Validation of photocurrent-based strain sensing using a P3HT-based nanocomposite

There is a dire need to develop novel robust and reliable sensing technologies for identifying the onset of structural damage and for preventing sudden catastrophic structure failures. While numerous sensors (e. g., fiber optics, wireless sensors, piezoelectrics, and remote sensing, among others) have been proposed for structural health monitoring, the current generation of sensing systems suffer from some fundamental limitations such as discrete sensing and high energy demand. In this study, a new paradigm for strain sensing and structural monitoring is proposed by developing a novel optoelectronic nanocomposite that can generate strain-sensitive photocurrent. Unlike other common sensing transducers, the proposed nanocomposite sensor is a self-sensing material, is conformable to structural surfaces, is of small form factor, and does not require an external power source. First, regioregular poly(3-hexylthiophene) (P3HT) conductive polymer (i.e., the main photoactive component of the nanocomposite) is synthesized in the laboratory and characterized via nuclear magnetic resonance (NMR). Second, thin films comprising of P3HT and carbon nanotubes are fabricated via spin coating. Upon specimen fabrication, the nanocomposite's photocurrent generation capabilities are investigated and evaluated. Finally, thin film specimens are loaded in an electromechanical load frame, and the preliminary results show that the magnitude of generated photocurrent varies in tandem with applied tensile strains.