Fig. 1: Flow confinement within the μkiss paintbrush.
a, Schematic of a micropipette pair for coating live cells. b, Image of the micropipette pair with an inset showing a SEM image of the tapered micropipettes with an inner diameter of 6 μm and their angular displacement of 35°. Scale bar 5 mm, inset 5 μm. c, Numerical simulation of the confined flow (green) with the direction of fluid streamlines overlaid (blue) for the geometry in b. Scale bar 5 μm. d,e, In-stream flow lines and velocities for gold nanoparticles (diameter, 80 nm) in simulation (d) and experiment (e) for Qinj = 0.11 nl s−1 and Qratio = 0.27. Scale bars 5 μm. f, Simulated stream velocities along line Le shown in the inset for various flow rate ratios Qratio at Qin = 0.16 nl s−1. g, Envelope extent for various flow ratios and absolute volumetric flow in both simulation and experiment. h, Image of a pattern generated on a glass coverslip by controlled deposition of 200 nm fluorescent beads. Scale bar 20 μm. i, Simulated shear stress in the vicinity of the apertures. Dashed lines mark the envelope boundary for Qinj = 0.16 nl s−1 and Qratio = 0.3. Scale bar 5 μm.
