Document Type

Article

Publication Date

2026

DOI

10.1088/2977-8425/ae87a3

Publication Title

Medical Sensors & Imaging

Pages

31 pp.

Abstract

Objective: Heart rate variability (HRV), quantified via the instantaneous frequency (IF) of arterial pulse signals, is a key indicator of cardiovascular (CV) regulation. This study presents a theoretical and experimental investigation of how motion artifacts (MA) influence IF-and thus HRVmeasured with a tactile sensor, emphasizing underlying mechanisms rather than population-level validation. Approach: Building on a previously developed single-degree-of-freedom (SDOF) model of the tissue-contact-sensor (TCS) stack between the sensor and the artery, MA is represented as low-frequency baseline drift and time-varying system parameters (TVSP) of the TCS stack. Analytical expressions quantify the effect of MA on the IF of each harmonic of the measured pulse signal. Experimental measurements from two healthy subjects at the radial artery (RA) and carotid artery (CA), under at-rest and post-exercise conditions, illustrate the theoretical predictions. Traditional beat-to-beat HRV, derived from pulse intervals, is compared to IF-based HRV to highlight methodological differences. Main Results: Measured HRV deviates from underlying physiological variability through two mechanisms: (1) measurement system dynamics that scale with temporal heart rate (HR) variations, and (2) MA-induced perturbations associated with TVSP. The first mechanism preferentially amplifies rapid HR fluctuations while minimally affecting low-HRV conditions, even without MA. MA introduces additional variability, more pronounced at the CA than at the RA. IF-based HRV explicitly reveals measurement effects that are masked in traditional beatto-beat HRV. Significance: This study provides a mechanistic framework for understanding how measurement system dynamics and MA influence HRV estimation and related metrics, including respiration, pulse transit time (PTT), and carotid-radial pulse wave velocity (PWV). It also explains why IF-based and traditional beat-to-beat HRV can lead to different interpretations. These findings show that pulse-derived HRV reflects both physiological variability and measurement-induced effects, emphasizing the need for model-based interpretation in clinical applications.

Rights

© 2026 The Authors.

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Original Publication Citation

Hasan, M., & Hao, Z. (2026). Influence of motion artifacts on instantaneous frequency based heart rate variability of arterial pulse signals measured by a tactile sensor: An analytical study. Medical Sensors & Imaging. Advance online publication. https://doi.org/10.1088/2977-8425/ae87a3

ORCID

0009-0006-7544-5938 (Hasan), 0000-0003-2024-1947 (Hao)

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