Multimodal Wrist Biosensor for Wearable Cuff-less Blood Pressure Monitoring System

Abstract

We propose a multimodal biosensor for use in continuous blood pressure (BP) monitoring system. Our proposed novel configuration measures photo-plethysmography (PPG) and impedance plethysmography (IPG) signals simultaneously from the subject wrist. The proposed biosensor system enables a fully non-intrusive system that is cuff-less, also utilize a single measurement site for maximum wearability and convenience of the patients. The efficacy of the proposed technique was evaluated on 10 young healthy subjects. Experimental results indicate that the pulse transit time (PTT)-based features calculated from an IPG peak and PPG maximum second derivative (f 14 ) had a relatively high correlation coefficient ( r ) to the reference BP, with −0.81 ± 0.08 and −0.78 ± 0.09 for systolic BP (SBP) and diastolic BP (DBP), respectively. Moreover, here we proposed two BP estimation models that utilize six- and one-point calibration models. The six-point model is based on the PTT, whereas the one-point model is based on the combined PTT and radial impedance (Z). Thus, in both models, we observed an adequate root-mean-square-error estimation performance, with 4.20 ± 1.66 and 2.90 ± 0.90 for SBP and DBP, respectively, with the PTT BP model; and 6.86 ± 1.65 and 6.67 ± 1.75 for SBP and DBP, respectively, with the PTT-Z BP model. This study suggests the possibility of estimating a subject’s BP from only wrist bio-signals. Thus, the six- and one-point PTT-Z calibration models offer adequate performance for practical applications.

Wearable Sensing and Telehealth Technology with Potential Applications in the Coronavirus Pandemic

“…Cuffless continuous monitoring approaches can be implemented into wearable and unobtrusive devices, such as watch [121], glasses [122,123], a wrist/armband [99,124,125], shirt [126], sleeping cushion [127], chair [128], smartphone [112], camera and flexible patch [114,129,130] as summarized in Fig. 8.…”

MEMS-Based Pulse Wave Sensor Utilizing a Piezoresistive Cantilever

“…Many methods have been proposed in previous studies to measure the pulse wave; these methods can be roughly divided into two categories based on their measurement principle, namely optics-based and force sensing-based methods. The most common device used in the optics-based method is the pulse oximeter, which is based on photoplethysmography [10,11]. A pulse oximeter detects pulse waves by monitoring the volume change of the blood vessel using an optical system consisting of an LED and a photodiode.…”

Pulse Transit Time-Pulse Wave Analysis Fusion Based on Wearable Wrist Ballistocardiogram for Cuff-Less Blood Pressure Trend Tracking

“…PTT is the time required for an arterial pulse wave to travel between two different sites in the arterial tree, e.g., between a central artery (e.g., ascending aorta or carotid artery) and a peripheral artery (e.g., radial artery, digital artery, or tibial artery). Vast majority of prior work has investigated the use of pulse arrival time (PAT: the time interval between the R wave in the electrocardiogram (ECG) and a fiducial point in the photoplethysmogram (PPG); see 2 and the references therein), while other work has explored the use of PTT derived using other physiological signals, such as impedance plethysmography (IPG)-PPG pair 3 , PPG pair (see 4 and the references therein), ballistocardiogram (BCG)-PPG pair [5][6][7] , and seismocardiogram (SCG)-PPG pair 8 to list a few. Second, PWA approach exploits fiducial points in an arterial pulse wave to construct predictors of BP, often in conjunction with the state-of-the-art data mining and machine learning techniques.…”

“…In addition, noting that PTT computed using diastolic fiducial points may strictly correspond to only diastolic BP (DP) whereas PAT (which includes the pre-ejection period (PEP)) may better correspond to systolic BP (SP) than DP 2 , PTT-PWA has the potential to enable independent tracking of DP and SP 15 . Prior work has reported the fusion of IPG-PPG PTT and IPG PWA 16 , IPG PTT and IPG PWA 3,17 , PAT and PPG PWA [18][19][20][21] , BCG-PPG PTT and BCG PWA 5 , BCG PTT-PWA…”