{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,1]],"date-time":"2026-02-01T05:07:39Z","timestamp":1769922459330,"version":"3.49.0"},"reference-count":44,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2022,1,25]],"date-time":"2022-01-25T00:00:00Z","timestamp":1643068800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Non-invasive measurement of the arterial blood speed gives important health information such as cardio output and blood supplies to vital organs. The magnitude and change in arterial blood speed are key indicators of the health conditions and development and progression of diseases. We demonstrated a simple technique to directly measure the blood flow speed in main arteries based on the diffused light model. The concept is demonstrated with a phantom that uses intralipid hydrogel to model the biological tissue and an embedded glass tube with flowing human blood to model the blood vessel. The correlation function of the measured photocurrent was used to find the electrical field correlation function via the Siegert relation. We have shown that the characteristic decorrelation rate (i.e., the inverse of the decoherent time) is linearly proportional to the blood speed and independent of the tube diameter. This striking property can be explained by an approximate analytic solution for the diffused light equation in the regime where the convective flow is the dominating factor for decorrelation. As a result, we have demonstrated a non-invasive method of measuring arterial blood speed without any prior knowledge or assumption about the geometric or mechanic properties of the blood vessels.<\/jats:p>","DOI":"10.3390\/s22030897","type":"journal-article","created":{"date-parts":[[2022,1,25]],"date-time":"2022-01-25T21:07:11Z","timestamp":1643144831000},"page":"897","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["Non-Invasive Blood Flow Speed Measurement Using Optics"],"prefix":"10.3390","volume":"22","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-3218-8322","authenticated-orcid":false,"given":"Alex Ce","family":"Zhang","sequence":"first","affiliation":[{"name":"Department of Electrical and Computer Engineering, University of California San Diego, La Jolla, CA 92093-0407, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yu-Hwa","family":"Lo","sequence":"additional","affiliation":[{"name":"Department of Electrical and Computer Engineering, University of California San Diego, La Jolla, CA 92093-0407, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2022,1,25]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1601","DOI":"10.1093\/clinchem\/38.9.1601","article-title":"Pulse oximetry: Theory and applications for noninvasive monitoring","volume":"38","author":"Mendelson","year":"1992","journal-title":"Clin. Chem."},{"key":"ref_2","first-page":"203","article-title":"Measuring blood flow: Techniques and applications\u2014A review","volume":"6","author":"Jayanthy","year":"2011","journal-title":"Int. J. Res. Rev. Appl. Sci."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Poelma, C., Kloosterman, A., Hierck, B.P., and Westerweel, J. (2012). Accurate blood flow measurements: Are artificial tracers necessary?. PLoS ONE, 7.","DOI":"10.1371\/journal.pone.0045247"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1172\/JCI100106","article-title":"Studies on the velocity of blood flow: I. The method utilized","volume":"4","author":"Blumgart","year":"1927","journal-title":"J. Clin. Investig."},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Heldt, T. (2018). A wearable transcranial Doppler ultrasound phased array system. Intracranial Pressure & Neuromonitoring XVI, Springer.","DOI":"10.1007\/978-3-319-65798-1"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"4097","DOI":"10.1143\/JJAP.31.4097","article-title":"Model for measurement of tissue oxygenated blood volume by the dynamic light scattering method","volume":"31","author":"Kashima","year":"1992","journal-title":"Jpn. J. Appl. Phys."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"2177","DOI":"10.1143\/JJAP.32.2177","article-title":"Study of measuring the velocity of erythrocytes in tissue by the dynamic light scattering method","volume":"32","author":"Kashima","year":"1993","journal-title":"Jpn. J. Appl. Phys."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"2097","DOI":"10.1364\/AO.20.002097","article-title":"Model for laser Doppler measurements of blood flow in tissue","volume":"20","author":"Bonner","year":"1981","journal-title":"Appl. Opt."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"269","DOI":"10.1007\/s10103-007-0524-0","article-title":"Review of methodological developments in laser Doppler flowmetry","volume":"24","author":"Rajan","year":"2009","journal-title":"Lasers Med. Sci."},{"key":"ref_10","unstructured":"Ishimaru, A. (1978). Wave Propagation and Scattering in Random Media, Academic press."