Abstract: Early detection and continuous monitoring of cardiovascular health are essential to prevent decline and support preventive care. Traditionally, ECG is used for monitoring, but it requires electrodes and a clinical setting. For regular, continuous monitoring, we need a technique that is easy to use and convenient for users. Ballistocardiography (BCG) captures the whole-body recoil generated by cardiac ejection, providing a contactless alternative.

This seminar presents the design and evaluation of a BCG chair as a posture-aware platform for unobtrusive cardiovascular monitoring. Foil strain gauges on the four chair legs, configured as a full Wheatstone bridge, transduce cardiac reaction forces into a BCG waveform, with a three-lead ECG and a pulse oximeter as references. From the recoil signal, heart rate (HR), heart rate variability (HRV), and respiratory rate (RR) were extracted. HRV was estimated across time, frequency, and nonlinear domains using wavelet-based J-peak detection, showing narrow limits of agreement with the ECG (r > 0.97 across all metrics; interbeat interval R² = 0.99). HR, HRV, and RR were then estimated under varying breathing conditions, with RR recovered via spectral analysis of the respiratory envelope, again showing narrow limits of agreement with reference (mean absolute error: HR 0.09 bpm, RR 0.50 breaths/min, RMSSD 3.84 ms).

The work then examines the influence of posture on the BCG. Sitting posture and spinal curvature produced reproducible changes in the systolic-phase timing of the waveform while heart rate remained unaffected (p < 0.05), indicating a mechanical rather than autonomic effect. A feature-level analysis across sitting and standing cohorts showed that posture redistributes the waveform rather than uniformly scaling it.

This work shows that smart furniture with embedded sensors can estimate vital signs such as HR, RR, and HRV and maintain continuous records at home, supporting preventive care. With more advanced cardiac parameter estimation in the future, posture can be accounted for so that measurement errors are not mistaken for a real decline in health when they are actually caused by a change in posture. The seminar concludes by outlining the measurement challenges observed and directions for future work, including validation in larger, more diverse cohorts and clinical pilots in at-risk populations.

Event Details
Title: Posture-Aware Chair-Based Ballistocardiography for Unobtrusive Cardiovascular Monitoring
Date: August 11, 2026 at 3:00 PM
Venue: ESB244 / Google Meet (https://meet.google.com/usq-oawy-uwu)
Speaker: Ms. Gunjan singh (EE22D020)
Guide: Dr. Mohanasankar Sivaprakasam
Type: PHD seminar

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