Paperdoi:10.1364/boe.609878
Cross-polarised temple photoplethysmography for motion-robust and equitable cardiovascular sensing in virtual reality
Biomedical Optics Express, published 2026-10-21
(opens in a new tab)Alya Alshehhi et al., "Cross-polarised temple photoplethysmography for motion-robust and equitable cardiovascular sensing in virtual reality", doi:10.1364/boe.609878, CC BY 4.0
TL;DR
Near-infrared reflective PPG at the temple with orthogonal polarisers on the emitter and detector, which rejects specular/superficial reflections while keeping pulsatile light. 22 participants with free head movement in VR, simultaneous ECG and 3-axis accel as references; compared against unpolarised PPG.
- Form factor: head
Abstract
Virtual reality (VR) increasingly relies on continuous physiological signals, such as heart rate and heart-rate variability, to monitor users’ state in real time. The face is well suited to capturing these signals: the temple lies over a superficial artery, making it a strong photoplethysmography (PPG) site, but head motion and skin pigmentation can degrade optical cardiovascular measurements. We evaluated near-infrared cross-polarised temple PPG in 22 participants during free head movement in VR, using simultaneous ECG and three-axis acceleration as references. Orthogonal polarisers on the emitter and detector suppressed superficial reflections while preserving pulsatile light. Compared with unpolarised PPG, cross-polarisation was associated with a 29% reduction in the relative standard deviation of the DC baseline, a reduction in heart-rate bias from 1.84 to 0.01 bpm, and lower RMSSD and SDNN errors (43% and 44%). The largest HRV gains were observed in medium and darker skin groups. These results provide preliminary evidence that cross-polarisation may improve both the accuracy and the cross-skin-tone consistency of head-mounted PPG, thus supporting its use in next-generation smart eyewear and extended-reality devices.
Verbatim from the publisher's DOI record (opens in a new tab) · Publisher licence: https://creativecommons.org/licenses/by/4.0/
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Tasks & signals
Tasks
Signals
Keywords
How it works
- Wavelengths
- infrared
Cite this paper
Alshehhi, A., Moutaouakil, A. E., Abbasi, Q. H., & Ghannam, R. (2026). Cross-polarised temple photoplethysmography for motion-robust and equitable cardiovascular sensing in virtual reality. Biomedical Optics Express. https://doi.org/10.1364/boe.609878
Alshehhi, Alya, Amine El Moutaouakil, Qammer H. Abbasi, and Rami Ghannam. 2026. "Cross-polarised temple photoplethysmography for motion-robust and equitable cardiovascular sensing in virtual reality." Biomedical Optics Express. https://doi.org/10.1364/boe.609878.
Alshehhi, A., Moutaouakil, A. E., Abbasi, Q. H. and Ghannam, R. (2026) 'Cross-polarised temple photoplethysmography for motion-robust and equitable cardiovascular sensing in virtual reality', Biomedical Optics Express. doi: 10.1364/boe.609878.
Alshehhi, Alya, et al. "Cross-polarised temple photoplethysmography for motion-robust and equitable cardiovascular sensing in virtual reality." Biomedical Optics Express, 2026. https://doi.org/10.1364/boe.609878.
A. Alshehhi, A. E. Moutaouakil, Q. H. Abbasi, and R. Ghannam, "Cross-polarised temple photoplethysmography for motion-robust and equitable cardiovascular sensing in virtual reality," Biomedical Optics Express, 2026, doi: 10.1364/boe.609878.
@article{alshehhi2026crosspolarised,
title = {{Cross-polarised temple photoplethysmography for motion-robust and equitable cardiovascular sensing in virtual reality}},
author = {Alshehhi, Alya and Moutaouakil, Amine El and Abbasi, Qammer H. and Ghannam, Rami},
year = {2026},
journal = {Biomedical Optics Express},
doi = {10.1364/boe.609878}
}Added to the ChatPPG research hub