},{"key":"ref_11","unstructured":"Wang, L.V., and Wu, H.I. (2012). Biomedical Optics: Principles and Imaging, John Wiley & Sons."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"076701","DOI":"10.1088\/0034-4885\/73\/7\/076701","article-title":"Diffuse optics for tissue monitoring and tomography","volume":"73","author":"Durduran","year":"2010","journal-title":"Rep. Prog. Phys."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Vishwanath, K., and Zanfardino, S. (2019). Diffuse Correlation Spectroscopy at Short Source-Detector Separations: Simulations, Experiments and Theoretical Modeling. Appl. Sci., 9.","DOI":"10.3390\/app9153047"},{"key":"ref_14","first-page":"105732K","article-title":"Sensitivity of diffuse correlation spectroscopy to flow rates: A study with tissue simulating optical phantoms","volume":"Volume 10573","author":"Zanfardino","year":"2018","journal-title":"Medical Imaging 2018: Physics of Medical Imaging"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"031412","DOI":"10.1117\/1.NPh.3.3.031412","article-title":"Establishing the diffuse correlation spectroscopy signal relationship with blood flow","volume":"3","author":"Boas","year":"2016","journal-title":"Neurophotonics"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"51","DOI":"10.1016\/j.neuroimage.2013.06.017","article-title":"Diffuse correlation spectroscopy for non-invasive, micro-vascular cerebral blood flow measurement","volume":"85","author":"Durduran","year":"2014","journal-title":"Neuroimage"},{"key":"ref_17","first-page":"223","article-title":"Neurophotonics: Non-invasive optical techniques for monitoring brain functions","volume":"29","author":"Torricelli","year":"2014","journal-title":"Funct. Neurol."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"4288","DOI":"10.1364\/BOE.6.004288","article-title":"Assessment of the best flow model to characterize diffuse correlation spectroscopy data acquired directly on the brain","volume":"6","author":"Verdecchia","year":"2015","journal-title":"Biomed. Opt. Express"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"2860","DOI":"10.1364\/AO.32.002860","article-title":"Dynamic light scattering with single-mode and multimode receivers","volume":"32","year":"1993","journal-title":"Appl. Opt."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"035002","DOI":"10.1117\/1.JBO.19.3.035002","article-title":"Dependence of optical scattering from Intralipid in gelatin-gel based tissue-mimicking phantoms on mixing temperature and time","volume":"19","author":"Lai","year":"2014","journal-title":"J. Biomed. Opt."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"041102","DOI":"10.1117\/1.2335429","article-title":"Review of tissue simulating phantoms for optical spectroscopy, imaging and dosimetry","volume":"11","author":"Pogue","year":"2006","journal-title":"J. Biomed. Opt."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"510","DOI":"10.1002\/lsm.1900120510","article-title":"Optical properties of Intralipid: A phantom medium for light propagation studies","volume":"12","author":"Flock","year":"1992","journal-title":"Lasers Surg. Med."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1151","DOI":"10.1364\/JOSAA.22.001151","article-title":"Determination of refractive indices of porcine skin tissues and intralipid at eight wavelengths between 325 and 1557 nm","volume":"22","author":"Ding","year":"2005","journal-title":"JOSA A"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"133","DOI":"10.1016\/S0079-6638(08)70188-4","article-title":"III Light beating spectroscopy","volume":"Volume 8","author":"Cummins","year":"1970","journal-title":"Progress in Optics"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"037001","DOI":"10.1117\/1.JBO.18.3.037001","article-title":"Using optical fibers with different modes to improve the signal-to-noise ratio of diffuse correlation spectroscopy flow-oximeter measurements","volume":"18","author":"He","year":"2013","journal-title":"J. Biomed. Opt."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"2727","DOI":"10.1364\/JOSAA.11.002727","article-title":"Boundary conditions for the diffusion equation in radiative transfer","volume":"11","author":"Haskell","year":"1994","journal-title":"JOSA A"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"192","DOI":"10.1364\/JOSAA.14.000192","article-title":"Spatially varying dynamical properties of turbid media probed with diffusing temporal light correlation","volume":"14","author":"Boas","year":"1997","journal-title":"JOSA A"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"3493","DOI":"10.1364\/BOE.8.003493","article-title":"Pulse wave analysis with diffusing-wave spectroscopy","volume":"8","author":"Belau","year":"2017","journal-title":"Biomed. Opt. Express"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"15","DOI":"10.1364\/JOSAB.7.000015","article-title":"Diffusing-wave spectroscopy in a shear flow","volume":"7","author":"Wu","year":"1990","journal-title":"JOSA B"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"129","DOI":"10.1177\/8756479307302338","article-title":"Arterial vascular hemodynamics","volume":"23","author":"Owen","year":"2007","journal-title":"J. Diagn. Med. Sonogr."