Patient Undergoing Bioelectrical Impedance Analysis (IMAGE) New York University Caption The Imp XCA, an FDA-approved device, uses a single frequency below 30 kHz to measure impedance and resistance of extracellular fluid. Credit NYU College of Nursing Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.