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 (?_exc = 900?nm, detection bandwidth = 640?690?nm); f_line = 850?Hz, ?x = 0.051??m, scale bar, 10??m. 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)?x = 0.5?2??m and fitted (equation (3)), leading to |v| = 235 ± 4??m/s, 235 ± 3??m/s and 229 ± 8??m/s for ROIs 1, 2 and 3, respectively. A color coding is assigned for the speed |v|, while the arrows indicate the flow direction. ?, 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 (?t = 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 = i?t, are shown for ROIs 1 (b) and 2 (c). The same color code of panel (a) is adopted for the centreline. Scale bar, 5??m; 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.