https://doi.org/10.1051/epjap/2025030
Original Article
Integrated resonant structure for colloidal dispersion stability: development of a resonant optical zetameter
1
Univ Rennes, CNRS, IETR - UMR 6164, F-35000 Rennes, France
2
Univ Rennes, CNRS, ISCR - UMR 6226, F-35000 Rennes, France
3
Univ Rennes, CNRS, IPR - UMR 6251, F-35000 Rennes, France
4
Univ Rennes, UAR 2025 ScanMAT, F-35000 Rennes, France
5
Centrale/Supelec, Campus de Rennes, F-35510 Cesson-Sévigné, France
* e-mail: jordan.gastebois@univ-rennes.fr
** e-mail: bruno.beche@univ-rennes.fr
Received:
22
May
2025
Accepted:
18
November
2025
Published online: 23 December 2025
Long-term storage of colloidal solutions presents significant challenges in maintaining the physical and mechanical properties of manufactured products over extended periods. Ensuring stability is critical for agro-alimentary products, pharmaceutical formulations, and petroleum applications to preserve product quality and longevity during storage. Monitoring the stability of colloidal dispersions is essential for anticipating potential degradation over time. This study explores the evaluation of stability criteria using quasi-surface resonant analysis. Specifically, the zeta potential of colloidal solutions is investigated via resonant optical parameter, the Free Spectral Range (FSR), to distinguish between stable and unstable dispersions. For this purpose, sensors based on organic UV210 Micro-Resonators (MRs) were fabricated using deep UV photolithography. These MRs were integrated into an optical test platform, enabling real-time data collection with a spectrometer and dedicated MATLAB processing. The study focuses on black carbon nano powders dispersed in water and in water plus an anionic surfactant (Sodium Dodecyl Sulfate, SDS). The findings show that unstable solutions exhibit an increasing FSR over time, which is indicative of sedimentation, whereas stable dispersions maintain a constant FSR. These results are validated through complementary rheological and zeta potential measurements, establishing a clear correlation between FSR variations and colloidal dispersion stability. This study demonstrates the potential of resonant optical measurements as a novel tool for assessing colloidal dispersion stability, functioning as a “zetameter” on a surfacic platform.
Key words: Colloidal dispersion / dark solution stability / integrated photonics and resonators / zeta potential
© J. Gastebois et al., Published by EDP Sciences, 2025
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
