Artificial Piezoelectric Interface Enables Ultrafast Interfacial Ion Kinetic for Highly-Sensitive Piezoionic Sensors.

Flexible piezoionic sensors are promising in artificial intelligence and biomedical engineering, while presenting low signal, delayed response, and limited sensitivity. This is mainly because the ion migration kinetics is sluggish at electrode/electrolyte interface inside all-solid-state piezoionic sensors during the sensing process. Here, an artificial piezoelectric interface is engineered into flexible sensors to enable systematic regulation of piezoionic response behavior. The built-in electric field based on the piezoelectric interface layer significantly promotes ion migration and strengthens charge enrichment at the electrode/electrolyte interface. As a result, the piezoionic sensor achieves a 16-fold enhancement of sensing voltage, and delivers excellent performances over previously-reported similar flexible sensors, such as rapid response and recovery time, high conductivity, excellent linearity, and good durability. Furthermore, wearable applications of piezoionic sensors are demonstrated in various scenarios, including human motion monitoring and human-machine interaction. This study presents an insight into interface engineering in advancing flexible electrochemical devices.