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. 2020 Oct 26;117(45):27916–27926. doi: 10.1073/pnas.2016388117

Fig. 6.

Fig. 6.

Liquid capsule demonstrating on-demand liquid-cargo delivery in narrow tubes. (A) Video snapshots of the experimental procedures of loading, transporting and releasing liquid cargos. (A, i) The water-based liquid cargo (water-based food dye, ∼12 μL) is loaded on an FDR (∼195 μL) using a syringe injector. (A, ii) The FDR moves freely while carrying the liquid cargo without breaking. Yellow dashed lines: the trajectory of the FDR. (A, iii) The liquid cargo is released on demand using the splitting mechanism by controlling external magnetic fields. (B) X-ray images of an FDR with and without liquid cargos inside. The X-ray images show an FDR without liquid cargos (B, i), with one liquid droplet (B, ii), two liquid droplets (B, iii), and multiple liquid droplets inside (B, iv). (C) Sequential video snapshots demonstrating on-demand “drug delivery” in a vascular phantom model with narrow branches. The FDR carrying liquid cargos navigates through the phantom with varying inner diameters (4 to 8 mm), delivers liquid cargos (food dye) at a target location on a branch by splitting, and is retrieved after the task. In all experiments, the ferrofluids used were obtained by mixing ferrofluids with dynamic viscosities of 80 mPa·s (MFR-DP1; Supermagnet.de) and 8 mPa·s (EMG 901; Ferrotec Corporation) according to a volume ratio of 1:1.