Figure 1.

Schematic representation of the electrostatic regimes of hybridization on DNA microarrays. For the brush region, two electrostatic regimes I and VI exist, corresponding, respectively, to salt and counterion screening. For the mushroom region, we distinguish four different electrostatic regimes: II salt and V counterions screening of a two-dimensional array of penetrable charged spheres, and III salt and IV counterions screening of a two-dimensional array of pointlike charges.