Ion flow crossing over a polyelectrolyte diode on a microfluidic chip.

Key evidences are reported for the rectification mechanism of an aqueous ion diode based on polyelectrolytic plugs on a microfluidic chip by monitoring the ion flow crossing over the junction. The ion flow penetrating the polyelectrolyte junction is visualized by employing a fluorescent chemodosimeter, rhodamine B hydrazide and the pH-dependent dye, carboxy-fluorescein. How hysteresis phenomena, exhibited through the nonlinear behavior of the polyelectrolyte diode, are affected by a variety of parameters (e.g., switching potential, scan rate, and electrolyte concentration) is also investigated. The insights and knowledge from this study provide a crucial foundation for ion control at the iontronic diode in the aqueous phase, leading to more advanced aqueous organic computing devices and more diverse applications for microfluidic logic devices.