Fig 1.
Working principle of active droplet formation.
(a-c) Digitally-driven quasi-isotropic pigment injection within Hele-Shaw fluid cell. (d-e) Anisotropic droplet formation over time achieved through dynamic control of flow field.
Fig 2.
(a) Reversible pigment droplet dispersal and retraction under quasi-isotropic flow field. Images show fifth dispersal/retraction sequence of fifty similar sequences. (b) Droplet area as a function of droplet radius, where droplet area is proportional to dispersed volume, for reversible droplet dispersal and retraction sequence. (c) Droplet interface (perimeter) as a function of droplet radius for reversible droplet dispersal and retraction sequence.
Fig 3.
Pigment dispersal across variable anisotropic flow fields.
(a) Four Hele-Shaw cell states with spatially-varied outlet boundary conditions. (b) Estimated (idealized) steady-state potential flow field from cell configurations in a. (c) Overlaid time-series images demonstrating anisotropic droplet growth over time. (d) Final droplet configuration from c with overlaid gradient vector field from b.
Fig 4.
Time-dependent droplet growth under four unique potential flow fields (a-d).
Fig 5.
Non-normalized (a) single-outlet and (b) multioutlet droplet deformation as a function of time (left graphs) and area-normalized droplet deformation as a function of fractional area coverage (right graphs), proportional to dispersed pigment volume (flow rate = 25 mL/min).
Fig 6.
Circular droplets become more square-like over time.
Quad-outlet droplet deformation as a function of fractional area coverage, proportional to dispersed pigment volume (flow rate = 25 mL/min), for both (a) corner outlet configuration and (b) edge midpoint outlet configuration.
Fig 7.
Multiport time-dependent droplet migration due to a hydrodynamic potential.
Fig 8.
Fabricated and simulated multipixel visual displays.
(a) Image of a built quad-cell display, where each array element demonstrates a unique flow field and pigment droplet morphology (t = 100 s after injection). (b) Examples of switchable digitally-generated multicell displays (unbuilt). (c) Simulated pattern emergence to achieve a predefined multicell visual array (d). Static flow field displayed next to corresponding pigment cell. Assuming a cell length of 20 cm, the visualized 40x40 cell display could stretch 8x8 m2.
Fig 9.
Differential visible and near-infrared light transmission between the aqueous pigment phase (grey curves) and oil phase (red curve) for a 3 mm optical path length. Grey curves represent varied concentrations of aqueous carbon black suspensions, where values describe concentration in g of C per 50 mL of H2O.