Close investigation of the microscopy imaging and simultaneous pressure traces reveals several interesting features of the deposition/ablation process. Comparison of the pressure measurements with microscopy suggests that the deposition occurs both at and immediately downstream of the junction between the alginate and calcium streams. During alginate deposition, the alginate gel deposits and grows on the channel wall in the first 500-1000 µm after the junction, as seen in Fig. . While ∆P accounts for deposition anywhere in the channel, the close correlation between the microscopy and ∆P indicates that any deposition activity more than ∼ 1 mm downstream of the junction, beyond the field of view of the microscope image, has little effect on ∆P . Further microscopic investigation using z-stack microscopy suggests that the alginate gel deposits on all surfaces within the channel (SI Fig. ). Coating the glass slide with PDMS reveals that deposition occurs on the PDMS (SI Fig. ). Further, varying the device orientation with respect to gravity does not change the clogging pattern (SI Fig. ). This confirms that gel attachment on the wall of the device occurs independently of gravity and suggests that the build-up of gel happens by the diffusion of the crosslinked polymer to the surface of the growing gel layer on all sides .