fig8

From: Flexible iontronic pressure sensing technology: advanced structural ionic layer

Figure 8. Multi-hierarchical regularity structure. (A) The gel ionic layer having a two-level graded microstructure: periodic domes and dense finer protrusions on the domes. Reproduced with permission^[23]. Copyright 2023, Springer Nature; (B) Microcone array directly grown on the surface of the electrospun film ionic layer^[57]. Reproduced with permission. Copyright 2024, Elsevier; the structural design of ionic layers for (C) Microfrustum hierarchical arrays. Reproduced with permission^[153]. Copyright 2024 Wiley-VCH. TPU: Thermoplastic polyurethane; PDMS: polydimethylsiloxane; PET: poly(ethylene terephthalate); PVA: poly vinyl alcohol; [TFSI]: bis(trifluoromethanesulfonyl)imide; EMI: 1-ethyl-3-methylimidazolium; AC: alternating current; ΔC:capacitance variation.