Geometrical control of ionic current rectification in a configurable nanofluidic diode

Area of Science:

• Nanofluidics
• Ionic current control
• Device physics

Background:

• Ionic current control in nanofluidic systems is crucial for developing electrical circuit analogs.
• Previous research focused on theoretical and experimental investigations over the past decade.
• Developing efficient rectification techniques is key for nanofluidic applications.

Purpose of the Study:

• To explore a novel technique for ionic current rectification using asymmetric 2D nanochannels.
• To investigate the effect of nanochannel geometry on rectification efficiency.
• To develop a theoretical model for predicting nanofluidic diode behavior.

Main Methods:

• Theoretical modeling using the 1D Poisson-Nernst-Planck equation.
• Validation of the 1D model against 2D numerical simulations.
• Experimental fabrication and testing of stepped 2D nanochannels.
• Analysis of ionic current rectification under varying electrolyte concentrations.

Main Results:

• Asymmetric 2D nanochannels with stepped structures achieve significant ionic current rectification.
• A nondimensional concentration parameter predicts optimal rectification at specific electrolyte concentrations.
• The rectification factor peaks at a certain concentration and decreases on either side.
• Experimental results align well with the developed 1D theoretical model.

Conclusions:

• Stepped asymmetric nanochannels provide an effective method for nanofluidic ionic current rectification.
• The developed model accurately predicts rectification behavior based on channel dimensions and electrolyte concentration.
• This technique allows for rectification control without surface charge modification, facilitating integration into lab-on-a-chip systems.