Measurement of microfluidic flow velocity profile with two Doppler optical coherence tomography systems

摘要

Doppler Optical Coherence Tomography (DOCT) is a useful technique for flow measurements. Its potential applications include industrial suspension viscosity measurements and blood flow measurements. In this work, a flow velocity profile of 1 % Intralipid was measured in a capillary with an inner diameter of 0.8 mm and in a microfluidic channel with a cross-section of 1000 μm × 100 μm. Two different DOCT measurement systems were utilized in the experiments: a commercial conventional OCT system and a laboratory-built DOCT system, intended particularly for flow velocity measurements. In the laboratory-built DOCT system, depth scanning was achieved by moving the whole measurement system with the reference mirror fixed. This modification from a conventional OCT system improves lateral resolution during the scanning process. A syringe pump was used to induce flow in the capillary. Flow velocity was measured with flow rates from 1 ml/min to 3.33 ml/min using both measurement systems. For a flow rate of 3.33 ml/min, both systems gave reasonable results. For flow rates lower than 3.33 ml/min, however, the laboratory-built DOCT system gave much better results. Its mean measurement error was as low as 0.8 %, while that of the commercial OCT was 6.8 %. Measured with the laboratory-built DOCT system, capillary force-induced flow velocity in the microfluidic channel was around 2 mm/s. The commercial OCT system, on the other hand, proved unsuitable for flow measurements in the microfluidic channel due to its high scanning speed.