I worked on this project from March 2003 to the end of April 2007. Particle Image Velocimetry (PIV) was extended for use in in vivo measurements in blood vessels with a diameter of order 100 μm.
The development, the regulation, and the pathology of the circulatory system (e.g. cardiogenesis, thermoregulation, atherosclerosis) are determined by blood flow induced mechanical forces. While this proposition has been confirmed during recent years, the exact mechanisms still remain unclear. This is mainly due to the fact that those forces could hardly be measured. The goal of the research described in this thesis is the development of a measurement technique that can provide such data for living organisms.
Fluid mechanical forces can be deduced from spatial velocity information, as provided by particle image velocimetry. Small, artificial, fluorescent particles with a hydrophilic coating are used to determine the fluid velocity. Fluorescence enables the interference-free recording of the particle motion, and the coating makes the particles "invisible" to the biological system. Three dimensional flow is accessed by a combined measurement of multiple planes and a numerical reconstruction method.
The three dimensional flow distribution in a beating embryonic chicken heart with an inner diameter of 200 μm could accurately be determined. The measurements explain high gene expression levels found at the inner curvature of bends.
Please refer to dr.ir Poelma for ongoing research in this field.