Biomedical Impedance Matching, Time-Varying Waveguides, Asymmetrical Transmission with Chiral Medium and Beyond: Research Experiences at a Primarily Undergraduate Institution

This seminar will highlight several research activities led by Dr. Cakmak at Grand Valley State University (GVSU), focusing on introducing undergraduate students to the research world of Electromagnetics. In this context, Dr. Cakmak will demonstrate how Electromagnetics serves as a powerful enabler for cultivating research habits at a Primarily Undergraduate Institution.

Three main research directions at microwave frequencies will be discussed:

1. Microwave coupling to the human torso,

2. Time-varying microstrip transmission lines, and

3. Asymmetric transmission using Frequency Selective Surfaces (FSS).

Microwave imaging plays an important role in detecting tumors in certain types of cancer. However, efficiently coupling electromagnetic waves into the human body remains challenging due to impedance mismatches at the skin–air interface. Furthermore, anatomical variability among patients and reactive near-field measurement limitations introduce additional complexities. To address these issues, a new type of actively modulated metasurface has been developed as an impedance-matching medium to enhance coupling efficiency and provide robustness against such variations. In a separate study, microwave strip waveguides are employed to explore signal modulation capabilities of microstrips without relying on active components. When loaded with PIN diodes, microstrips can effectively gate the transmission of microwaves, functioning as a time-varying electromagnetic system. A proof-of-principle demonstration shows amplitude modulation that operate at Wi-Fi and Bluetooth frequencies. Another research effort involves cascading chiral media with FSS layers to achieve pronounced asymmetric transmission. It is demonstrated more than 30 dB of one-way transmission, underscoring the potential of such composite systems for advanced microwave control and isolation applications.

Additional Information:

Dr. Atilla Ozgur Cakmak is an Assistant Professor in the Department of Electrical and Computer Engineering at Grand Valley State University (GVSU), Michigan. He joined GVSU in 2021, and his primary research interests lie in the areas of metasurfaces and antennas. Dr. Cakmak has authored or co-authored more than 25 peer-reviewed publications and actively contributes to the scholarly community as an associate editor, topical editor, and reviewer in his field.

Dr. Cakmak earned his Ph.D. in Electrical and Electronics Engineering from Bilkent University, Turkey, in 2012. In 2013, he joined The Pennsylvania State University’s Center for Nanotechnology Education and Utilization (CNEU) as a postdoctoral researcher, focusing on solar cell technologies. He later served as an Assistant Teaching Professor at Penn State, beginning in 2018, where he taught courses in nanolithography and nanophotonics within the Department of Engineering Science and Mechanics. As a mentor and educator, Dr. Cakmak is deeply committed to undergraduate and master’s student supervision, fostering hands-on research experiences and professional development through his teaching and research activities.