Conducting Polymer Coated Carbon Fiber Composites for Enhanced Strain Sensing Applications

Abstract

In modern applications, such as robotics, wearable, and healthcare, strain sensors are crucial as it is possible to accurately measure mechanical defects. The objective of this research was to improve strain sensing of carbon fiber (CF)-based materials by using surface modifications and conducting polymer (CP) coating. Sulfuric acid and nitric acid were used by the ratio of 3 to 1, to etched carbon fiber (e-CF) by making the surface rougher and having more functional groups to improve adhesion to the polymer. Composites consisted of CF coated with polyaniline (PANI) were synthesized through in-situ polymerization and then coated with Poly(3,4-Ethylenedioxythiophene): Polystyrene Sulfonate (PEDOT:PSS) to give composites based on conducting polymers. The structural, chemical and thermal characterization of the synthesized composites was done using X ray diffraction, Fourier-transform infrared spectroscopy, and thermogravimetric analysis. Electrical conductivity and strain-sensing capability were assessed during several forms of bending, including finger, wrist, and elbow motions. The sample with PEDOT:PSS coated on top of PANI coated e-CF showed the highest sensitivity, as well as superior thermal stability and electrical conductivity, compared to the other composites. This study demonstrates that changing the surface and coating with two different types of CP can significantly enhance the overall characteristics and performance of CF-based composites. These findings indicate a potential interest in employing CP coated CF composites as high performance strain sensors in healthcare, wearable electronics, robotics, and smart textiles as well.