Fig. 4. Data-driven identification of tip–sample interaction as a function of tip–sample separation on PS-LDPE sample. (a and b) Phase and topography images of PS-LDPE blend sample, respectively. The blue contour indicates the LDPE islands and the orange contour the PS matrix. (c) Experimental dynamic spectroscopy signal obtained with 80% set-point ratio on LDPE material. The dashed lines indicate specific tip–sample distances at which data-driven identification is performed. The distances as read from left to right are at 85 nm, 72.7 nm, 67.2 nm, 58.2 nm, respectively. (d) Experimental deflection signal obtained from averaging 15 periods at different tip–sample sample distances. (e) Identification of tip–sample force based on the data-driven model at different tip–sample distances. (f) Experimental dynamic spectroscopy signal obtained with 80% set-point ratio on PS material. The dashed lines indicate specific tip–sample distances at which data-driven identification is performed. The distances as read from left to right are at 85 nm, 72.6 nm, 67.1 nm, 64.1 nm, respectively. (g) Experimental deflection signal obtained from averaging 15 periods at different tip–sample distances. (h) Identification of the tip–sample force based on data-driven model at different tip–sample sample distances.