Research | amirebrahimi

Metamaterials-Inspired Sensors

Metamatrials-based particles such as split-ring resonators (SRRs), electric-LC (ELC) resonators and their complementary counterparts have shown great potentials for sensing and detection applications. At resonance, the metamaterial-based particles provide highly dense concentration of electromagnetic fields that are very sensitive to the geometrical or material change around them. We demonstrated several novel sensing structures using metamaterials for mechanical misalignment detection, microfluidic, and solid dielectric materials characterizations. Our new designs of sensors show enhance sensitivity and detection range compared with the traditional microwave sensing devices. Our sensors have potential applications in various science and industry applications such as chemical detection, biological characterizations, water quality monitoring, and etc.

A. Ebrahimi, J. Scott, K. Ghorbani, “Ultra-high sensitivity microwave sensor for microfluidic complex permittivity measurement,” IEEE Trans. Microwave Theory and Techniques. DOI: 10.1109/TMTT.2019.2932737

A. Ebrahimi, J. Scott, K. Ghorbani, “Dual-mode resonator for permittivity and thickness measurement of dielectrics,” IEEE Sensors Journal, DOI: 10.1109/JSEN.2019.2941753

A. Ebrahimi, J. Scott, K. Ghorbani, “Transmission lines terminated with LC resonators for differential permittivity sensing,” IEEE Microwave and Wireless Components Letters, vol. 28, no. 12, pp. 1149 – 1151, December 2018.

A. Ebrahimi, J. Scott, K. Ghorbani, “Differential sensors using microstrip lines loaded with two split ring resonators,” IEEE Sensors Journal, vol. 18, no. 14, pp. 5786 – 5793, July 2018.

A. Ebrahimi, W. Withayachumnankul, S. Al-Sarawi and D. Abbott, “Metamaterial-inspired rotation sensor with wide dynamic range,” IEEE Sensors Journal, vol. 14, no. 8, pp. 2609-2614, Aug. 2014.

A. Ebrahimi, W. Withayachumnankul, S. Al-Sarawi and D. Abbott, “High-Sensitivity metamaterial-inspired sensor for microfluidic dielectric characterization,” IEEE Sensors Journal, vol. 14, no. 5, pp. 1345-1351, May 2014.

Metamaterials-Based Planar Filters

The small-size and high-quality factor (Q) resonance of the metamaterials-based resonators makes them ideal choices for implementation of novel planar filters for communication systems and integrated electronic devices. Our research in this area is focused on the design of very compact filters using dual-mode metamaterial resonators. Applications range from compact bandpass and bandstop filters, tunable filters, and differential filters and transmission lines for supressing the common-mode noise and interferences in high-speed analog and mixed-signal systems.

A. Ebrahimi, K. Wang, T. Baum, J. Scott, and K. Ghorbani, "Differential transmission lines loaded with magnetic LC resonators and application in common mode suppression," IEEE Trans. on Circuits and Systems I: Regular Papers, DOI: 10.1109/TCASI.2019.2909036.

A. Ebrahimi, T. Baum, J. Scott, K. Ghorbani, “Continuously tunable dual-mode bandstop filter,” IEEE Microwave and Wireless Components Letters, vol. 28, no. 5, pp. 419-421, May 2018.

A. Ebrahimi, T. Baum, K. Ghorbani, “Differential bandpass filters based on dumbbell-shaped defected ground resonators,” IEEE Microwave and Wireless Components Letters, vol. 28, no. 2, pp. 129-131, Feb. 2018.

A. Ebrahimi, W. Withayachumnankul, S. Al-Sarawi and D. Abbott, “Compact second-order bandstop filter based on dual-mode complementary split-ring resonator,” IEEE Microwave and Wireless Components Letters, vol. 26, no. 8, pp. 571-573, August 2016.

A. Ebrahimi, W. Withayachumnankul, S. Al-Sarawi and D. Abbott, “Dual-mode behavior of the complementary electric-LC resonators loaded on transmission line: Analysis and applications,” Journal of Applied Physics, vol. 116, no. 8, art. no. 083705, 2014.

A. Ebrahimi, W. Withayachumnankul, S. Al-Sarawi and D. Abbott, “Compact dual-mode wideband filter based on complementary split-ring resonator,” IEEE Microwave and Wireless Components Letter, vol. 24, no. 3, pp. 152-154, March 2014.

Frequency Selective Surfaces (FSSs)

Frequency selective surfaces (FSSs) are spatial filters made of two dimensional (2D) periodic arrangement of metallic elements printed on a dielectric substrate. Based on the unit cell geometry and arrangement, the FSS can show bandpass/bandstop filtering responses, absorb the incident electromagnetic wave, perform polarization manipulation, etc. The focus of our research is to design and implement FSSs structures using miniaturized non-resonant unit cells for a wide frequency ranges from microwave up to terahertz regime. The miniaturized elements FSSs offer a high stability of frequency response with respect to the oblique incidences and non-planar phase fronts of the EM incident wave.

A. Ebrahimi, R. T. Ako, W. Lee, M. Bhaskaran, S. Sriram, and W. Withayachumnankul, “Hig-Q terahertz absorber with stable angular response,” IEEE Trans. on Terahertz Science and Technology, vol. 10, no. 2, pp. 204-211, Jan. 2020.

A. Ebrahimi, Z. Shen, W. Withayachumnankul, S. Al-Sarawi and D. Abbott, “Varactor-tunable second-order bandpass frequency selective surface with embedded bias network,” IEEE Trans. on Antennas and Propagation, vol. 64, no. 5, pp. 1672 – 1680, March 2016.

A. Ebrahimi, S. Nirantar, W. Withayachumnankul, M. Bhaskaran, S. Sriram, S. Al-Sarawi and D. Abbott, “Second-order terahertz bandpass frequency selective surface with miniaturized elements,” IEEE Trans. on Terahertz Science and Technology, vol. 5, no. 5, pp. 761-769, July 2015.