Multifunctional Ti₃C₂T_x MXene/Poly(Styrene‐Methacrylic Acid)@Polypyrrole Nanospheres/Thermoplastic Polyurethane Electrospinning Membrane for High Sensitivity Pressure Sensing and Pressure‐Electrothermal

Abstract

wearable electronics and are classified into four categories according to their sensing mechanisms: piezoresistive, capacitive, piezoelectric, and triboelectric. [6][7][8][9] Compared to the other pressure sensors, the piezoresistive pressure sensor constructed from flexible substrates and conductive materials is considered the most promising for industrialization. [10] This benefit from the fact that the piezoresistive pressure sensor has the advantages of reliable sensing performance, low costs, less susceptibility to external environmental interference, and relatively low energy consumption. [11] Much progress has been made in previous research into the piezoresistive pressure sensor, and much of these works have been aimed at improving the sensitivity, sensing range, and stability of the sensor. [12] Particularly in the area of human movement and physiological monitoring, highly sensitive pressure sensors enable continuous monitoring of health states by acquiring the body's vital signals in real time, which is essential for future personalized medicine and diagnosis. [13] To enhance the sensitivity of pressure sensor, the introduction of superior conductive materials on flexible substrates with surface-built microstructures has proven to be an effective strategy. [14] This is because the construction of various microstructures or nanostructured geometries in flexible substrates can increase the degree of change in their contact resistance under pressure loading, thereby improving the sensitivity of pressure sensors. [15] Micro-pyramidal structures, micro-pillar structures, micro-hemispheric structures, micro-cone arrays, and hollow sphere microstructures have been published in previous research works, and these pressure sensors show high sensitivity. [16] Park et al. [17] have constructed micro-hemispheres, micro-pyramids, and micro-cylinders on the surface of polydimethylsiloxane(PDMS), and then deposited carbon nanotubes (CNT) to prepare compressible conductive CNT/PDMS films. The finite element theoretical model is used to analyze the contrast sensitivity, and it is found that the tunnel resistance can be greatly reduced due to the maximum change of contact area of the interlocking array based on micro-hemispherical structure under the same The introduction of superior conductive materials on flexible substrates with surface-built microstructures has proven to be an effective solution for enhancing the sensitivity of pressure sensor. Thermoplastic polyurethane electrospun membrane (TPUEM) with multi-void structure is used as substrate, and poly(styrene-methacrylic acid)@polypyrrole nanospheres (PPNs) are pumped into the TPUEM by vacuum filtration to form a microstructure on the surface of thermoplastic polyurethane (TPU) electrospun fibers. The MXene dispersion is sprayed on the surface of PPNs/TPUEM. As it is gradually infiltrated into the material, a conductive network is formed. When the MXene/PPNs/TPUEM is subjected to pressure, its resistance decreases significantly due to the close contact between MX...

Review—Electrostatic Spinning for Manufacturing Sensitive Layers of Flexible Sensors and Their Structural Design

“…32 The vast majority of current electrostatic spinning technologies are used to fabricate flexible substrates for sensitive layers in flexible sensors. After electrospinning the substrate material into a nanofiber film, the active conductive filler is then doped onto the flexible substrate by in situ polymerization, [33][34][35] vacuum evaporation, 36 sputtering, [37][38][39][40] chemical deposition, extraction, 36,41,42 electrostatic spraying, 43 and dip coating [44][45][46][47][48][49] to form a composite nanofiber film with conductive activity. Structural properties of flexible substrates provide high sensitivity of such composite nanofiber membrane.…”

“…It was shown that PANI fibers doped with hydrochloric acid were able to produce high electrical conductivity of about 20 S cm −1 and exhibited 10ppm detection sensitivity to ammonia. Cheng et al 42 enhanced the degree of contact resistance variation of the sensor under pressure loading by building nanoscale geometric microstructures on a flexible substrate in order to make further breakthroughs in the sensitivity of flexible pressure sensors. The main design idea was to pump PPy nanomicrospheres onto a thermoplastic polyurethane electrospun membrane by decompression pumping to form an octopus tentacle-like nanostructure, and then spray on MXene dispersion to construct a multilayer conductive network with nanosphere structure (Figs.…”

Recent progress in flexible micro-pressure sensors for wearable health monitoring

“…Flexible piezoresistive micro-pressure sensors have promising applicable potential because of their simple structure, facile materials preparation, low cost, and other merits. [125][126][127] Graphene, carbon nanobers and carbon nanotubes (CNTs) are the most common conductive materials for preparing piezoresistive pressure sensors. 128 These sensors have high sensitivity, great stretchability, good exibility, and excellent stability, and are suitable for micro-pressure detection in different application scenarios.…”

Highly Stretchable, Highly Sensitive, and Antibacterial Electrospun Nanofiber Strain Sensors with Low Detection Limit and Stable CNT/MXene/CNT Sandwich Conductive Layers for Human Motion Detection

“…With the rapid rise in wearable electronic devices, flexible sensors are growing by leaps and bounds and are showing substantial applications in various fields, such as human motion monitoring, − artificial intelligence robotics, − and human–computer interaction. − Crack-structured strain sensors with conductive materials coated on a flexible substrate have become a widely used strategy ,, with advantages such as easy fabrication and short response time. However, it is still a challenge to combine high sensitivity and high tensile range due to the resistance change of crack-based sensors based on the breakage and reversion of the conductive network. , High sensitivity requires the sensor to undergo violent fracture or recovery of the conductive network at a weak stretch, which makes it impossible to maintain the conductive network at large strains .…”