Fig. 2.

The resolution of internal features can be increased by making changes to the light source, resin viscosity, and print layer height. (A) A test piece had six internal channels, 9-mm long with 0.75 mm diameter inlets and varied channel cross-sections as noted. It was printed with (B-D) (i) 50 μm layer height or (ii) 100 μm layer height, as follows: FormLabs Clear resin was printed with a (B) 405 nm or (C) 385 nm light source; (D) for comparison, a low viscosity resin, BV007a, was printed at 385 nm. Other settings were left unchanged, with the exception of increasing exposure times slightly for some 100-μm prints (Table S1). Resolution was determined visually by observing the smallest channel cross-section that could be printed fully (pink arrows) or partially open (purple arrows).