Figure 29.

SEM images of microfabricated post arrays showing improvements in the fabrication process. (A) 1 μm diameter, 150 nm tall posts appearing in 1992;³¹² (B) 200 nm diameter, 600 nm tall posts appearing in 2004;³⁴⁰ and (C) 300 nm diameter, 15 μm tall posts appearing in 2006.³⁴¹ Reprinted with permission from Refs.^312,340,341 Copyright 1992 Nature Publishing Group;³¹² 2004 American Chemical Society;³⁴⁰ 2006 Institute of Physics Publishing.³⁴¹