Figure 8.

(a) Cross-section Scanning Electron Microscopy image of a structure fabricated using two consecutive deep reactive ion etch steps. The bottom width corresponds to the original mask width (150 μm) but the entrance of the structure has been widened. (b) High contrast scanning electron microscopy image of a micro-channel fabricated by four consecutive deep reactive ion etch steps (Bosch) followed by anisotropic etching in KOH. The lines defining the ribs of the inverted pyramid extend from each corner to the bottom of the taper suggesting that the four delimiting walls are at 54.7° with respect to the plane.