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Design and Fabrication of High-Frequency Bio-Impedance Spectroscopy System based on Microfluidics

Mousavi Madani, Arian | 2026

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 58815 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Fardmanesh, Mehdi
  7. Abstract:
  8. In this research, the design, fabrication, and characterization of a microfluidic chip integrated with gold electrodes for performing high-frequency impedance spectroscopy of biological samples in cellular studies are presented. The fabrication process of the chip includes microfabrication of electrodes on a glass substrate, design and implementation of polymeric microchannels, and precise integration of these two components. The electrodes were fabricated using titanium as a buffer layer and gold as the primary electrode material, and their patterning was carried out through photolithography and chemical etching. To form the microchannels, molds with a purpose-designed geometry were developed to enable controlled trapping of biological samples with different sizes within the measurement region, thereby ensuring stable conditions for impedance measurements. For the fabrication of the microfluidic component, polydimethylsiloxane (PDMS) was employed. After molding and curing, the PDMS structure was bonded to the glass substrate containing the electrodes using oxygen plasma surface activation. The surface activation and bonding processes were optimized by adjusting parameters such as plasma power, exposure time, and gas flow rate to achieve a permanent, uniform, and leakage-free bond between PDMS and glass. Precise alignment of the microchannels with the underlying electrodes at this stage was critical and played a decisive role in the accuracy of the impedance measurements. Subsequently, the experimental setup—comprising the fluid injection system, electrical connections, and impedance measurement instrumentation—was implemented, and the impedance response of the system was investigated over a specified frequency range. The obtained results indicate that the presence of a biological sample within the measurement region leads to significant variations in the impedance response of the chip, which are dependent on the electrical and dimensional properties of the particles. Finally, the experimental results were compared with the theoretical predictions obtained from the simulations, showing good agreement. The findings of this study demonstrate that the proposed microfluidic chip can serve as an efficient platform for impedance-based analysis of biological particles and biosensing applications. Impedance spectroscopy of different cells can enable the detection of cell health status, size, and other properties, depending on the frequency range and cell type
  9. Keywords:
  10. Bioimpedance Spectroscopy ; Microfluidic System ; High Frequencies ; Microfabrication

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