Doppler optical coherence tomography (DOCT) technique as well as ordinary OCT technique is based on interference of low coherent light. By using wide spectrum light sources it is possible to achieve spatial resolution of 1-5 µm which is over ten times better than a resolution of an ultrasound. Our home-made DOCT device is applied to measure flow velocity profiles of different suspensions from cellular protoplasm to industrial pigments and printable electronics inks. Flow velocity profile is important for determining rheological characteristics such as a viscosity and a shear rate of non-Newtonian suspensions. We also study the effect of the light scattering on the measured velocity profile of the suspension flow embedded into scattering medium. The results show that the specificity of the flow profile reconstruction in the case of the flow embedded into the scattering medium is the "non-zero" level of the detected frequencies at the rear border of the capillary.
The DOCT system is also used for imaging of cytoplasm shuttle flow in strands of Physarum Polycephalum. Slime mould Physarum is a unicellular organism representing a non-stationary system of cylindrical strands, which connect frontal zones of organism to the main body. Physarum shows the complex autowave amoeboid type of the cellular motility including contraction of the gel-like walls of the strands. These contractions generate gradients of pressure, which cause shuttle flow of the internal part of cytoplasm along the strands. The typical period of the oscillation of the strand with the diameter of about several hundred micrometers at the room temperature is about 1 min. For more details please visit OCT News web site.
A time-resolved Doppler OCT image of Physarum strand. Besides the velocity variations one can also see the contractions of the upper border of the strand wall.
Imaging of 1% Intralipid flow velocity profile by Doppler OCT.
J. Lauri, A.V. Bykov, A.V. Priezzhev, R. Myllylä, “Experimental study of the multiple scattering effect on the flow velocity profiles measured in Intralipid phantoms by DOCT”, Las. Phys. 21(4), 1-5 (2011). [PDF]
A.V. Bykov, A.V. Priezzhev, J. Lauri, R. Myllylä, "Doppler OCT imaging of cytoplasm shuttle flow in Physarum Polycephalum", J. Biophot. 2(8-9), 540-547 (2009). [PDF]
A.V. Bykov, A.V. Priezzhev, J. Lauri, R. Myllylä, "Visualisation of the oscillation dynamics of cytoplasm in a living cell of Physarum mixomycete plasmodium by the method of optical coherence Doppler tomography", Quantum Electron. 39(4), 382-384 (2009). [PDF]
Last updated: 9.9.2016