Pulstrodes: triple pulse control of potentiometric sensors.
Ion-selective electrode membranes based on hydrophobic materials doped with chemically selective host molecules are an attractive sensing technology but normally suffer from a limited sensitivity, given by the Nernst equation, and a direct reliance on the reference electrode potential, which makes miniaturization difficult. These fundamental problems are addressed here by imposing a multipulse electrochemical excitation signal onto ion-selective membranes that lack ion-exchange properties. Current pulses are responsible for the generation of ion fluxes in the direction of the membrane, which give reproducible super-Nernstian response slopes that originate from depletion processes at the membrane surface. Membranes may also be measured at zero current after this pulse, giving super-Nernstian response regions at lower concentrations. Difference potentials obtained from subsequent pulses give about 10-fold higher sensitivities than predicted on the basis of the Nernst equation.
Department of Chemistry, Auburn University, Auburn, Alabama 36849, USA.
Sergey
S
Makarychev-Mikhailov
Alexey
A
Shvarev
Eric
E
Bakker
D015374:Biosensing Techniques / Q000379:methods; D011199:Potentiometry / Q000379:methods*