Dissertation Defence: Structural Design and Fabrication of Electrically Conductive Materials for Electromagnetic Interference Shielding and Strain Sensing

Ahmadreza Ghaffarkhah, supervised by Dr. Mohammad Arjmand, will defend their dissertation titled “Structural Design and Fabrication of Electrically Conductive Materials for Electromagnetic Interference Shielding and Strain Sensing” in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Mechanical Engineering.

An abstract for Ahmadreza Ghaffarkhah’s dissertation is included below.

Examinations are open to all members of the campus community as well as the general public. Registration is not required for in person defences.

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ABSTRACT

This thesis investigates the role of structural design in shaping the performance of advanced materials for electromagnetic interference (EMI) shielding and strain/pressure sensing. Four material categories—laminated, 3D printed, polymer nanocomposites, and aerogels—are explored using various fabrication methods.

The journey begins with the synthesis and characterization of foundational nanomaterials, such as Ti3C2Tx, graphene oxide (GO), and magnetic GO (mGO). These materials form the basis of our structures. Laminated structures are then created through versatile drop-casting, yielding highly conductive Ti3C2Tx /PEDOT:PSS films. This approach ensures uniformity, cost-effectiveness, and ease of production. A wet-transfer technique is introduced to adapt these films to complex shapes, providing scalability for EMI shielding applications.

The development continues with laminated 3D-printed structures tailored for EMI shielding and strain sensing. Challenges associated with extrusion printing, including resolution and the need for high electrical conductivity and mechanical flexibility, are addressed. This phase results in additive-free inks for high-resolution extrusion printing and composite structures with outstanding electrical conductivity and mechanical flexibility.

Next, the thesis delves into aerogel-based conductive materials and polymer nanocomposites. A novel “liquid streaming” approach is introduced for aerogel fabrication, using nanoparticle surfactants to stabilize aqueous suspensions of Ti3C2Tx/GO in a nonpolar medium. These aerogels offer simplicity, reduced pre-processing, exceptional EMI shielding effectiveness, specific EMI shielding effectiveness, and low density, enhanced by micro- and macro-scale porosities that significantly improve absorption characteristics. The final chapter presents Janus liquids, enabling the creation of responsive aerogels customized for piezoresistive sensing, human motion monitoring, and EMI shielding with absorption-dominant characteristics. This research deepens our understanding of structural design’s influence on EMI shielding and pressure sensing and showcases the potential of multifunctional materials for future electronic and sensing applications.