Highly sensitive lossy tunable permittivity sensor
Casacuberta Orta, Pau (Universitat Autònoma de Barcelona. Departament d'Enginyeria Electrònica)
Vélez Rasero, Paris (Universitat Autònoma de Barcelona. Departament d'Enginyeria Electrònica)
Su, Lijuan (Universitat Autònoma de Barcelona. Departament d'Enginyeria Electrònica)
Canalias, Xavier (Universitat Autònoma de Barcelona. Departament d'Enginyeria Electrònica)
Martín, Ferran (Martín Antolín) (Universitat Autònoma de Barcelona. Departament d'Enginyeria Electrònica)

Date:	2024
Abstract:	This letter presents a novel lossy tunable permittivity sensor that enhances sensitivity through a controllable conductivity method using a junction field-effect transistor (JFET) in the ohmic region. The sensor, a one-port reflective-mode device, includes a coplanar waveguide (CPW) ending in a step impedance resonator (SIR) as the sensing element, with the JFET bridging the SIR patch and ground. The high sensitivity is achieved by virtue of the strong shift in the phase of the reflection coefficient at resonance experienced by varying the dielectric constant of the material under test (MUT). This device not only serves as a permittivity sensor but also for tracking variables linked to permittivity changes. Our experimental results uniquely demonstrate that sensitivity to minute perturbations can be significantly enhanced by tuning losses. The prototype, designed and constructed for detecting submillimeter proximity changes with a dielectric slab, achieves a peak sensitivity of 2291°/mm within a compact 8. 5×12 -mm footprint.
Grants:	Agencia Estatal de Investigación PID2022-139181OB-I00 Agencia Estatal de Investigación RYC2022-035819-I Agencia Estatal de Investigación PDC2021-121085-I00 Agencia Estatal de Investigación PID2019-103904RB-I00 Agencia Estatal de Investigación IJC2019-040786-I Agencia Estatal de Investigación FPU20/05700 Agencia Estatal de Investigación PREP2022-000364 Agència de Gestió d'Ajuts Universitaris i de Recerca 2021/SGR-00192
Rights:	Tots els drets reservats.
Language:	Anglès
Document:	Article ; recerca ; Versió acceptada per publicar
Subject:	Coplanar waveguide (CPW) ; Junction field-effect transistor (JFET) ; Lossy sensor ; Permittivity sensor ; Phase-variation sensor ; Tunable sensor
Published in:	IEEE Microwave and Wireless Technology Letters, Vol. 34, issue 6 (June 2024) , p. 687-690, ISSN 2771-957X

DOI: 10.1109/LMWT.2024.3383162

Available from: 2026-06-30 Postprint

The record appears in these collections:
Research literature > UAB research groups literature > Research Centres and Groups (research output) > Engineering > CIMITEC-UAB
Articles > Research articles
Articles > Published articles