All-Atom Molecular Dynamics Simulations of Communication Between Nanochannel Arrays

Abstract

The stacking of nanochannels in an array is a promising method for scaling nanoscale phenomena to large-scale systems. However, the scalability of single-nanochannel transport characteristics to a large-scale system (i.e., nanochannel arrays) is limited due to interchannel communications. Here, we report the communication between nanochannels in the array using an all-atom molecular dynamics (MD) simulation. In this simulation, a silicon nitride nanochannel array is integrated with the bulk reservoirs, and an electric field is applied across the reservoirs. Intriguingly, the simulations reveal a distinct pattern of communications between nanochannels and are mapped for the first time in the ohmic and nonohmic regions. In the ohmic region, individual channel current increases from the center channel to the channel near the boundary of the reservoir. Surprisingly, this pattern is reversed for the nonohmic region and the center channel shows a higher current compared to the other channels. This behavior may be attributed to the electro-osmotic instability (EOI) controlling the different length propagation of the extended space charge region into the individual channels. Further, we show the scaling law of the nanochannel conductance with the number of channels in both regions. This study offers useful insights for designing nanochannel arrays to improve the process efficiency of applications such as power generation, desalination, drug delivery, ionic logic gates, and circuits.

Ion Transport in Multi-Nanochannels Regulated by pH and Ion Concentration

“…In general, interactions between nanochannels in an array are based on the competition for ionic access that occurs outside the nanochannel at the entrances of the nanochannels. , Overlapping access resistance zones are formed at the entrances of the nanochannels and access resistances do not simply add in parallel . The overlapping ion depletion zones and diffusion profiles of neighboring nanochannels may also limit the conductance of the overall array. ,, The above results affirm the occurrence of interactions between nanochannels, which have also been explored in previous studies. , In the following discussions, we investigate the difference in electrokinetic ion transport under different background solution conditions (pH values and salt concentrations), the number of nanochannels, and the distance between adjacent channels, which have not been discussed before.…”

“…55, 57,58 The above results affirm the occurrence of interactions between nanochannels, which have also been explored in previous studies. 37,59 In the following discussions, we investigate the difference in electrokinetic ion transport under different background solution conditions (pH values and salt concentrations), the number of nanochannels, and the distance between adjacent channels, which have not been discussed before.…”

“…When the extended space charge (ESC) area is subjected to an electric field, electro-convective vortices often form in the vicinity of ion-selective nanochannels. 5,59 Ionic concentration polarization is the cause of electro-convective vortices. An iondepleted zone, or concentration polarization layer, is created when the electrolyte solution's ions flow through the nanochannel as a result of the selective adsorption of electrolyte ions on the channel's surface.…”