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"383","DOI":"10.1016\/0021-9797(79)90248-0","article-title":"Flow behavior of erythrocytes. II. Particle motions in concentrated suspensions of ghost cells","volume":"71","author":"Goldsmith","year":"1979","journal-title":"J. Colloid Interface Sci."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"2752","DOI":"10.1002\/mrm.26919","article-title":"Characterization of the diffusion coefficient of blood","volume":"79","author":"Funck","year":"2018","journal-title":"Magn. Reson. Med."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"151","DOI":"10.1097\/MAT.0b013e3181d4ed0f","article-title":"Shear rate and hematocrit effects on the apparent diffusivity of urea in suspensions of bovine erythrocytes","volume":"56","author":"Nanne","year":"2010","journal-title":"ASAIO J."},{"key":"ref_34","doi-asserted-by":"crossref","unstructured":"Higgins, J.M., Eddington, D.T., Bhatia, S.N., and Mahadevan, L. (2009). Statistical dynamics of flowing red blood cells by morphological image processing. PLoS Comput. Biol., 5.","DOI":"10.1371\/journal.pcbi.1000288"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"20140403","DOI":"10.1098\/rsif.2014.0403","article-title":"Synergy between shear-induced migration and secondary flows on red blood cells transport in arteries: Considerations on oxygen transport","volume":"11","author":"Biasetti","year":"2014","journal-title":"J. R. Soc. Interface"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"479","DOI":"10.1007\/BF02698294","article-title":"Evaluation of shear-induced particle diffusivity in red cell ghosts suspensions","volume":"18","author":"Cha","year":"2001","journal-title":"Korean J. Chem. Eng."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"e201700070","DOI":"10.1002\/jbio.201700070","article-title":"Shear-induced diffusion of red blood cells measured with dynamic light scattering-optical coherence tomography","volume":"11","author":"Tang","year":"2018","journal-title":"J. Biophotonics"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"027006","DOI":"10.1117\/1.JBO.22.2.027006","article-title":"Theoretical model of blood flow measurement by diffuse correlation spectroscopy","volume":"22","author":"Boas","year":"2017","journal-title":"J. Biomed. Opt."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"1888","DOI":"10.1364\/JOSAA.32.001888","article-title":"Detection and estimation of liquid flow through a pipe in a tissue-like object with ultrasound-assisted diffuse correlation spectroscopy","volume":"32","author":"Chandran","year":"2015","journal-title":"JOSA A"},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"603","DOI":"10.1161\/01.CIR.40.5.603","article-title":"Measurement of instantaneous blood flow velocity and pressure in conscious man with a catheter-tip velocity probe","volume":"40","author":"Gabe","year":"1969","journal-title":"Circulation"},{"key":"ref_41","doi-asserted-by":"crossref","unstructured":"Lazareva, E.N., and Tuchin, V.V. (2018). Blood refractive index modelling in the visible and near infrared spectral regions. J. Biomed. Photonics Eng., 4.","DOI":"10.18287\/JBPE18.04.010503"},{"key":"ref_42","first-page":"517","article-title":"Refractive index of human whole blood with different types in the visible and near-infrared ranges","volume":"Volume 3914","author":"Li","year":"2000","journal-title":"Laser-Tissue Interaction XI: Photochemical, Photothermal, and Photomechanical"},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"453","DOI":"10.1007\/s10103-013-1446-7","article-title":"A literature review and novel theoretical approach on the optical properties of whole blood","volume":"29","author":"Bosschaart","year":"2014","journal-title":"Lasers Med. Sci."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"R37","DOI":"10.1088\/0031-9155\/58\/11\/R37","article-title":"Optical properties of biological tissues: A review","volume":"58","author":"Jacques","year":"2013","journal-title":"Phys. Med. Biol."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/22\/3\/897\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T22:07:00Z","timestamp":1760134020000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/22\/3\/897"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,1,25]]},"references-count":44,"journal-issue":{"issue":"3","published-online":{"date-parts":[[2022,2]]}},"alternative-id":["s22030897"],"URL":"https:\/\/doi.org\/10.3390\/s22030897","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2022,1,25]]}}}