Fig. 3. Orifice reduction yields thin and fast jets for low-background imaging and megahertz SFX with low sample consumption.

a GDVN CAD drawing and critical orifice design parameters that determine jetting performance are gas aperture, spacing, and sample aperture. While the all 30 µm orifice developed reliably during an overnight incubation, the all 20 µm nozzle frequently failed to fully develop even after a week of incubation in PGME developer. Introducing a slit aperture combined efficient overnight development with improved gas focusing performance. b Characteristic jetting modes were inferred from maximum intensity projections from ten jet image frames to highlight temporal deviations from the central jet axis (Supplementary Movies 2–5). A (1) stable jet (dot) continuous without fluctuations even after the drop break-up region indicated by a black arrow. A (2) metastable jet (open circle) exhibits occasional instabilities that cause droplets to be ejected in random directions off the central jet axis. An (3) unstable jet (cross) whips around the central axis. c–e Jetting phase diagram for the 14 × 45 µm gas orifice design with the colored section highlighting the stable jetting region. Jet parameters were measured and averaged over ten images for each flow rate combination to interpolate heat maps. c Dual pulse iLIF illumination measured jet speeds at 1 mbar vacuum (Supplementary Fig. 3) and d observed jet lengths. e Corresponding jet diameters calculated from measured jet speeds and water flow rates. Fast stable jets (4) of 177 ± 13 m s⁻¹ speeds were observed at helium gas flow rates of 22.5 mg min⁻¹ and water flow rates of 2.4 µl min⁻¹ and a jet diameter of 534 ± 35 nm and length of 59 ± 12 µm.