A method for bio-electrical impedance analysis based on a step-voltage response

Bioimpedance analysis (BIA) has been researched broadly, since it is simple, it presents good results and the analysers are portable, allowing it to be used in field studies. This paper presents a new technique of BIA based on a step-voltage current response and bipolar electrode array. A prototype of this new kind of analyser was developed and constructed to test the technique. Bench tests were performed to calibrate the prototype and the obtained results were comparable to those of commercial analysers. Body composition tests were conducted on 67 subjects of both sexes. Besides the bioimpedance analysis, anthropometric measures, consisting of weight, height, circumference and skinfold thickness, were also obtained from the subjects to allow an estimation of the body composition from anthropometric equations established in the literature. The results point to a good correlation (Pearson coefficient, r = 0.9645) between the anthropometric estimated fat-free mass (FFM) and its analogue estimated by the new bioimpedance technique.