Microwave dielectric sensing of free-flowing, single, living cells in aqueous suspension
Research output: Contribution to journal › Article
Colleges, School and Institutes
- Imperial College London
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.
|Journal||IEEE Journal of Electromagnetics, RF and Microwaves in Medicine and Biology|
|Publication status||Published - 7 Aug 2019|
- Biological cells, biosensors, Cells (biology), dielectric, Dielectric measurement, Dielectrics, microfluidics, Microwave measurement, microwave sensors, Microwave theory and techniques, permittivity, resonators, Sensitivity, Sensors