Stretching the Limits of Refractometric Sensing in Water Using Whispering-Gallery-Mode Resonators
A novel application of microresonators for refractometric sensing in aqueous media is presented. To carry out this approach, microspheres of different materials and sizes were fabricated and doped with Nd<sup>3+</sup> ions. Under 532 nm excitation, the microspheres presented typical NIR...
Saved in:
| Main Authors: | , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-01-01
|
| Series: | Chemosensors |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2227-9040/13/2/33 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1849720203171069952 |
|---|---|
| author | Kevin Soler-Carracedo Antonia Ruiz Susana Ríos Sergio de Armas-Rillo Leopoldo L. Martín Martin Hohmann Inocencio R. Martín Fernando Lahoz |
| author_facet | Kevin Soler-Carracedo Antonia Ruiz Susana Ríos Sergio de Armas-Rillo Leopoldo L. Martín Martin Hohmann Inocencio R. Martín Fernando Lahoz |
| author_sort | Kevin Soler-Carracedo |
| collection | DOAJ |
| description | A novel application of microresonators for refractometric sensing in aqueous media is presented. To carry out this approach, microspheres of different materials and sizes were fabricated and doped with Nd<sup>3+</sup> ions. Under 532 nm excitation, the microspheres presented typical NIR Nd<sup>3+</sup> emission bands with superimposed sharp peaks, related to the Whispering Gallery Modes (WGMs), due to the geometry of the microspheres. When the microspheres were submerged in water with increasing concentrations of glycerol, spectral shifts for the WGMs were observed as a function of the glycerol concentration. These spectral shifts were studied and calibrated for three different microspheres and validated with the theoretical shifts, obtained by solving the Helmholtz equations for the electromagnetic field, considering the geometry of the system, and also by calculating the extinction cross-section. WGM shifts strongly depend on the diameter of the microspheres and their refractive index (RI) difference compared with the external medium, and are greater for decreasing values of the diameter and lower values of RI difference. Experimental sensitivities ranging from 2.18 to 113.36 nm/RIU (refractive index unit) were obtained for different microspheres. Furthermore, reproducibility measurements were carried out, leading to a repeatability of 2.3 pm and a limit of detection of 5 × 10<sup>−4</sup> RIU. The proposed sensors, taking advantage of confocal microscopy for excitation and detection, offer a robust, reliable, and contactless alternative for environmental water analysis. |
| format | Article |
| id | doaj-art-b78ccd079e9e41f3a6c633a93fb7181d |
| institution | DOAJ |
| issn | 2227-9040 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Chemosensors |
| spelling | doaj-art-b78ccd079e9e41f3a6c633a93fb7181d2025-08-20T03:11:59ZengMDPI AGChemosensors2227-90402025-01-011323310.3390/chemosensors13020033Stretching the Limits of Refractometric Sensing in Water Using Whispering-Gallery-Mode ResonatorsKevin Soler-Carracedo0Antonia Ruiz1Susana Ríos2Sergio de Armas-Rillo3Leopoldo L. Martín4Martin Hohmann5Inocencio R. Martín6Fernando Lahoz7Faculty of Chemistry, Adam Mickiewicz University, Uniwersytetu Poznańskiego 8, 61-614 Poznań, PolandDepartamento de Física, Universidad de La Laguna, Apdo. 456, E-38200 San Cristóbal de La Laguna, SpainDepartamento de Física, Universidad de La Laguna, Apdo. 456, E-38200 San Cristóbal de La Laguna, SpainDepartamento de Física, Universidad de La Laguna, Apdo. 456, E-38200 San Cristóbal de La Laguna, SpainDepartamento de Física, Universidad de La Laguna, Apdo. 456, E-38200 San Cristóbal de La Laguna, SpainInstitute of Photonic Technologies (LPT), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Konrad-Zuse-Straße 3/5, 91052 Erlangen, GermanyDepartamento de Física, Universidad de La Laguna, Apdo. 