The piezoionic diode: field-driven amplification of mechano-ionic conversion

Piezoionics is a promising new paradigm for integrating soft electronics with biological systems for applications such as self-powered tactile sensing, neural interfaces, and energy harvesting. However, conventional piezoionic devices lack the capability to actively drive ion-counterion separation, leading to low outputs. Herein, we present a piezoionic effect diode (PIED), a new category of self-powered stimulus-response piezoionic devices. When subject to mechanical stimulus, the device's built-in electric field drives ion separation and directional ion transport, resulting in an amplified device output. The fabricated piezoionic effect diode achieves enhanced mechanoelectrical conversion efficiency, delivering an output of 30.5 mV (12.3× enhancement) and 2.46 µA (27.3× enhancement) with a maximum power density of 20.7 nW cm^-2. Importantly, its ionic rectification properties (ratio = 7.8) enable logic functions for in-sensor digital computation. Functioning as a self-powered smart tactile sensor, the PIED converts mechanical stimuli into neural-like spike signals. This work adds a new device category to piezoionics, enabling the field to serve both self-powered sensing and neuromorphic computation.