Preparation Of Stretchable Ecoflex Conductive Fiber And Research In Color Change Sensing

Fibrous flexible sensors are widely used in monitoring human motion because of their strong integration and excellent wearing comfort.However,due to the limitation of tensile properties,the traditional fiber sensor has the defects of narrow monitoring deformation range and low sensitivity.Compared with other elastic materials,Ecoflex has a very high tensile strain capacity(about 980%)and a low Young’s modulus(about 183.4 k Pa),which has a natural material advantage to overcome this problem and can be used to replace the traditional elastic substrate to enhance the tensile performance of flexible fiber sensors.However,the resistance of Ecoflex itself is too great to be sensed,and the synthesis process and chemical properties of Ecoflex are not suitable for common spinning methods.Therefore,it is still very challenging to realize the large-scale production of Ecoflex fiber and apply it to wearable fiber sensors.In addition,the stretchable fiber sensor can’t detect the path of human motion because it doesn’t have optical signal response,which greatly limits its application in motion capture.In order to solve the above problems,a new thermochromic Ti @ Ecoflex/CB fiber sensor with ultra-high tensile capacity was prepared by improving wet spinning technology.The specific research contents and conclusions are as follows:(1)The influence of different spinning processes on the structure,i.e.mechanical properties,of Ecoflex fibers was investigated.In order to get better spinning effect,the prepolymerization time of Ecoflex is controlled at 35℃ for about 15 minutes.The elongation of Ecoflex fiber was optimized by changing spinning speed and coagulation bath temperature.The results showed that the elongation at break of Ecoflex fiber prepared at 10 ml/h and 60℃was 660.00 42.6%,and the breaking strength was 15.68±2.35 Mpa,which had good mechanical properties.(2)By studying the sensing mechanism of Ecoflex/CB flexible fiber sensor,the doping amount of carbon black is controlled to increase the conductivity of the material.According to the mechanical properties,electrical properties and sensitivity,the doping amount of carbon black is selected.The results show that the 7.5wt.%Ecoflex/CB flexible fiber sensor prepared by the optimized process shows a wide sensing range of up to 200%,high sensitivity with a strain coefficient of 37 in the strain range of 0-100%,and a fast response time of about 43 ms.Ecoflex/CB sensor also shows insensitivity to bending,twisting and pressure,and has water washing resistance and temperature stability.(3)In order to combine the 3D optical motion capture system of computer color recognition with the stretchable sensor,TI@Ecoflex/CB fiber was prepared by coating a colorchanging layer,which endowed the stretchable sensor with the function of real-time color change.And a wide color range from pink to blue to purple in a gradient range of 20-30 DEG C..The color-changing sensing performance remains basically unchanged after 3000 stretching(50%)cycles.By integrating the optical motion capture system with the fabric sensor based on thermochromic fiber filaments,so as to detect the three-dimensional path of human motion in real time.This work provides a new way to develop a stretchable color-changing strain sensor that can track the three-dimensional space-time motion of human body.