M-mode swept source optical coherence tomography for quantification of salt concentration in blood: An in vitro study

We report the use of M-mode swept source optical coherence tomography (SS-OCT) for measuring sodium chloride (NaCl) salt concentrations in liquid phantoms and in drawn whole blood based on temporal dynamics of light scattering. The Brownian motion of scattering particle is affected due to the change in viscosity of liquid. An autocorrelation function was determined from the power spectrum of SS-OCT signal and then was fit by mono and double exponential function to obtain decorrelation time. These translational decorrelation times corresponding to translational diffusion coefficients enabled us to find the controlled viscosity of the medium. The viscosities of the media were compared with literature values and a fair/excellent agreement was observed. Thus, the technique has ability to quantify the salt levels in terms of viscosity in nonflowing medium suspensions and many research routes necessary to determine its potential for in-vivo applications.