Polymer Photonic Crystal Nanocavity for Precision Strain Sensing

We propose and experimentally demonstrate flexible one-dimensional polymer photonic crystal nanocavities with quality factors exceeding 10⁴ for precision sensing of strain at experimentally measured values of 10^-4. Relying on the cavity's compact structure and polymer's low Young's modulus, the cavity's displacement and the applied force are estimated as 0.94 nm and 55 nN, respectively. This flexible-nanocavity microsensor shows high linearity and repeatability. The microsensor concept is also compatible with liquid environments. The ease of fabrication, flexibility, and biocompatibility of the polymer microsensor promise applications in strain and force measurements at the microscale in the physical, material, and life sciences.