Fig. 2. Effect of geometry and surfactant concentration on success rate of TVs. a) Front view of food dye solution stopped at TV showing the TV height (h), width (w), and the height difference between TV and release channel (Δh). b) Success rates for TVs over a wide range of widths and heights. N = 8. c) Above a height difference (Δh) of 300 μm, TVs were 100% successful. N = 6. d) TVs were 100% successful at Tween® 20 concentrations ≤0.0650% weight/volume in 1 × PBS. N = 3.