Figure 4
From: Microfluidic Screening of Electric Fields for Electroporation
(a) Summed intensity (a.u., arbitrary units) versus distance from the channel center. The summed intensity at each point is equal to the sum of the intensity values in the (shaded) vertical column of pixels located at the point of interest. (b) Result of the one-sided two-sample Kolmogorov-Smirnov (KS) test as a function of position along the channel. The value of H at a given location indicates that the null hypothesis H0 was either accepted (H = 0) or rejected (H = 1) for a 51-pixel stencil centered at that location. As discussed in the main text, H = 1 for regions in which a significant portion of the post-pulse fluorescence intensity values exceed the pre-pulse values. In general, the location at which H changes from 0 to 1 is taken as the location of onset of fluorescence enhancement due to electroporation. For the case depicted above (C. glutamicum, Vapp = 1.8 kV), the predicted values of the critical electric field (found by linearly interpolating the simulated electric field data visualized in Fig. 2a,b) are 4.28 kV/cm (left) and 3.85 kV/cm (right), yielding an average Ecrit = 4.07 kV/cm. Note that in cases such as this, in which the entire channel is in the microscope’s field of view, it is possible to exploit the bilateral symmetry of the channel geometry and obtain two estimates of Ecrit – one on each end of the channel.