456, E-38200 San Cristóbal de La Laguna, SpainDepartamento de Física, Universidad de La Laguna, Apdo. 456, E-38200 San Cristóbal de La Laguna, SpainA novel application of microresonators for refractometric sensing in aqueous media is presented. To carry out this approach, microspheres of different materials and sizes were fabricated and doped with Nd<sup>3+</sup> ions. Under 532 nm excitation, the microspheres presented typical NIR Nd<sup>3+</sup> emission bands with superimposed sharp peaks, related to the Whispering Gallery Modes (WGMs), due to the geometry of the microspheres. When the microspheres were submerged in water with increasing concentrations of glycerol, spectral shifts for the WGMs were observed as a function of the glycerol concentration. These spectral shifts were studied and calibrated for three different microspheres and validated with the theoretical shifts, obtained by solving the Helmholtz equations for the electromagnetic field, considering the geometry of the system, and also by calculating the extinction cross-section. WGM shifts strongly depend on the diameter of the microspheres and their refractive index (RI) difference compared with the external medium, and are greater for decreasing values of the diameter and lower values of RI difference. Experimental sensitivities ranging from 2.18 to 113.36 nm/RIU (refractive index unit) were obtained for different microspheres. Furthermore, reproducibility measurements were carried out, leading to a repeatability of 2.3 pm and a limit of detection of 5 × 10<sup>−4</sup> RIU. The proposed sensors, taking advantage of confocal microscopy for excitation and detection, offer a robust, reliable, and contactless alternative for environmental water analysis.https://www.mdpi.com/2227-9040/13/2/33lanthanidesoptofluidicsoptical resonatorsWGMrefractive index sensormicrospheres |
| spellingShingle | Kevin Soler-Carracedo Antonia Ruiz Susana Ríos Sergio de Armas-Rillo Leopoldo L. Martín Martin Hohmann Inocencio R. Martín Fernando Lahoz Stretching the Limits of Refractometric Sensing in Water Using Whispering-Gallery-Mode Resonators Chemosensors lanthanides optofluidics optical resonators WGM refractive index sensor microspheres |
| title | Stretching the Limits of Refractometric Sensing in Water Using Whispering-Gallery-Mode Resonators |
| title_full | Stretching the Limits of Refractometric Sensing in Water Using Whispering-Gallery-Mode Resonators |
| title_fullStr | Stretching the Limits of Refractometric Sensing in Water Using Whispering-Gallery-Mode Resonators |
| title_full_unstemmed | Stretching the Limits of Refractometric Sensing in Water Using Whispering-Gallery-Mode Resonators |
| title_short | Stretching the Limits of Refractometric Sensing in Water Using Whispering-Gallery-Mode Resonators |
| title_sort | stretching the limits of refractometric sensing in water using whispering gallery mode resonators |
| topic | lanthanides optofluidics optical resonators WGM refractive index sensor microspheres |
| url | https://www.mdpi.com/2227-9040/13/2/33 |
| work_keys_str_mv | AT kevinsolercarracedo stretchingthelimitsofrefractometricsensinginwaterusingwhisperinggallerymoderesonators AT antoniaruiz stretchingthelimitsofrefractometricsensinginwaterusingwhisperinggallerymoderesonators AT susanarios stretchingthelimitsofrefractometricsensinginwaterusingwhisperinggallerymoderesonators AT sergiodearmasrillo stretchingthelimitsofrefractometricsensinginwaterusingwhisperinggallerymoderesonators AT leopoldolmartin stretchingthelimitsofrefractometricsensinginwaterusingwhisperinggallerymoderesonators AT martinhohmann stretchingthelimitsofrefractometricsensinginwaterusingwhisperinggallerymoderesonators AT inocenciormartin stretchingthelimitsofrefractometricsensinginwaterusingwhisperinggallerymoderesonators AT fernandolahoz stretchingthelimitsofrefractometricsensinginwaterusingwhisperinggallerymoderesonators |