Microwave dielectric sensing of free-flowing, single, living cells in aqueous suspension
File(s)
Accepted version
Author(s)
Type
Journal Article
Abstract
Dielectric measurements offer the possibility of highly sensitive detection of physical cell properties, and are of interest for clinical applications due to their non-destructive nature and the lack of need for cell labelling. Here we report sensitive measurements on single, living, free-flowing cells (not electrostatically or dielectrophoretically trapped, cultured or fixed directly on sensing elements) in aqueous medium at ~9.8 GHz taken using a coupled dielectric-split ring resonator assembly. Inductive coupling between the two resonators enabled separation of microfluidic chips from RF connectors and allowed for time-resolved continuous-wave measurements on flowing single cells via the coaxial ports of a dielectric-loaded microwave cavity. Analysis via an equivalent circuit model showed that the novel resonator assembly maintained the permittivity-dependent sensitivity of a split ring resonator while operating at quality factors >1000 with lossy aqueous media (typically ~1900). Using a microfluidic channel with a 300 x 300 μm cross section, at a water-loaded resonant amplitude of ~-22 dB at 0 dBm input power level, shifts in amplitude due to individual cells passing through the sensing region of up to -0.0015 dB were observed. Correlations between averaged amplitude shifts and cell size as well as material properties demonstrate the diagnostic potential of this technique.
Date Issued
2020-06
Date Acceptance
2019-07-15
Citation
IEEE Journal of Electromagnetics, RF and Microwaves in Medicine and Biology, 2020, 4 (2), pp.97-208
ISSN
2469-7249
Publisher
Institute of Electrical and Electronics Engineers (IEEE)
Start Page
97
End Page
208
Journal / Book Title
IEEE Journal of Electromagnetics, RF and Microwaves in Medicine and Biology
Volume
4
Issue
2
Copyright Statement
© 2019 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information
Sponsor
Engineering & Physical Science Research Council (EPSRC)
Identifier
https://ieeexplore.ieee.org/document/8790965
Grant Number
EP/M020398/1
Publication Status
Published
Date Publish Online
2019-08-07