Fig. 1. Principles of graded intrafillable architecture (GIA) design and the sensing mechanism.

a Stress distribution of simulation results for different architectures under pressures up to 400 kPa: a hemisphere; a tilted pillar, an intrafillable pillar without gradient, and the GIA. b Contact area variation between the dielectric layers with different architectures and an opposing electrode under a broad sensing range (0–400 kPa). c Schematic illustration for the functioning of the iontronic pressure sensor before and after applying pressure. d Schematic illustration of the preparation of a GIA-based iontronic pressure sensor. e A 45° tilt-view and f cross-sectional view SEM images of the PVA/H₃PO₄ GIA film, showing grooves and undercuts.