Study Of Flexible Pressure Distribution Sensor Based On All-in-One-Shaped Honeycomb Woven Fabric

In recent years,textiles have continued to innovate,showing great application potential.The textile sensing material that collects environmental signals is an important smart textile,which has attracted much attention.In addition to sensing functions,they also exhibit characteristics such as light weight,low modulus,high elasticity,and skin-friendliness,presenting unique advantages in the fields of health monitoring,smart medical care,rehabilitation training and smart elderly care.However,textile-based flexible sensing materials still have problems such as low sensitivity,poor mechanical properties,and low repeatability stability.Therefore,research on textile sensing materials with high sensitivity,high strength,stable and reliable signal,and integral molding has become an important direction.Honeycomb woven fabric is a single-layer woven fabric with three-dimensional effect,as well as an excellent carrier for constructing flexible mechanical sensing materials.In this paper,firstly,we studied the structural characteristics and formation mechanism of honeycomb fabric.A pressure distribution sensor based on the principle of capacitive array was prepared by arranging the position sequence of conductive and non-conductive yarns in the honeycomb tissue.The yarns(including conductive carbon fiber)and the fabric morphology were characterized.Secondly,the physical properties of the designed honeycomb fabric were tested and compared,including air permeability,warmth retention,water absorption,moisture permeability,bending resistance,compression and stretchability.Then,the capacitive pressure sensor model was constructed according to the unique 3D structure of the honeycomb fabric,and the mathematical formula was used to analyze the working principle of the honeycomb fabric sensor.The characteristic parameters of the developed sensor were studied,including sensitivity,linearity,measurement range and repeatability.Finally,the self-designed software and hardware signal acquisition system was used to test the capacitance change of the interweaving point of the sensing fabric under different pressures and the pressure distribution change based on the capacitance array.Meanwhile,the fabric sensor was used for application testing and analysis in different application environments.The experimental results showed that the floating length of the yarn in the honeycomb tissue unit increased or decreased at the same time,forming a three-dimensional structure of a two-sided inverted pyramid and a tetrahedron in the internal space.The three-dimensional effect was more obvious when elastic yarns were used.Also,the increased density resulted in a tighter fabric structure,greater thickness and weight.Both the elastic yarns and carbon fiber bundles raised the weight of the fabric,which had a great effect on the basic physical characteristics and morphology of as-made honeycomb woven fabrics.For comfort performance,it was found that air permeability and vapor transmission decrease,while the warmth retention and water absorption grew due to the use of elastic yarns and increased weft density.In terms of mechanical properties,elastic yarns reduced the compressional sensitivity of fabric owing to the increased thickness.Thus,the bending length and breaking elongation became larger as the fabric density increased.Elastic honeycomb weaves had higher warp strength than non-elastic weaves,which could be stretched about 5-10 times longer than its original length in the weft direction due to the used elastic yarns and honeycomb 3D structure.Furthermore,the developed sensor achieved outstanding performance with a GF of 0.045k Pa^-1 under 10 k Pa,as well as low hysteresis,fast response time,good durability and stability.By testing the single-interleaved capacitance changes under different pressures,it was proved that the sensor could detect pressure scenarios in various applications,such as finger pressing,object placement and handshake.Also,the honeycomb fabric could construct a capacitor array structure to test the pressure distribution under compression of objects of different weights,and the peak capacitance increased with the increase of weight,which could successfully monitor the pressure distribution under various loading conditions.The honeycomb fabric pressure sensor has simple preparation technology,integrated molding,low cost,stable signal output,excellent performance,and easy industrialization.Therefore,it shows great application prospects in the fields of health monitoring,medical equipment,human-machine interface and electronic skin in the future.