Figure 1. Laser-induced 3D helical TVFs generation and characterization via single-particle tracking. (IMAGE)
Caption
Figure 1. Laser-induced 3D helical TVFs generation and characterization via single-particle tracking. (a) Schematic of the experimental setup: a mildly heating infrared laser beam is rapidly scanned across a fluid sample. The inset conceptually depicts the resulting helical flow profile. (b) Illustration of the sample chamber cross-section, assembled from two identical glass coverslips, with the laser scanning plane positioned near the top glass surface, which leads to the observation of pronounced helical flows (shown in the lower panel). (c) A representative measured 3D single-particle trajectory reveals that the 3D TVFs contain a helical structure that simultaneously transports and rotates the particle. The scan area spans approximately 68 µm in the x-direction and 7.6 µm in the y-direction, discretized into 400 steps in x and 50 steps in y, resulting in 20,000 scan points per full scan cycle. The laser scanning frequency is fixed at 500 kHz, which corresponds to an overall scan repetition rate of 25 Hz for the complete scan pattern.
Credit
Prof. Moritz Kreysing et al.
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CC BY