Uncooled Insulated Monopole Antenna for Microwave Ablation: Improved Performance with Coaxial Cable Annealing
There is growing interest in measuring the temperature-dependent dielectric properties of bio-tissues using dual-mode techniques (scattering measurements and thermal treatment). Uncooled coaxial antennas are preferred for their direct contact with the measured medium and reduced complexity; however,...
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MDPI AG
2025-06-01
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| Online Access: | https://www.mdpi.com/2076-3417/15/12/6616 |
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| author | Federico Cilia Lourdes Farrugia Charles Sammut Arif Rochman Julian Bonello Iman Farhat Evan Joe Dimech |
| author_facet | Federico Cilia Lourdes Farrugia Charles Sammut Arif Rochman Julian Bonello Iman Farhat Evan Joe Dimech |
| author_sort | Federico Cilia |
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| description | There is growing interest in measuring the temperature-dependent dielectric properties of bio-tissues using dual-mode techniques (scattering measurements and thermal treatment). Uncooled coaxial antennas are preferred for their direct contact with the measured medium and reduced complexity; however, they exhibit structural changes during ablation due to the thermal expansion of polytetrafluoroethylene (PTFE). This paper presents an experimental study on PTFE expansion in an uncooled coaxial insulated monopole antenna in response to changes in the tissue’s thermal environment. Furthermore, it presents a methodology to mitigate these effects through coaxial annealing. The investigation consists of two distinct experiments: characterising PTFE expansion and assessing the effects of annealing through microwave ablation. This was achieved by simulating the thermal effects experienced during ablation by immersing the test antenna in heated peanut oil. PTFE expansion was measured through camera monitoring and using a toolmaker’s microscope, revealing two expansion modalities: linear PTFE expansion and non-linear plastic deformation from manufacturing processes. The return loss during ablation and consequential changes in the ablated lesion were also assessed. Antenna pre-annealing increased resilience against structural changes in the antenna, improving lesion ellipticity. Therefore, this study establishes a fabrication method for achieving an uncooled thermally stable antenna, leading to an optimised dual-mode ablation procedure, enabling quasi-real-time permittivity measurement of the surrounding tissue. |
| format | Article |
| id | doaj-art-4acb88e47eb84d42aae61e94de4d7f0f |
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| issn | 2076-3417 |
| language | English |
| publishDate | 2025-06-01 |
| publisher | MDPI AG |
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| series | Applied Sciences |
| spelling | doaj-art-4acb88e47eb84d42aae61e94de4d7f0f2025-06-25T13:25:25ZengMDPI AGApplied Sciences2076-34172025-06-011512661610.3390/app15126616Uncooled Insulated Monopole Antenna for Microwave Ablation: Improved Performance with Coaxial Cable AnnealingFederico Cilia0Lourdes Farrugia1Charles Sammut2Arif Rochman3Julian Bonello4Iman Farhat5Evan Joe Dimech6Department of Physics, Faculty of Science, University of Malta, MSD 2080 Msida, MaltaDepartment of Physics, Faculty of Science, University of Malta, MSD 2080 Msida, MaltaDepartment of Physics, Faculty of Science, University of Malta, MSD 2080 Msida, MaltaDepartment of Industrial & Manufacturing Engineering, Faculty of Engineering, University of Malta, MSD 2080 Msida, MaltaDepartment of Physics, Faculty of Science, University of Malta, MSD 2080 Msida, MaltaDepartment of Physics, Faculty of Science, University of Malta, MSD 2080 Msida, MaltaDepartment of Electronic Systems Engineering, Faculty of Engineering, University of Malta, MSD 2080 Msida, MaltaThere is growing interest in measuring the temperature-dependent dielectric properties of bio-tissues using dual-mode techniques (scattering measurements and thermal treatment). Uncooled coaxial antennas are preferred for their direct contact with the measured medium and reduced complexity; however, they exhibit structural changes during ablation due to the thermal expansion of polytetrafluoroethylene (PTFE). This paper presents an experimental study on PTFE expansion in an uncooled coaxial insulated monopole antenna in response to changes in the tissue’s thermal environment. Furthermore, it presents a methodology to mitigate these effects through coaxial annealing. The investigation consists of two distinct experiments: characterising PTFE expansion and assessing the effects of annealing through microwave ablation. This was achieved by simulating the thermal effects experienced during ablation by immersing the test antenna in heated peanut oil. PTFE expansion was measured through camera monitoring and using a toolmaker’s microscope, revealing two expansion modalities: linear PTFE expansion and non-linear plastic deformation from manufacturing processes. The return loss during ablation and consequential changes in the ablated lesion were also assessed. Antenna pre-annealing increased resilience against structural changes in the antenna, improving lesion ellipticity. Therefore, this study establishes a fabrication method for achieving an uncooled thermally stable antenna, leading to an optimised dual-mode ablation procedure, enabling quasi-real-time permittivity measurement of the surrounding tissue.https://www.mdpi.com/2076-3417/15/12/6616annealinginsulated monopolelesionmicrowave thermal ablationpolytetrafluoroethylenethermal expansion |
| spellingShingle | Federico Cilia Lourdes Farrugia Charles Sammut Arif Rochman Julian Bonello Iman Farhat Evan Joe Dimech Uncooled Insulated Monopole Antenna for Microwave Ablation: Improved Performance with Coaxial Cable Annealing Applied Sciences annealing insulated monopole lesion microwave thermal ablation polytetrafluoroethylene thermal expansion |
| title | Uncooled Insulated Monopole Antenna for Microwave Ablation: Improved Performance with Coaxial Cable Annealing |
| title_full | Uncooled Insulated Monopole Antenna for Microwave Ablation: Improved Performance with Coaxial Cable Annealing |
| title_fullStr | Uncooled Insulated Monopole Antenna for Microwave Ablation: Improved Performance with Coaxial Cable Annealing |
| title_full_unstemmed | Uncooled Insulated Monopole Antenna for Microwave Ablation: Improved Performance with Coaxial Cable Annealing |
| title_short | Uncooled Insulated Monopole Antenna for Microwave Ablation: Improved Performance with Coaxial Cable Annealing |
| title_sort | uncooled insulated monopole antenna for microwave ablation improved performance with coaxial cable annealing |
| topic | annealing insulated monopole lesion microwave thermal ablation polytetrafluoroethylene thermal expansion |
| url | https://www.mdpi.com/2076-3417/15/12/6616 |
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