Nanoscale electric permittivity of single bacterial cells at gigahertz frequencies by scanning microwave microscopy Biagi, Maria Chiara Fabregas, Rene Gramse, Georg Van Der Hofstadt, Marc Juarez, Antonio Kienberger, Ferry Fumagalli, Laura Gomila, Gabriel Scanning Microwave Microscopy Single Bacteria Electric Permittivity Topographic Cross-Talk We quantified the electric permittivity of single bacterial cells at microwave frequencies and nanoscale spatial resolution by means of near-field scanning microwave microscopy. To this end, calibrated complex admittance images have been obtained at ∼19 GHz and analyzed with a methodology that removes the nonlocal topographic cross-talk contributions and thus provides quantifiable intrinsic dielectric images of the bacterial cells. Results for single Escherichia coli cells provide a relative electric permittivity of ∼4 in dry conditions and ∼20 in humid conditions, with no significant loss contributions. Present findings, together with the ability of microwaves to penetrate the cell membrane, open an important avenue in the microwave label-free imaging of single cells with nanoscale spatial resolution. 2025-02-02T10:02:19Z 2025-02-02T10:02:19Z 2015 journal article https://hdl.handle.net/10481/101777 10.1021/acsnano.5b04279 eng People-2012-ITN/FP7/317116 http://creativecommons.org/licenses/by-nc-nd/4.0/ open access Attribution-NonCommercial-NoDerivatives 4.0 Internacional