This article presents the implementation of on-chip iontronic
circuits
via small-scale integration of multiple ionic logic gates made of
bipolar polyelectrolyte diodes. These ionic circuits are analogous
to solid-state electronic circuits, with ions as the charge carriers
instead of electrons/holes. We experimentally characterize the responses
of a single fluidic diode made of a junction of oppositely charged
polyelectrolytes (i.e., anion and cation exchange membranes), with
a similar underlying mechanism as a solid-state p- and n-type junction.
This served to carry out predesigned logical computations in various
architectures by integrating multiple diode-based logic gates, where
the electrical signal between the integrated gates was transmitted
entirely through ions. The findings shed light on the limitations
affecting the number of logic gates that can be integrated, the degradation
of the electrical signal, their transient response, and the design
rules that can improve the performance of iontronic circuits.