Beat to Beat Continuous Blood Pressure Estimation using Transmission Coefficient of On-body Antennas

Abstract

Background-Elevated blood pressure (BP) is a clear sign of hypertension, a condition associated with increased morbidity and mortality. Regular blood pressure monitoring is therefore crucial, but many cuff-based devices and their usage are restricted to monitoring while at rest. Method-This paper reports on the use of pair of microstrip patch antenna technology to obtain BP values through an innovative technique using the electromagnetic transmission coefficient waveforms. The change of transmission coefficient of EM waveforms emitted by the pair of antennas was analyzed and correlated with brachial artery thickness to radius ratios and hence, blood pressure assessment at different blood pressure points ranging from 60-140 mmHg. The latter is based on simulations and data algorithms performed at brachial artery diameters of 4.32, 4.33, 4.33, 4.56, 4.53 mm, to mimic the changing brachial artery diameter associated with a pulsatile blood flow. Result and Conclusion-In conclusion, the largest brachial artery thickness to radius of 0.9 is associated with a high blood pressure of 140-160 mmHg while normal blood pressure levels are referred to radius to thickness ratios of 0.5 and 0.6. Thus, the use of the transmission coefficient has shown a high accuracy for determining BP from the micro-patch antennas, which provides a novel option for continuous real-time, in the wild BP assessment and therefore more accurate information for the clinician.