Probing surface charge fluctuations with solid-state nanopores.
We identify a contribution to the ionic current noise spectrum in solid-state nanopores that exceeds all other noise sources in the frequency band 0.1-10 kHz. Experimental studies of the dependence of this excess noise on pH and electrolyte concentration indicate that the noise arises from surface charge fluctuations. A quantitative model based on surface functional group protonization predicts the observed behaviors and allows us to locally measure protonization reaction rates. This noise can be minimized by operating the nanopore at a deliberately chosen pH.
Hoogerheide
David P
DP
Physics Department, Harvard University, Cambridge Massachusetts 02138, USA.
Garaj
Slaven
S
Golovchenko
Jene A
JA
D004553:Electric Conductivity; D004566:Electrodes; D006863:Hydrogen-Ion Concentration; D046529:Microscopy, Electron, Transmission; D008956:Models, Chemical; D049329:Nanostructures / Q000737:chemistry*; D009994:Osmolar Concentration; D017655:Silicon Compounds / Q000737:chemistry; D012834:Silver / Q000737:chemistry; D018030:Silver Compounds / Q000737:chemistry; D013499:Surface Properties
D017655:Silicon Compounds; D018030:Silver Compounds; D012834:Silver; C037548:silver chloride; C032734:silicon nitride