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Continuous non-invasive blood pressure estimation based on impedance plethysmography measurements

Authors :

Fatemeh Shokri¹ Masoomeh Ashoorirad² Rasool Baghbani³

1- Hamedan University of Technology 2- Hamedan University of Technology 3- Hamedan Univesity of Technology

Keywords :

Continuous blood pressure،non-invasive monitoring،impedance plethysmography (IPG)،wearable device،mathematical modeling،two-stage calibration،COMSOL simulation

Abstract :

Continuous blood pressure (BP) monitoring is vital for cardiovascular care, yet existing cuffless methods often suffer from multi-sensor complexity and motion artifacts. This paper presents a novel, simplified approach for non-invasive, continuous BP estimation using a single-channel impedance plethysmography (IPG) system. A mathematically derived model correlates arterial impedance fluctuations directly with BP dynamics, enabled by a two-stage calibration process. To maximize signal fidelity, electrode configuration and injection current frequency (50 kHz) were rigorously optimized using a 3D forearm model in COMSOL Multiphysics, incorporating fluid-structure interaction (FSI) and electrical simulations. The proposed model was validated in MATLAB, demonstrating that an optimized electrode arrangement (29 mm stimulation, 12 mm sensing distance) achieved peak sensitivity (ΔZ = 41.47 mΩ). BP estimation results exhibited exceptional accuracy, with a mean absolute error (MAE) of 0.67 mmHg, a root mean square error (RMSE) of 1.39 mmHg, and a 0.998 correlation to the reference pressure. The system's performance surpasses the AAMI standard, confirming the viability of a single-sensor IPG approach as a low-cost, wearable alternative to complex multi-sensor methods for daily healthcare monitoring.