Fig. 2.

Characterization of the anisotropic etching (the 1st DRIE) process to create microwell structures a Microwell diameter (d) and pattern-to-pattern gap (g) are shown as design parameters of a photomask. b A SEM image shows cross-sectional view of the microwells fabricated by 250 cycles of anisotropic etching (d = 70 μm and g = 30 μm). c Etched depths of microwells are plotted as a function of the 1st DRIE cycle numbers for 50, 70, and 100 μm in microwell diameter. d Depth of microwells etched by 250 DRIE cycles as a function of pattern-to-pattern gaps ranging from 10 to 100 μm. Microwell diameter was fixed at 50 μm