Figure 2

Hydration dependence of the static deflection and the fundamental resonance frequency of cantilevers for increasing packing density of the ssDNA SAM. (a) Cantilever static deflection variation during a hydration and dehydration cycle for a representative gold-coated silicon cantilever sensitized with thiol-modified 20-mer ssDNA molecules. For comparison, the hydration/dehydration loop for the gold-coated cantilever before functionalization is also shown (dark yellow line). The static deflection variations are measured with respect to the rest position at a relative humidity of 0%. (b) Cantilever fundamental resonance frequency variations as a function of the relative humidity for increasing incubation times ranging from 5 min up to 24 h. For comparison, we show the hydration/dehydration loop for the gold-coated cantilever before immobilization. Measurements were acquired simultaneously to those in (a) for each cantilever at every given incubation time. The resonance was measured by a homemade detection system, see Supplementary Information. (c) Values of the deflection (blue symbols) and the frequency shift (red symbols) at RH 70% as a function of the immobilization time.