Recently, artificial channel‐based ionic diodes and transistors are extensively studied to mimic biological systems. Most of them are constructed vertically and are challenging to be further integrated. Several examples of ionic circuits with horizontal ionic diodes are reported. However, they generally require nanoscale channel sizes to meet the demand for ion‐selectivity, resulting in low current output and restricting potential applications. In this paper, a novel ionic diode is developed based on multiple‐layer polyelectrolyte nanochannel network membranes. Both bipolar and unipolar ionic diodes can be achieved by simply switching the modification solution. Ionic diodes with a high rectification ratio of ≈226 are achieved in single channels with the largest channel size of 2.5 µm. This design can significantly reduce the channel size requirement and improve the output current level of ionic devices. The high‐performance ionic diode with a horizontal structure enables the integration of advanced iontronic circuits. Ionic transistors, logic gates, and rectifiers are fabricated on a single chip and demonstrated for current rectification. Furthermore, the excellent current rectification ratio and the high output current of the on‐chip ionic devices highlight the promise of the ionic diode as a component of complex iontronic systems for practical applications.

Bioinspired asymmetric two-dimensional (2D) nanochannels with ionic diode behavior are highly desirable, as they can be constructed and modified easily. However, the knowledge about the rectification mechanism of the nanochannels...

Much progress has been made in the electrokinetic phenomena inside nanochannels in the last decades. As the dimensions of the nanochannels are compatible to that of the electric double layer (EDL), the electrokinetics inside nanochannels indicate many unexpected behaviors, which show great potential in the fields of material science, biology, and chemistry. This review summarizes the recent development of nanofluidic electrokinetics in both fundamental and applied research. First, the techniques for constructing nanochannels are introduced to give a guideline for choosing the optimal fabrication technique based on the specific feature of the nanochannel. Then, the theories and experimental investigations of the EDL, electroosmotic flow, and electrophoresis of nanoparticles inside the nanochannels are discussed. Furthermore, the applications of nanofluidic electrokinetics in iontronics, sensing, and biomolecule separation fields are summarized. In Section 5, some critical challenges and the perspective on the future development of nanofluidic electrokinetics are briefly proposed.

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