Evaluation of ImpediMed SFB7 BIS device for low-impedance measurements

The SFB7 bioimpedance spectroscopy (BIS) device from ImpediMed is a widely utilized tool for clinical research in a variety of applications, marketed for the estimation of body composition in individuals. This device has a rated accuracy of 1% for measurements from 50 Ω to 1 kΩ from 3 kHz to 1 MHz, making it an ideal choice for the measurement of full-body impedance. Recent research has also used this device to collect impedance measurements from localized regions of tissue which in some cases may be below the 50 Ω rated value. In this work, the measurements of impedances below 50 Ω are compared to measurements collected from a Keysight E4990A impedance analyzer in this low impedance range. Concluding that the SFB7 device is 1% accurate for resistance measurements as low as 10 Ω for frequencies below 100 kHz and 5% accurate for frequencies to 1 MHz. While 1 Ω measurements are possible, their much higher variability decrease their expected accuracy to approximately 5% for frequencies below 100 kHz and 30% for frequencies up to 1 MHz.