Effect of field-focusing and ion selectivity on the extended space charge developed at the microchannel-nanochannel interface.
We present results demonstrating the effect of varying microchannel depth and bulk conductivity on the space charge-mediated transition between classical, diffusion-limited current and over-limiting current in microchannel-nanochannel devices. The extended space charge layer develops at the depleted microchannel-nanochannel entrance when the limiting current is exceeded and is correlated with a distinctive maximum in the dc resistance. This maximum is shown to be affected by the microchannel depth, via field-focusing, and solution conductivity. In particular, we observe that upon their increase, the maximum becomes flatter and shifts to higher voltages.
Faculty of Mechanical Engineering, Micro- and Nanofluidics Laboratory, Technion-Israel Institute of Technology, Technion City 32000, Israel.
Uri
U
Liel
Neta
N
Leibowitz
Jarrod
J
Schiffbauer
Sinwook
S
Park
Gilad
G
Yossifon