Characterization of the Analog Device Inc (ADI) MAX30009 Bioimpedance Analog Front End Chip

An increasing number of novel wearable health monitors utilize Bioimpedance (BioZ) to deliver meaningful health insights. Several integrated circuit BioZ chips have emerged to measure BioZ within the space constraints of wearable applications. One new integrated circuit BioZ chip, the MAX30009 Bioimpedance Analog Front End (AFE), has never been characterized. This paper aims to provide an initial characterization of the MAX30009. The AFE's performance was evaluated through a series of tests exploring the chip's accuracy, precision, and performance in the presence of realistic RC contact impedance circuits. The experiments found the AFE can achieve a standard deviation of 0.067 ohms and 0.033 degrees for a 100-ohm resistor and 0.0575 ohms and 0.249 degrees for a 227 nF capacitor at 50 kHz. Ultimately, a Bland-Altman analysis suggests that over the frequency range of 1 kHz - 340 kHz, the MAX30009 is interchangeable with a reference Zurich Instruments Impedance Analyzer. Clinical Relevance-The MAX30009 Bioimpedance chip is demonstrated to be interchangeable with a Zurich Instruments impedance analyzer over the range of 1 kHz - 340 kHz.