A 145.2dB-DR Baseline-Tracking Impedance Plethysmogram IC for Neckband-Based Blood Pressure and Cardiovascular Monitoring
Chan Park, Hyunjoong Kim, Kwangmuk Lee, Dae Sik Keum, Dong Pyo Jang, Jae Joon Kim
Abstract
Recent wearable blood pressure (BP) measurements that are based on the pulse transit time (PTT) require additional bothersome contact for their subordinate electrocardiogram (ECG), such as from the opposite hand's finger. This extra contact disrupts continuous BP monitoring during daily activities. A proposed neckband-based device allows continuous BP measurement just by wearing it, and a proposed baseline-tracking impedance plethysmogram (IPG) facilitates daily-life BP measurement based on the PTT at the carotid artery [1]. For this purpose, a mixed-mode baseline cancellation (MM-BC) scheme is proposed to achieve wide-range fine-canceling capability for baseline wanders; this improves upon conventional bio-impedance methods that adopt only one analog-tuned [2] or digital-assisted [3] control loop. For fine and robust detection of the IPG, a two-step CT ADC is designed to include an artifact detection scheme. For effective support of 4-electrode (4E) and 2-electrode (2E) setups in bio-impedance measurements, a proposed phase-synchronization scheme requires only one channel for the I/Q detection, while conventional schemes utilize two channels [2]–[5]. For system-level verification, a bio-potential channel for the ECG is also integrated, and the IPG-based BP function is experimentally verified through a neckband device prototype.