Flow cytometer system for single-shot biosensing based on whispering gallery modes of fluorescent microspheres

Fluorescent and lasing whispering gallery mode microresonators for sensing applications

“…Microspherical liquid‐drop resonators have resurfaced as candidates for microlasers and biosensors , despite initial limitations preventing their widespread usage . Liquid droplets form naturally smooth spherical surfaces due to surface tension, allowing high Q‐factors to be realized (e.g.…”

“…Finally, fluorescent microresonators offer the potential for in‐vivo sensing. After the first demonstration of intracellular sensing and tagging , the concept of free‐floating resonators inside blood vessels no longer seems quite as unrealistic, especially with the emergence of flow cytometry . However, for this vision to be realized one would have to use a gain medium in the NIR rather than in the visible spectrum , as the latter is strongly absorbed by tissue.…”

Whispering gallery mode resonators in continuous flow: spectral assignments and sensing with monodisperse microspheres

“…Consequently, this means that even lower quality data that have only a few observable WGMs or spectra that have contributions from more than one microsphere can still be leveraged to obtain useful information. In contrast, these features are likely to prevent analogous area matching algorithms 7,8,16 from performing well. Additionally, the ability to obtain information from spectra which arise from multiple WGMRs allows one to use a wide range of microsphere concentrations which is attractive for studying real world samples.…”

“…Perhaps most similar to the efforts described herein, Allen and co-workers have developed a reference-free analysis scheme for WGM spectra collected in free flowing solution 7,8 or alongside a flow cytometry setup. 16 In their analysis scheme, the entirety of the observed WGM spectral profile over a fixed wavelength region is compared to predicted spectra obtained from Chew's formalism of Mie theory. 17,18 The technique described therein was successful both at identifying the refractive indices of various alcohol solutions and discriminating between biological analyte absorption and changes to the homogenous refractive index.…”

Whispering Gallery Mode Devices for Sensing and Biosensing

“…On the other hand, fluorescent microspheres doped with different gain media and therefore emitting in different wavelength regions would be easier to implement for multiplexed sensing. In a similar spirit, multiple fluorescent microspheres have been used for flow cytometry, in which a simple algorithm based on the Chew model may permit the concurrent determination of individual microsphere radius and refractive index [81,153]. While the full demonstration of this approach remains open, it presents a promising application of fluorescent microspheres.…”