Electrospinner: A review of fiber/yarn and fabric-based piezoresistive sensors: new developments in wearable technology, multifunctional fabrics show potential!

Background

With the rapid development of wearable technology, flexible sensors have greatly improved the comfort, functionality and application potential of electronic devices. Textile-based (fiber, yarn and fabric) piezoresistive sensors have attracted much attention due to their multi-scale material and structural design, flexibility and ability to adapt to complex deformations, as well as simple and reliable signal readout. In recent years, with the rise of material innovation and artificial intelligence technology, fiber, yarn and fabric-based piezoresistive sensors have made significant progress in sensitivity, durability, signal stability and application range, but still face challenges in achieving low cost, high performance and industrial integration.

Recently, Professor Yin Rong's team at North Carolina State University published a research progress titled "Fiber/Yarn and Textile-Based Piezoresistive Pressure Sensors" in Advanced Fiber Materials. This paper systematically summarizes the piezoresistive principle, key performance indicators, conductive and substrate materials, structural design, manufacturing process and multifunctional integration of fiber, yarn and fabric-based piezoresistive sensors. In addition, combined with machine learning algorithms, this paper introduces their cutting-edge applications in the fields of medical health, motion monitoring and human-computer interaction. Finally, this paper discusses in depth the sensor design strategy, the relationship between material-structure-performance, performance evaluation and optimization, as well as industrialization and application potential, and looks forward to the future development direction and opportunities of smart wearable sensing technology.

The main point of this paper

First, the basic theory of piezoresistive effect and its manifestation in textile sensing structures, as well as the key performance indicators in sensor evaluation, are introduced. The pressure response principle of fiber, yarn and fabric-based piezoresistive sensors is the change of interface contact area and the change of the conductive network inside the piezoresistive composite material (as shown in Figure 1). Volume compressibility, porosity (including fiber characteristics, content and distribution), size and concentration of conductive materials and other factors directly affect the piezoresistive performance. Subsequently, a variety of commonly used conductive materials (including inorganic metal materials, organic conductive polymers and carbon nanomaterials) and substrate materials (including artificial and natural polymer materials) for pressure sensing are discussed, and the performance, cost and application requirements of each major material are compared and summarized.

Secondly, the structural design strategies and preparation methods of one-dimensional fiber/yarn morphology and two-dimensional/three-dimensional fabric morphology piezoresistive sensors and their advantages and disadvantages are summarized according to the spatial scale. One-dimensional piezoresistive sensors are mainly core-sheath structures, composed of independent fibers, cross yarns or twisted yarns, which are conducive to high-density array integration. Conductive properties can be obtained through spinning (such as electrospinning, wet spinning, melt spinning, etc.) or physical/chemical modification of insulating fibers/yarns (such as dip coating, in-situ polymerization, electroless plating, etc.). Two-dimensional/three-dimensional fabric piezoresistive sensors usually contain vertical/horizontal coplanar electrodes, piezoresistive layers, and packaging/support materials, which can form a variety of material combinations different from traditional fabric structures to enhance compressibility and sensitivity. For example, the central interlayer is used to provide sufficient deformable space for the upper and lower conductive layers. Fabric conductivity can be obtained by bottom-up (such as solution casting, knitting, embroidery, etc.) or physical or chemical modification of the base fabric (such as physical/chemical vapor deposition, water/solvothermal method, carbonization, etc.)

Thridly, the multifunctional integration of textile structure piezoresistive sensors (such as multimodal detection, signal differentiation, energy/heat/humidity management, etc.) and the intelligent application scenarios of using machine learning to assist health/sports monitoring (such as cardiovascular/respiratory disease diagnosis, posture/gait recognition, etc.) and human-computer interaction (such as interface control, cognitive feedback, etc.) are summarized

Finally, from a broad perspective, the wearable and sensing properties of fibers, yarns and fabric structures are compared with flexible film materials, and the advantages and disadvantages of different textile structures are discussed. This paper summarizes the difficulties, challenges (such as demand trade-offs, material and structure selection, batch costs, industry standards, etc.) and potential solutions of textile-based flexible sensors in engineering technology, product development and evaluation, and looks forward to the future development direction of wearable flexible sensing technology.

Electrospinning Nanofibers Article Source:

https://link.springer.com/article/10.1007/s42765-024-00479-5