  Next-generation implantable computational devices require long-term stable
electronic components capable of operating in, and interacting with,
electrolytic surroundings without being damaged. Organic electrochemical
transistors (OECTs) emerged as fitting candidates. However, while single
devices feature impressive figures of merit, integrated circuits (ICs) immersed
in a common electrolytes are hard to realize using electrochemical transistors,
and there is no clear path forward for optimal top-down circuit design and
high-density integration. The simple observation that two OECTs immersed in the
same electrolytic medium will inevitably interact hampers their implementation
in complex circuitry. The electrolyte's ionic conductivity connects all the
devices in the liquid, producing unwanted and often unforeseeable dynamics.
Minimizing or harnessing this crosstalk has been the focus of very recent
studies.
  In this Perspective, we discuss the main challenges, trends, and
opportunities for realizing OECT-based circuitry in a liquid environment that
could circumnavigate the hard limits of engineering and human physiology. We
analyze the most successful approaches in autonomous bioelectronics and
information processing. Elaborating on the strategies to circumvent and harness
device crosstalk proves that platforms capable of complex computation and even
machine learning can be realized in-liquido using mixed ionic-electronic
conductors.
