Simultaneous blood flow and oxygenation measurements
using an off-the-shelf spectrometer
Myeongsu Seong (成明洙)
1
, Phuong Minh Mai
2
, Kijoon Lee (李基準)
3
,
and Jae Gwan Kim (金載官)
1,2,
*
1
Department of Biomedical Science and Engineering, Institute of Integrated Technology,
Gwangju Institute of Science and Technology, Gwangju 61005, Korea
2
School of Electrical Engineering and Computer Science,
Gwangju Institute of Science and Technology, Gwangju 61005, Korea
3
School of Undergraduate Studies, Daegu Gyeongbuk Institute of Science and Technology, Daegu 42988, Korea
*Corresponding author: jaekim@gist.ac.kr
Received April 18, 2018; accepted May 21, 2018; posted online July 2, 2018
Blood oxygenation and flow are both important parameters in a living body. In this Letter, we introduce a simple
configuration to simultaneously measure blood flow and oxygenation using an off-the-shelf spectrometer. With
the integration time of 10 ms, flow phantom measurements, a liquid blood phantom test, and an arm cuff oc-
clusion paradigm were performed to validate the feasibility of the system. We expect this proof-of-concept study
would be widely adopted by other researchers for acquiring both blood flow and oxygenation changes due to its
straightforward configuration and the possibility of multimodal measurement.
OCIS codes: 170.2655, 170.3890, 170.7050, 170.6480.
doi: 10.3788/COL201816.071701.
Blood oxygenation and flow are both critical parameters
in a living body. Lack of oxygen supply will cause tissue
hypoxia, which, in turn, results in severe damage to the
tissue. If there is any problem in blood flow, the tissue will
suffer from lack of oxygen and nutrients because of prob-
lems in the material exchange between tissue and blood.
To monitor the blood flow and oxygenation changes si-
multaneously, various techniques have been introduced.
Among many techniques, optics-based techniques have
been extensively investigated due to their good temporal
resolution, non-invasiveness, and sensitivity to micro-
circulation, which is an indication of appropriate blood
supply to vital organs (e.g., brain).
To investigate deep tissue blood flow and oxygena-
tion, a dual-wavelength diffuse correlation spectroscopy
(DW-DCS) or DCS flow-oximeter was introduced, vali-
dated, and applied to various clinical and preclinical mon-
itoring applications
[1–3]
. Recently, we introduced and
validated dual-wavelength diffuse speckle contrast analysis
(DW-DSCA) as an alternative technique to DW-DCS
[4]
.
In this proof- of-concept study, we propose an off-the-
shelf spectrometer and two lasers based on simultaneous
blood flow and oxygenation measurement in deep tissue.
The system was validated with the flow and blood phan-
toms and preliminary in vivo measurement. Compared to
the previous research, the use of a spectrometer offers us
multiple advantages, including the inherent ability to be
expanded to a multimodal spectroscopy (e.g., monitoring
of blood flow, hemoglobin concentration, and fluores-
cence), no synchronization required
[4]
, no hardware
modification required
[5]
, and ease for positioning of the
fiber-optic probe on the region of interest
[4]
. Figure 1 shows
the schematic of the proposed system.
An off-the-shelf spectrometer (USB-4000, Ocean Optics)
wasusedinthisproof-of-concept study. A 400 μm core sized
optical fiber (#58–456, 0.22 N.A., Edmund Optics) was used
as a detection fiber. Integration time was set to 10 ms for the
spectrometer throughout the measurements. Two long co-
herence length lasers with 785 and 852 nm wavelengths
(CrystaLaser) were utilized as light sources. The lasers were
coupled with a 1 × 2 fiber combiner [1 × 2 planar lightwave
circuit (PLC) fiber combiner/splitter with 62.5 μm core size,
Fiberpia]. The one end of the combiner/splitter was con-
nected to an optical attenuator (BB-500-11-650/850-62.5/
125-M-35-3U3U-3-0.5-ND-SP , Oz Optics). By adjusting
the optical attenuator, optical powers for 785 and 852 nm
were set to 16.67 and 13.34 mW, respectively.
Fig. 1. Schematic of the proposed system. The system is config-
ured with two lasers, a 1 × 2 fiber combiner/splitter, a fiber
attenuator, and an off-the-shelf spectrometer coupled with detec-
tion fiber.
COL 16(7), 071701(2018) CHINESE OPTICS LETTERS July 10, 2018
1671-7694/2018/071701(5) 071701-1 © 2018 Chinese Optics Letters