Fig. 3: Stretchable and double-layer wires on LPT.

a Schematics showing that PP-infiltrated textile surface stabilizes wire interfaces, while the original textile suffers from debonding at wire interfaces. The red semi-circle indicates the position of textile yarn before stretching. b FTIR spectra of the bulk PP from partial polymerization, with an inset highlighting the hydroxyl and amine stretching regions of both the PP and the original textile. c Photos of LM wires on different textile substrates before and after cyclic stretching. d Comparison between resistance variations of LM wires on original and PP-infiltrated textiles during cyclic stretching. e Schematics showing the effect of thickness of suspended LM wires on their resistance to break. The red semi-circle indicates the position of textile yarn before stretching. f, g (f) Photos and (g) resistance variations of stretched LM wires on textiles, which are fabricated using varied stencil masks. h Resistance variations of an LM wire (length: 20 mm; width: 1 mm; mask thickness: 50 μm) on a PP-infiltrated textile during 1000 stretch cycles. i Schematics showing that VIB induced by programmed stiffness prevents short circuits between LM wires on the opposite sides of textiles. In contrast, soft textiles develop vertical gaps under compressive strains, leading to cross-layer short circuits. VIB, vertical interconnect block. j Comparison between compressive displacements of PP-infiltrated textiles programmed at varied laser speeds. Laser power: 21.5 mW; Line spacing: 40 μm. Error bars are presented as mean ± SD for n = 4 independent experiments. k Compressive stress of VIBs produced by varied laser speeds, measured until short circuits occur. The marks indicate short circuits. Y: yes; N: no. Laser power: 21.5 mW; Line spacing: 40 μm. l Compressive stress of a stiff VIB during cyclic pressing, and no short circuit occurs in the meantime.