Thesis Defence: PEDOT:PSS Microwave Structures: Fabrication, Electromagnetic Properties and Applications

Marzieh Dordanihaghighi, supervised by Mohammad H. Zarifi, will defend their thesis titled “PEDOT:PSS Microwave Structures: Fabrication, Electromagnetic Properties and Applications” in partial fulfillment of the requirements for the degree of Master of Applied Science in Electrical Engineering.

An abstract for Marzieh Dordanihaghighi’s thesis is included below.

Defences are open to all members of the campus community as well as the general public. Please email mohammad.zarifi@ubc.ca to receive the Zoom link for this defence.

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ABSTRACT

Electronic waste (e-waste) has become an environmental concern with the advent of the Internet of Things (IoT) and the new generation of wireless technologies due to the substantial increase in the manufacturing of metal-based electronic components. The development of 6G and the trend towards smaller and more powerful devices require materials that offer both high performance and environmental sustainability, highlighting Intrinsically Conductive Polymers (ICPs) as key candidates for future technological advancements. Among different ICPs, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) or PEDOT:PSS stands out as a leading candidate due to its unique physical and electrical properties. Despite the progress made in PEDOT:PSS microwave structures, the detailed behavior of this material in the microwave spectrum and its interaction with electromagnetic waves have remained unexplored. This thesis delves into the electromagnetic properties of PEDOT:PSS-based wired and wireless structures within the microwave regime, investigating factors that influence their microwave response. This research is structured into two primary streams: wired and wireless microwave structures. In the first stream, the study examines the electromagnetic properties of two different PEDOT:PSS-based structures: PEDOT:PSS microstrip lines with variant thicknesses from 2 μm to 16 μm, and PEDOT:PSS patch resonators doped with various concentrations of dimethyl sulfoxide (DMSO) from 0 wt% to 8 wt%. The experimental setup involves measuring the microwave response of these structures across different frequency bands and validating the results with simulations in various software. The findings reveal that the thickness of PEDOT:PSS layers significantly impact the propagation efficiency of microwave signals, and the dopant concentration influences the material’s sensitivity to relative humidity changes, indicating the potential of PEDOT:PSS for utilization in tunable microwave devices. In the second stream, the study investigates multilayer PEDOT:PSS thin films and their absorbing capabilities in the X-band frequency range. It also explores the use of PEDOT:PSS microwave resonator patterned surfaces for wireless humidity detection and non-intrusive liquid sensing applications. The research demonstrates that multilayer structures with varying distances from the electromagnetic source and different layer arrangements exhibit distinct reflection responses. Additionally, the PEDOT:PSS patch resonator array shows promising results as a microwave absorbing surface and a sensitive element for humidity detection. The split ring resonator composed of DMSO-doped PEDOT:PSS and silver nanowires effectively distinguishes between different standard liquids based on their complex permittivity. This comprehensive study advances the understanding of PEDOT:PSS’s behavior in the microwave regime and underscores its suitability and tunability for various microwave applications. The insights gained from this research contribute to the growing body of knowledge on PEDOT:PSS and pave the way for the development of advanced microwave technologies in telecommunications, wireless sensing, and beyond.