Applications of auxetic metamaterials in other fields. (a) Schematic of an auxetic nail in insert and pull-out states [133]. (b) Interlocking NPR connectors design for deployable energy absorption structures [135]. (c) Flexible capacitive pressure sensor with fourth-order star-shaped NPR structure [136]. (d) Shoe midsole with 3D tetrachiral NPR structure [137]. (e) AMM structures and the corresponding capacitive and resistive tactile sensors [138].