Hybrid systems of three‐dimensional carbon nanostructures with low dimensional fillers for piezoresistive sensors

Abstract

As an alternative of single filler system, hybrid fillers system is beneficial for the fabrication of elastomer‐based piezoresistive strain sensors with high strain sensitivity for structural health monitoring and human motion detection. However, a comprehensive understanding for the effect of the secondary filler dimensionality on piezoresistive strain sensor sensitivity by hybrid carbon nanofillers strategy is missing. Here, we report a comparative study about the effect of branched carbon nanostructures (CNS, three‐dimensional, 3D) combined with carbon black (CB, 0D) or carbon nanotubes (CNT, 1D) on the piezoresistive behavior of thermoplastic polyurethane (TPU)‐based composites. At either the same total filler content or similar electrical resistivity, using CNS‐CB hybrid is more efficient than using CNS alone or CNS‐CNT hybrid for improving piezoresistive sensitivity of the TPU composites. For instance, the composite 1.5CNS‐1CB has a gauge factor (GF) of 21 and 99 at strain ε = 50 and 100%, respectively, while the composites 2.5CNS and 1.5CNS‐1CNT have GF values of 4.3 and 9.1 at strain ε = 50% and 14 and 20 at strain ε = 100%, respectively. Besides, the TPU composite with CNS‐CB shows a larger response to finger bending (50° on an index finger) by comparison with that contains only CNS, indicating potential applications for human motion detection. This study introduces a facile way to fabricate strain‐sensitive sensors aimed at strain of 50%–100%, strengthening understanding the selection of hybrid carbon nanofillers with different dimensionalities to optimize piezoresistive sensor design.

Thermoplastic polyurethane/graphene nanosheets composites with reduced microplastics release and enhanced mechanical properties

“…[ 17 ] The versatility of TPU enables it to be commonly used in various applications, such as automobiles, aerospace, packaging materials, and many kinds of injection molding products. [ 18 ] As a consequence, TPU is a good candidate for the investigation on microplastics release of plastic products. Moreover, GNs have attracted tremendous attention due to their excellent physical‐chemical properties, [ 19,20 ] including high modulus, ultrahigh surface area, barrier capability and good electrical conductivity, and so on.…”

Hybrid‐Filler Stretchable Conductive Composites: From Fabrication to Application

“…[ 30 ] When the composite is stretched, the metal particles will separate from each other and thus the conductivity decreases drastically ( Figure A). [ 31–33 ] In contrast, the electrical conductivity of composites filled with fillers of high aspect ratio generally has low strain sensitivity. Flake‐shaped fillers can overlap like pages in a book.…”

“…[ 45 ] But it has the same disadvantage as metal particles, that is, the CB‐filled composite shows a sharp ascent in resistance during stretching. [ 32,46 ] CF is a high‐strength micrometer‐sized fiber material that has good resistance to corrosion and fatigue. [ 47 ] But its electrical conductivity is relatively low compared with CB and CNTs, so it is mainly used to enhance the mechanical strength of composites.…”

“…[ 41,55 ] These secondary fillers can also adjust the strain sensitivity of the composite. [ 32,36 ] Conversely, particulate secondary fillers (e.g., CBs and AgNPs) can also fill the gaps of primary fillers (e.g., CNTs and silver microplates) to reduce junction resistance and increase conductivity [7d,8d] . Some researchers have also bridged the primary fillers using small‐sized metal nanowires (NWs) to achieve the same purpose [7e,56] …”

Effect of conductivity transportation from carbon nanotubes (CNT) to polymer matrix surrounding CNT on the electrical conductivity of nanocomposites

“…The significant conductivity and stiffness of carbon nanotubes (CNTs) cause the conductive and stiff polymer nanocomposites (PCNTs) at or above a critical filler concentration as percolation threshold, because the CNT networks are established at this point [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] . So, the percolation threshold is an important term, which manages the conductivity of nanocomposites.…”