Whispering-Gallery Sensors

Abstract

Summary Optical whispering-gallery mode (WGM) microresonators, confining resonant photons in a microscale volume for long periods of time, strongly enhance light-matter interactions, making them an ideal platform for photonic sensors. One of the features of WGM sensors is their capability to respond to environmental perturbations that influence the optical mode distribution. The exceptional sensitivity of WGM devices, coupled with the diversity in their structures and the ease of integration with existing infrastructures, such as conventional chip-based technologies, has catalyzed the development of WGM sensors for a broad range of analytes. WGM sensors have been developed for multiplexed detection of clinically relevant biomolecules while also being adapted for the analysis of single-protein interactions. They have been used for the detection of materials in different phases and forms, including gases, liquids, and chemicals. Furthermore, WGM sensors have been used for a wide variety of field-based sensing applications, including electric field, magnetic field, force, pressure, and temperature. WGM sensors hold great potential for applications in life and environmental sciences. They are expected to meet the ever-increasing demand in sensor networks, the Internet of Things, and real-time health monitoring. Here we review the mechanisms, structures, parameters, and recent advances of WGM microsensors and discuss the future of this exciting research field.

Emerging Options for the Diagnosis of Bacterial Infections and the Characterization of Antimicrobial Resistance

“…The surfaces of the micro-resonators can be functionalized with highly specific capture molecules for use in bioanalytical applications [ 89 , 90 ]. WGM sensors exhibit outstanding sensitivity and permit label-free detection at the level of single molecules or atoms in a very short timeframe [ 91 , 92 ].…”

“…In addition to high sensitivity and short turnaround time, low manufacturing costs and the capacity to generate results from small sample volumes are additional favorable features of this technology that will facilitate its integration into clinically relevant settings [ 92 ]. Nonetheless, the transformation from the laboratory to a clinical diagnostic environment remains a major challenge and will require innovative solutions, especially with respect to sensor stability and specificity [ 91 ].…”

Pulling the Brakes on Fast and Furious Multiple Drug-Resistant (MDR) Bacteria

“…Their sensitivity, together with the diversity of structures, leads to the development of these devices for a wide range of analytes. These are being used for detecting clinically relevant biomolecules as well as single-protein interactions [ 215 ]. Thus, this technique is proven to be faster and potentially sensitive.…”

“…Optical (bio)sensors facilitate us by monitoring polarization, intensity, phase, speed, and frequency of light. Whispering gallery mode (WGM) microresonators are at the forefront for over the last two decades [ 216 ]. They provide a label-free optical method to detect bacteria rapidly with high sensitivity [ 217 ].…”

Optical whispering-gallery mode barcodes for high-precision and wide-range temperature measurements

“…In addition, the high-quality factor (Q-factor) of a resonator leads to a narrow bandwidth in the spectrum, making it easier to resolve subtle changes when tracking the resonant wavelengths, which consequently improves the detection limit 37,41 . Among various kinds of optical resonator sensors, whispering-gallery mode (WGM) resonators have attracted increasing attention due to their exceptionally high-quality factors [42][43][44] . Various WGM resonators have been demonstrated to measure the temperature in both laboratory and outdoor environments by tracking the changes in the resonant wavelength [45][46][47][48][49] because the temperature dependence of the resonance arises from thermally induced changes in the refractive index and in the physical dimensions of the resonator.…”