Contactless and cuffless monitoring of blood pressure on a chair using e-textile materials

Blood pressure (BP) can be measured cufflessly and noninvasively by using pulse transit time, which is obtained from simultaneously recorded electrocardiogram (ECG) and photoplethysmogram (PPG). To apply this BP monitoring technique in daily life, an office chair was modified into a contactless and cuffless BP-monitoring device using e-textile materials. In this study, twelve normotensive subjects, including 6 males and 6 females, were recruited for testing this BP-monitoring chair. During the experiment, exercise was carried out to obtain a wider range of BP. In total, 62 pairs of systolic BP (SBP) and diastolic BP (DBP) estimations were made. Readings from a clinically approved cuff-based automatic BP monitor was used as reference. The results showed that the estimated SBP and DBP differed from their references by -6.3 +/- 10.5 mmHg and -0.7 +/- 4.9 mmHg respectively. It was found that the SBP estimation errors mainly came from the data obtained immediately after exercise. Further improvement should be made to minimize those errors. However, this concept is potentially useful in self BP monitoring for home healthcare.