Strain sensing using photocurrent generated by photoactive P3HT-based nanocomposites

Many sensor technologies commonly used for structural health monitoring (SHM) still suffer from high energy demand, large form factors and weight, and indirect damage detection. These constraints limit the application of these sensor systems for SHM of various space, aeronautical, mechanical and civil structures. In this study, a self-sensing thin film fabricated from poly(3-hexylthiophene) (P3HT) and multi-walled carbon nanotubes (MWNTs) is proposed for strain sensing. Unique to this nanocomposite is its ability to generate a photocurrent in response to light illumination, and it will be shown that the magnitude of the generated photocurrent scales with the level of applied strain. First, two types of P3HT-based sample sets with and without MWNTs have been prepared by spin coating. Second, current?voltage measurements have been used for characterizing electrode response due to applied strains. Lastly, strain sensing characterization tests have been conducted, where thin film generated photocurrent has been measured during applied cyclic tensile strains. The nanocomposites? strain sensitivity, linearity and sensing range have been analyzed and compared. The results show that these P3HT-based thin films can be used for photocurrent-based strain sensing. These films do not require an external power source, have small form factors and can directly measure structural strains.