Figure 2.

Schematic illustration of a 2D photonic crystal sensor formed by polymerization of a pNIPAm hydrogel network onto a 2D array of 490 nm PS particles, which was added to a liquid Hg surface. The pNIPAm hydrogel swells upon binding of surfactant molecules. The 2D particle spacing increases upon swelling of the pNIPAm hydrogel, red shifting the diffracted wavelength. Reprinted with the permission of [46] Copyright ^© 2012, American Chemical Society.