Figure S12. Picture shows the basic structure of pNIPAm microgel-based etalon composed of a monolith of microgel layer (II) sandwiched between two gold layers (I and III) on a support glass substrate (IV). To fabricate etalon chips, first, PNIPAm-based microgels containing 10% acrylic acid (AAc) (pNIPAm-co-10%AAc) were prepared by free radical precipitation polymerization of the monomer NIPAm with N,N′-Methylenebis(acrylamide) (BIS) as the crosslinker and AAc as a comonomer. The resulting microgels have a size about 750 nm in diameter. For the etalon chip, 2 nm Cr and 15 nm Au layer were subsequently coated on to the glass slides using thermal evaporator. A layer of microgel was coated and then another 15 nm Au layer was deposited.