In a subset of flow test experiments, 200nm diameter green fluorescent polystyrene particles (Molecular Probes F8888) are added to the alginate stream at 0.001% weight fraction. This assists visualization of the otherwise nearly transparent gels. At the end of these flow tests, ∼ 10 rods are carefully collected from the outlet of the device using a pipette, and then placed in a solution of 100mM calcium chloride within a 96-well plate for imaging. Fluorescent images are then captured at 20x magnification.