Reversible Strain Sensing via Lanthanide-Doped Luminescent Nanorods in Flexible Polymers

Flexible strain sensors are emerging with widespread applications including soft robotics, human heath monitoring, and wearable devices. However, the arduous fabrication process and complicated operation of current sensors limit their practical applications. In this study, we present a simple and effective approach for strain sensing based on optical polarization of lanthanide-doped luminescent nanorods. Specifically, LaPO 4 nanorods doped with trivalent europium (Eu 3+ ) are embedded into an elastic polydimethylsiloxane matrix to form the sensor. The alignment of nanorods along the direction of stretching leads to a measurable change in optical polarization of the luminescence of Eu 3+ . By analyzing the orientational order parameter of the nanorods, the locally applied strain can be quantitatively determined. We have investigated systematically the influence of nanorods’ concentration and aspect ratio on sensor performance, which enables tunable working range and sensitivity for diverse application needs. This approach offers an innovative strategy for the development of next-generation optomechanical sensors. • Developed an optical strain sensor using nanorods embedded flexible film. • Introduced lanthanide polarized emission to quantify nanorod alignment and strain. • Tunable sensor performance by adjusting nanorod aspect ratio and concentration. • Demonstrated optomechanical sensing toward soft robotics and wearable devices.