title: Feasibility of long-distance heart rate monitoring using transmittance photoplethysmographic imaging (PPGI).
abstract: Photoplethysmography (PPG) devices are widely used for monitoring cardiovascular function. However, these devices require skin contact, which restricts their use to at-rest short-term monitoring. Photoplethysmographic imaging (PPGI) has been recently proposed as a non-contact monitoring alternative by measuring blood pulse signals across a spatial region of interest. Existing systems operate in reflectance mode, many of which are limited to short-distance monitoring and are prone to temporal changes in ambient illumination. This paper is the first study to investigate the feasibility of long-distance non-contact cardiovascular monitoring at the supermeter level using transmittance PPGI. For this purpose, a novel PPGI system was designed at the hardware and software level. Temporally coded illumination (TCI) is proposed for ambient correction, and a signal processing pipeline is proposed for PPGI signal extraction. Experimental results show that the processing steps yielded a substantially more pulsatile PPGI signal than the raw acquired signal, resulting in statistically significant increases in correlation to ground-truth PPG in both short- and long-distance monitoring. The results support the hypothesis that long-distance heart rate monitoring is feasible using transmittance PPGI, allowing for new possibilities of monitoring cardiovascular function in a non-contact manner.
authors.affiliation: University of Waterloo, Department of Systems Design Engineering, Waterloo, N2L3G1, Canada.
authors.forename: Robert
authors.initials: R
authors.lastname: Amelard
authors.affiliation: University of Waterloo, Department of Systems Design Engineering, Waterloo, N2L3G1, Canada.
authors.forename: Christian
authors.initials: C
authors.lastname: Scharfenberger
authors.affiliation: University of Waterloo, Department of Systems Design Engineering, Waterloo, N2L3G1, Canada.
authors.forename: Farnoud
authors.initials: F
authors.lastname: Kazemzadeh
authors.affiliation: University of Waterloo, Department of Kinesiology, Waterloo, N2L3G1, Canada.
authors.forename: Kaylen J
authors.initials: KJ
authors.lastname: Pfisterer
authors.affiliation: University of Waterloo, Department of Mechanical and Mechatronics Engineering, Waterloo, N2L3G1, Canada.
authors.forename: Bill S
authors.initials: BS
authors.lastname: Lin
authors.affiliation: University of Waterloo, Department of Systems Design Engineering, Waterloo, N2L3G1, Canada.
authors.forename: David A
authors.initials: DA
authors.lastname: Clausi
authors.affiliation: University of Waterloo, Department of Systems Design Engineering, Waterloo, N2L3G1, Canada.
authors.forename: Alexander
authors.initials: A
authors.lastname: Wong
mesh_terms: D000328:Adult; D003952:Diagnostic Imaging; D005240:Feasibility Studies; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008029:Lighting; D008297:Male; D008991:Monitoring, Physiologic; D017156:Photoplethysmography / Q000379:methods*; D012815:Signal Processing, Computer-Assisted