Fig. 3

Fig. 3

Measurement in time of the blood flow speed in the hepatic microcirculation.

(a) xy-image acquired by detecting the photoluminescence (shown in white) of 5-nm QDs (λ_exc = 900 nm, detection bandwidth = 640–690 nm); f_line = 850 Hz, δx = 0.051 μm, scale bar, 10 μm. CCFs have been derived on the evidenced ROIs (ROI 1: 240 × 210 pixels; ROI 2: 450 × 120 pixels; ROI 3: 145 × 250 pixels) for (J-I)δx = 0.5–2 μm and fitted (equation (3)), leading to |v| = 235 ± 4 μm/s, 235 ± 3 μm/s and 229 ± 8 μm/s for ROIs 1, 2 and 3, respectively. A color coding is assigned for the speed |v|, while the arrows indicate the flow direction. γ, fixed to 50°, −4° and 80° in ROIs 1, 2 and 3, is sketched in the reference xy-plane. (b), (c) The xy-image in (a) is one out of ten frames of an xyt-stack (Δt = t_{i + 1}–t_i = 0.88 s is the interval between the sampling of the same pixel in two consecutive frames i and i + 1). The first five frames, each identified by its sampling time t_i = iΔt, are shown for ROIs 1 (b) and 2 (c). The same color code of panel (a) is adopted for the centreline. Scale bar, 5 μm; same calibration bar (in arbitrary units) in (b) and (c). (d), (e) Estimates for |v| (triangles) and |v|⁰ (squares) versus time in ROIs 1 (d) and 2 (e). The average ratio |v|/|v|⁰ is 0.92 and 0.95 in ROIs 1 and 2, respectively.