PMID- 35428772
OWN - NLM
STAT- MEDLINE
DCOM- 20220419
LR  - 20220601
IS  - 2045-2322 (Electronic)
IS  - 2045-2322 (Linking)
VI  - 12
IP  - 1
DP  - 2022 Apr 15
TI  - A new principle of pulse detection based on terahertz wave plethysmography.
PG  - 6347
LID - 10.1038/s41598-022-09801-w [doi]
LID - 6347
AB  - This study presents findings in the terahertz (THz) frequency spectrum for 
      non-contact cardiac sensing applications. Cardiac pulse information is 
      simultaneously extracted using THz waves based on the established principles in 
      electronics and optics. The first fundamental principle is micro-Doppler motion 
      effect. This motion based method, primarily using coherent phase information from 
      the radar receiver, has been widely exploited in microwave frequency bands and 
      has recently found popularity in millimeter waves (mmWave) for breathe rate and 
      heart rate detection. The second fundamental principle is reflectance based 
      optical measurement using infrared or visible light. The variation in the light 
      reflection is proportional to the volumetric change of the heart, often referred 
      as photoplethysmography (PPG). Herein, we introduce the concept of 
      terahertz-wave-plethysmography (TPG), which detects blood volume changes in the 
      upper dermis tissue layer by measuring the reflectance of THz waves, similar to 
      the existing remote PPG (rPPG) principle. The TPG principle is justified by 
      scientific deduction, electromagnetic wave simulations and carefully designed 
      experimental demonstrations. Additionally, pulse measurements from various 
      peripheral body parts of interest (BOI), palm, inner elbow, temple, fingertip and 
      forehead, are demonstrated using a wideband THz sensing system developed by the 
      Terahertz Electronics Lab at Arizona State University, Tempe. Among the BOIs 
      under test, it is found that the measurements from forehead BOI gives the best 
      accuracy with mean heart rate (HR) estimation error 1.51 beats per minute (BPM) 
      and standard deviation 1.08 BPM. The results validate the feasibility of TPG for 
      direct pulse monitoring. A comparative study on pulse sensitivity is conducted 
      between TPG and rPPG. The results indicate that the TPG contains more pulsatile 
      information from the forehead BOI than that in the rPPG signals in regular office 
      lighting condition and thus generate better heart rate estimation statistic in 
      the form of empirical cumulative distribution function of HR estimation error. 
      Last but not least, TPG penetrability test for covered skin is demonstrated using 
      two types of garment materials commonly used in daily life.
CI  - (c) 2022. The Author(s).
FAU - Rong, Yu
AU  - Rong Y
AD  - Center for Wireless Information Systems and Computational Architectures (WISCA) 
      at the School of Electrical, Computer and Energy Engineering, Arizona State 
      University, Tempe, AZ, 85281, USA. yrong5@asu.edu.
FAU - Theofanopoulos, Panagiotis C
AU  - Theofanopoulos PC
AD  - Terahertz Research Lab at the School of Electrical, Computer and Energy 
      Engineering, Arizona State University, Tempe, AZ, 85281, USA.
FAU - Trichopoulos, Georgios C
AU  - Trichopoulos GC
AD  - Terahertz Research Lab at the School of Electrical, Computer and Energy 
      Engineering, Arizona State University, Tempe, AZ, 85281, USA.
FAU - Bliss, Daniel W
AU  - Bliss DW
AD  - Center for Wireless Information Systems and Computational Architectures (WISCA) 
      at the School of Electrical, Computer and Energy Engineering, Arizona State 
      University, Tempe, AZ, 85281, USA.
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20220415
PL  - England
TA  - Sci Rep
JT  - Scientific reports
JID - 101563288
SB  - IM
MH  - Heart Rate
MH  - Humans
MH  - *Photoplethysmography
MH  - *Plethysmography
MH  - Pulse
MH  - Radar
PMC - PMC9012849
COIS- The authors declare no competing interests.
EDAT- 2022/04/17 06:00
MHDA- 2022/04/20 06:00
PMCR- 2022/04/15
CRDT- 2022/04/16 05:20
PHST- 2021/11/24 00:00 [received]
PHST- 2022/03/22 00:00 [accepted]
PHST- 2022/04/17 06:00 [pubmed]
PHST- 2022/04/20 06:00 [medline]
PHST- 2022/04/16 05:20 [entrez]
PHST- 2022/04/15 00:00 [pmc-release]
AID - 10.1038/s41598-022-09801-w [pii]
AID - 9801 [pii]
AID - 10.1038/s41598-022-09801-w [doi]
PST - epublish
SO  - Sci Rep. 2022 Apr 15;12(1):6347. doi: 10.1038/s41598-022-09801-w.