چكيده انگليسي :
During the past few decades, the world has witnessed the stunning development of flexible pressure sensors in various fields. Wearable pressure sensors convert external stimuli into electrical signals. Capacitive pressure sensors (CPS) have attracted widespread attention due to their stability, low power consumption, high response speed, high sensitivity, simple structure, and low-cost manufacturing process. In this research, cotton fabric coated with silver nanoparticles and polyaniline was used separately and in combination to make the capacitive pressure sensor electrode layer. For this purpose, the same amount of silver nitrate was used in two electroless methods, but in the second method, ammonia and ethylene diamine were used as complexing agents, and the properties of complexing agents were investigated in this method. Also, in-situ polymerization of polyaniline was performed in different cycles, and the coating and penetration of polyaniline polymer on the fabric surface was investigated, and in another example, the combination of polyaniline and silver nanoparticles was used. The coated samples as the electrode layer of the capacitive pressure sensor were placed as parallel plates on the top and bottom of the spacer layer and the performance of the sensor was investigated at different pressures. In this research, the characteristics of the coated electrode layer were investigated and tests such as SEM, FTIR, XRD, EDX, washing stability, wettability, surface resistance, strength and changes in thickness and weight were performed. In the SEM images, the continuous and uniform coating of silver nanoparticles was shown in the electroless method. The coating and interconnection of silver nanoparticles results in a conductive fabric, for this reason, the surface resistance of the coated fabric using the second electroless method was found to have the lowest surface resistance value (51 /squar). In FTIR analysis, the characteristic bands of the conductive form of polyaniline and silver nanoparticles were observed. In EDX analysis, the weight percentage of the elements in different samples was checked and it was observed that the sample coated with the second electroless method has the highest weight percentage of silver element (92%) compared to other samples, and in the sample coated with polyaniline and Silver, nitrogen and sulfur elements were present due to the imine and amine groups that represent the conductive form of polyaniline. In the XRD analysis, it was observed that in the samples coated with silver nanoparticles, in addition to the characteristic peaks of cotton fabric, there were peaks at angles of 38.18, 44.34, 64.54, and 77.46 degrees, which indicated the coating of silver nanoparticles. In this research, it was observed that the washing stability of silver nanoparticles with electroless methods is excellent after three washing cycles. Also, the strength properties of the samples coated with electroless methods increased compared to the raw sample. While in the polymerization in place of polyaniline due to the use of dilute acid, the cotton fabric was slightly destroyed and its strength properties decreased. In this research, the performance of the pressure sensor was evaluated in the range of high pressures of 1000, 1500, 2000 KPa at different speeds of 10, 30, 60 mm/min. In the investigation of the performance of the pressure sensor, the appropriate method of silver nanoparticle coating, i.e. second electroless, was obtained for use in the capacitive pressure sensor electrode. record movement signals of athletes and robotics.
