Dielectrics for Non-Contact ECG Bioelectrodes: A Review

Sensing of bioelectrical potentials using a non-contact method remains promising for the long-term recording of heart biopotential signals. Recording electrocardiogram (ECG) in non-contact mode incorporates dielectric materials into capacitive bioelectrodes. Dielectrics have a strong influence on non-contact bioelectrodes because the coupling capacitance relies primarily on the dielectric properties of the material. This review seeks to present an evaluation of relevant literature concerning various dielectrics that have been documented. It examines the extent of existing constraints in biosensing performance, biocompatibility, bioelectrode ergonomics, skin contact impedance and biosignal processing, and how they affect capacitive ECG measurement. It is also discussed that the performance of bioelectrodes is determined by materials' dielectric properties, making the choice of materials an essential factor in non-contact ECG recording applications. Finally, suggestions to enable the development of non-contact bioelectrodes with improved performance were highlighted.