Cervical tissue hydration level monitoring by a resonant microwave coaxial probe

Choi, Heungjae ORCID: https://orcid.org/0000-0003-1108-293X, Barker, Emilia, Abduljabar, Ali A., Anumba, Dilly and Porch, Adrian ORCID: https://orcid.org/0000-0001-5293-8883 2022. Cervical tissue hydration level monitoring by a resonant microwave coaxial probe. Sensors 22 (23) , 9527. 10.3390/s22239527

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Abstract

Cervical tissue hydration level is one of the most important parameters to monitor in the early diagnosis of preterm birth. Electrical-impedance-spectroscopy-based techniques are often used, but they suffer from limited accuracy. Open microwave coaxial probes have been widely used as a broadband dielectric characterization technique for human tissue samples due to their versatility, but with limited accuracy due to their nonresonant nature. In this work, a resonant microwave open coaxial probe with multiple harmonic resonances is proposed as a sensing platform for tissue-hydration-level monitoring. The mechanical design was analyzed and verified by finite-element full 3D electromagnetic simulation and experiments. Dominant sources of errors and the ways to mitigate them were discussed. In vitro experiments were carried out on human cervix samples to verify the precision and accuracy by comparing the results to a commercial skin-hydration sensor. The proposed sensor shows mean fractional frequency shift of (3.3 ± 0.3) × 10−4 per unit % over the entire data. This translates into an absolute frequency shift (ΔfN) of 252 ± 23 kHz/%, 455 ± 41 kHz/%, and 647 ± 57 kHz/% at second, fourth, and sixth harmonic resonance, respectively.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Engineering
Publisher:	MDPI
ISSN:	1424-8220
Date of First Compliant Deposit:	29 November 2022
Date of Acceptance:	29 November 2022
Last Modified:	15 May 2023 07:27
URI:	https://orca.cardiff.ac.uk/id/eprint/154554

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