Fig. 8: Experimental results of protein adsorption on the wrinkled PMMA film.

a Surface morphology of the wrinkled PMMA film observed by a dark-field optical microscope. b Spectral SPR image of the wrinkled PMMA film before BSA adsorption. c RW image extracted from the hyperspectral SPR datacube acquired before BSA adsorption. d 2D thickness distribution of the wrinkled PMMA film. e Thickness distribution along the dotted line in Fig. 8d, showing the valley depth ≥ 5 nm. f 2D distribution of RW difference (ΔRW). ΔRW at a pixel is obtained by subtracting the RW before BSA adsorption from the RW after BSA adsorption at the same pixel. g 2D distribution of the BSA adlayer thickness. h BSA adlayer thickness fluctuation along the dotted line in Fig. 8g. The peaks of adlayer thickness correspond to the dips of PMMA film thickness in Fig. 8e. i Five-layer Fresnel model used for calculating BSA adlayer thickness. The similar results were obtained with two PMMA-coated SPR chips.