Séminaire Qilin Zhou

Lanthanide-Doped Luminescent Nanorods as Optical Probes for Measuring Flow-Induced Shear and Mechanical Strain

Dr. Qilin Zou, Laboratory for Vascular Translational Science (LVTS), INSERM, Université Sorbonne Paris Nord (Paris 13), Université Paris Cité

Abstract

Mechanical forces and deformations play a fundamental role in biological systems, soft materials, and engineering applications. However, their local measurement remains challenging, particularly in complex fluids and deformable materials. In this seminar, I will present our recent work on developing lanthanide-doped luminescent nanorods as versatile optical probes for quantitative mechanical sensing. By regulating the anisotropic morphology and tailoring the polarized luminescence of Eu³⁺-doped LaPO₄ nanorods, we establish an optical sensing approach that translates nanorod collective orientation into a measurable signal, enabling the reliable and accurate measurement of local mechanical environments.

I will first introduce our shearmetry strategy, in which flow-induced alignment of luminescent nanorods provides an optical readout of local shear stress. Through the development of size-controlled LaPO₄:Eu³⁺ nanorods, we demonstrate how nanoparticle morphology, particularly nanorod aspect ratio (length/width), governs their orientational dynamics and sensing performance. Combined with the tunable rheological properties of nanorod-based fluids, this approach enables quantitative mapping of shear-stress distributions in microfluidic channels, including complex dynamic flows and non-Newtonian fluids that mimic physiological biofluids. Furthermore, I will explore the extension of polarized luminescence sensing from fluid mechanics to solid-state deformation. By incorporating LaPO₄:Eu³⁺ nanorods into flexible polydimethylsiloxane (PDMS) matrices, we demonstrate reversible optical strain sensing based on deformation-induced nanorod alignment. The resulting changes in polarized Eu³⁺ emission provide a quantitative measure of applied strain, while controlling nanorod concentration and aspect ratio offers a means of tailoring sensor sensitivity and operating range. In summary, these studies establish lanthanide-based polarization luminescence as a versatile optical platform for probing mechanical forces across fluid and solid environments. By combining nanomaterial engineering, lanthanide photophysics, and mechanical sensing, this strategy opens new opportunities for spatially resolved mechanical determination, with potential applications in biofluidics, soft robotics, and wearable sensing technologies.