Stretchable and compressible piezoresistive sensors from auxetic foam and silver nanowire

Progress in Auxetic Mechanical Metamaterials: Structures, Characteristics, Manufacturing Methods, and Applications

“…Generally, PU foams are inserted into the mold, biaxial or triaxial compressed, heated above the softening temperature, and then cooled to room temperature for fabricating foams with auxetic behavior in stretching. [94][95][96][97]150] This process is capable of developing the common open-cell voids into re-entrant shape. There are also studies on the preparation of auxetic copper and silicone foams using this technique.…”

“…The hot‐compression method is the most common method of the fabrication of auxetic foams made from conventional PU foams. Generally, PU foams are inserted into the mold, biaxial or triaxial compressed, heated above the softening temperature, and then cooled to room temperature for fabricating foams with auxetic behavior in stretching . This process is capable of developing the common open‐cell voids into re‐entrant shape.…”

“…It was also found that the sensing sensitivity of the auxetic foam sensor in water was about twice than that in air. Similarly, CNT sensing material could be replaced by metallic sensing materials, such as silver nanowire (AgNW) . Kim et al created an auxetic hygroscopic strain sensor using AgNW as sensing material, which could match with the deformation of the skin in ankles and absorb sweat to improve breathability.…”

Strain Sensor with Enhanced Sensitivity for Wearable Electronics Using an Over‐Balanced Planar Elastomer

“…How to regulate the shrinkage effect based on the tunable Poisson's ratio of materials has been first reported in the seminal work of Lakes based on the classical elastically theory in 1987, [22] and then the elastic instability mechanism has been investigated. [23] Nowadays, many kinds of geometries and mechanisms have been proposed to achieve such effect, [24][25][26] and the typical structures adopted in the stretchable sensors are Kirigami structures [27][28][29] or auxetic architectures. [30][31][32] However, these structures are relatively complex and usually constructed using complicated manufacturing processes, which make a bottleneck in the practical development towards applications.…”

Additively manufactured AlSi10Mg inherently stable thin and thick-walled lattice with negative Poisson’s ratio

“…Auxetic behaviour is receiving increasing attention due to its desirable effects such as enhanced shear modulus [6][7][8][9], resistance to impact [10][11][12][13][14], indentation [15][16][17][18], fracture toughness [19][20][21][22], and damping properties [23][24][25]. These performances then translates to applications such as novel fasteners [26,27], foams [28][29][30][31][32][33][34], biomedical implants [35][36][37][38] and actuators [39][40][41].…”