Portable System for Time-Domain Diffuse Correlation Spectroscopy

We introduce a portable system for clinical studies based on time-domain diffuse correlation spectroscopy (DCS). After evaluating different lasers and detectors, the final system is based on a pulsed laser with about 550 ps pulsewidth, a coherence length of 38 mm, and two types of single-photon aval...

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Bibliographic Details
Published in:IEEE transactions on biomedical engineering 2019-11, Vol.66 (11), p.3014-3025
Main Authors: Tamborini, Davide, Stephens, Kimberly A., Wu, Melissa M., Farzam, Parya, Siegel, Andrew M., Shatrovoy, Oleg, Blackwell, Megan, Boas, David A., Carp, Stefan A., Franceschini, Maria Angela
Format: Article
Language:English
Subjects:
Adult
Avalanche diodes
Biomedical measurement
Blood flow
CMOS
Coherence length
Continuous radiation
Correlation
Correlation analysis
Detectors
Diffuse correlation spectroscopy
Dynamic Light Scattering - instrumentation
Dynamic Light Scattering - methods
Equipment Design
Forearm - blood supply
Forearm - diagnostic imaging
Forehead - blood supply
Forehead - diagnostic imaging
Humans
In vivo methods and tests
Lasers
Light effects
near infrared spectroscopy
Phantoms, Imaging
Photon avalanches
Photonics
Photons
Pulsed lasers
Reproducibility of Results
Signal Processing, Computer-Assisted - instrumentation
Signal to noise ratio
Skin
Spatial discrimination
Spatial resolution
Spectroscopy
Spectroscopy, Near-Infrared - instrumentation
Spectroscopy, Near-Infrared - methods
Spectrum analysis
Time domain analysis
time-domain diffuse correlation spectroscopy
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Description
Summary:We introduce a portable system for clinical studies based on time-domain diffuse correlation spectroscopy (DCS). After evaluating different lasers and detectors, the final system is based on a pulsed laser with about 550 ps pulsewidth, a coherence length of 38 mm, and two types of single-photon avalanche diodes (SPAD). The higher efficiency of the red-enhanced SPAD maximizes detection of the collected light, increasing the signal-to-noise ratio, while the better timing response of the CMOS SPAD optimizes the selection of late photons and increases spatial resolution. We discuss component selection and performance, and we present a full characterization of the system, measurement stability, a phantom-based validation study, and preliminary in vivo results collected from the forearms and the foreheads of four healthy subjects. With this system, we are able to resolve blood flow changes 1 cm below the skin surface with improved depth sensitivity and spatial resolution with respect to continuous wave DCS.
ISSN:0018-9294
1558-2531
1558-2531
DOI:10.1109/TBME.2019.2899762