A new optical feedback interferometer for measuring red blood cell velocity distributions in individual capillaries: a feasibility study in microchannels

Egalement paru au 37ème Congrès de la Société de Biomécanique, à Toulouse, du 16 au 19 octobre 2012.International audienceThe dynamics of blood flow in microvascular networks is of great importance in the exchange of nutrient and waste substances between blood and living tissues. In these vessels of diameter less than 100µm, the development of quantitative methods for measuring the velocity of red blood cells (RBCs) is still challenging. In this context, the Dual-Slit (DS) technique, a temporal correlation technique, is commonly used. Our group has recently shown that, provided that several operational conditions are fulfilled, this technique can provide a precise measurement of the transverse velocity profile of RBCs. The measured velocities are maximal velocities in the depth of the channel . However, this technique requires expensive equipment (high speed camera) and the related data-treatment is time consuming. Moreover, the duration of the acquisition is long (typically 2 to 40s). For these reasons, on line measurements, especially in cases of transient regimes, are not possible. The aim of the present work is to determine whether Optical Feedback Interferometry, a new optical technique in the microfluidic domain which is based on the optical feedback effect in laser diodes, can be used to perform quantitative measurements of RBCs velocity in channels of size less than 100µm. Optical Feedback Interferometers (OFI) are indeed compact, low cost and simple sensors. They are known for providing much shorter response times than DS, currently lower than 10ms, while keeping the precision of traditional Laser Doppler Interferometers. This technique has been previously applied and validated to measure velocity profiles in 300µm diameter channels, but its feasibility in smaller channels is still to be demonstrated. For that purpose, the velocity profiles obtained by OFI and DS are compared, using PDMS microchannels and spheric monodisperse particle suspensions in set-up configurations where the DS has been previously validated