Confounding Factors and Their Mitigation in Measurements of Bioelectrical Impedance at the Skin Interface

Background: Bioelectrical impedance measurement is a technique used in engineering (development of different wearable biosensors with diverse applications), in the medical field (health monitoring and diagnosis), and in biomedical research (fundamental and applied). Problem: despite its long history and existence of standardized techniques, measurement results can often be unreliable and plagued by high variance (intra- and inter-subject measurement), which can distort the correct interpretation of the results. Methods: we have reviewed bioelectrical impedance measurements from both engineering and medical research teams over the past 60 years, with a focus on factors that might influence the skin–electrode interface. Results: We identified 40 confounding factors in 10 different categories, some of which are sometimes overlooked in applied research, and we propose mitigation strategies for each one.