Measuring flow velocity distribution in microchannels using molecular tracers

Abstract

We demonstrate the capability of a molecular tracer based laser induced fluorescence photobleaching anemometer for measuring fluid velocity profile in microfluidics. To validate the feasibility and accuracy of this measurement system, the velocity profiles of the cylindrical and rectangular microchannels are measured, respectively. We compare our experimental results with theoretical prediction. The theoretical prediction shows a good consistency with practical measurement results. The spatial resolutions are analyzed and validated. Finally, the error source of the presented system is analyzed, which makes it possible to compensate some error quantitatively and guides the application of this system.

Ultrafast measurement of transient electroosmotic flow in microfluidics

“…The transient variation of EOF velocity u was recorded at the detection point, when a fast step of voltage increase was supplied to drive the flow in the microcapillary. In LIFPA, the higher the flow velocity, the larger the fluorescence signal (Kuang et al 2009b;Wang 2005). As shown in Fig.…”

“…Here, although the fluorescence signal was not converted to velocity by a pre-calibration relation, it does directly reflect the variation of transient velocity at the detection point-the focus of this work, since the fluorescence signal increases with the increased flow velocity, when other parameters are given (Kuang et al 2009b;Wang 2005). Quantitative determination of the velocity can be obtained through a calibration and is documented in our prior publications (Kuang et al 2009b;Wang 2005). Figure 2b shows the transient process with time step of 1 ls during a 10 ls period.…”

A novel far-field nanoscopic velocimetry for nanofluidics

“…[47][48][49]51 Concurrently the LIFPA is a promising technique for velocity measurement. 43,53 Applying STED to LIFPA could establish a new method for nanoscopic velocity measurement that can 'side-step' the classical optical diffraction limit.…”

“…[40][41][42][43] In LIFPA, a molecular tracer of fluorescence dye and the photobleaching effect are applied as a transducer to measure the flow velocity. The velocity is calculated by measuring fluorescence with a calibration relationship between the velocity and fluorescence.…”

Digital Micro PIV (μPIV) and Velocity Profiles In Vitro and In Vivo

“…Keeping the same definition in rectangular microchannels, the longest (horizontal) side of the cross section is usually referred to as "width" (W) and the shortest (vertical) as "height" (H). Research groups all over the world have studied flows inside microchannels with various ARs: 1 (W = 100 m, H = 100 m, Lima et al, 2006), 1.7 (W = 80 m, H = 48 m, Kuang et al, 2009), 4 (W = 800 m, H = 200 m, Lindken et al, 2006;W = 20mm, H = 5mm, Timgren et al, 2008), 6.7 (W = 300mm, H = 45mm, Lima et al, 2008) and 10 (W = 300 m, H = 30 m, Meinhart et al, 1999).…”