes and statistics for comparison are presented. The CCNE sensor gives "unbiased" estimates (116 out of 117 difference signals gave "unbiased" estimates). The CCNE sensor gave close estimates of the inter-beat intervals in 30 out of 39 test subjects with less than 14 ms differences. The CCNE difference signals give statistically "similar" results within each test subject (37 out of 39 test subjects had statistically similar results). Females showed more variability than males for each weight class. Males and females in weight class 5 had the largest measures of variability.