Gate controlled EDL-based capacitor-diodes (G-CAPode) for switchable signal filters with logic gate functionality

This work explores a novel application of the G-CAPode – a previously developed, 3D-printed gate-controlled electrochemical capacitor-diode – by demonstrating its ability to perform logic operations in ionic circuits. The G-CAPode integrates diode-like rectification, voltage-controlled switching via a gate electrode, and dynamically tunable capacitance within a single architecture. While prior studies demonstrated G-CAPodes to function as tunable capacitors – a varactor – in high-pass filters, this study extends its use toward logic operations. Specifically, frequency-dependent OR and AND logic behaviors are realized by connecting two G-CAPodes in parallel and series, respectively. In these configurations, logic output is determined by the impedance state of each device, which is dynamically controlled via gate bias. The OR-gate circuit yields a high output when at least one G-CAPode is in the ON (low-impedance) state, while the AND-gate setup requires both devices to be ON for signal transmission, consistent with Boolean logic. The switching behavior is controlled by applying specific gate biases, which modulate the impedance of each G-CAPode in real-time and therefore enables analog logic functionality using purely ionic components. The results underline the potential of the printed G-CAPode as a multifunctional platform for adaptive signal processing, offering a compact and silicon-free solution for emerging iontronic applications such as neuromorphic computing, adaptive filtering, and analog signal processing.