Fig. 8From: Label-free biosensing of Salmonella enterica serovars at single-cell levelThe 4D histograms constructed from force values and their extension values of APT33 (a) and APT45 (b) under seven loading rates, 1, 10, 20, 50, 100, 200, and 400 nN s−1. The color bars represent the normalized frequencies for the data points. The different sizes of the data points are proportional to their colorBack to article page