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Designing Electrophysiological Characterization System of Biological Cells Based on the Use of Nanostructured Electrodes

Vafaiee, Mohadeseh | 2019

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 52560 (48)
  4. University: Sharif University of Technology
  5. Department: Institute for Nanoscience and Nanotechnology
  6. Advisor(s): Vossoughi, Manouchehr; Sasanpour, Pezhman; Mohammadpour, Raheleh
  7. Abstract:
  8. In the last half century, the recording of the electrophysiological activities of the neurons has been one of the most effective methods for neuroscience development. One of the techniques used to record the activity of the nerve cells is the use of multi-electrode arrays (MEAs). Current MEAs still face limitations such as low signal-to-noise ratio (SNR) and low spatial resolution. There is a need to develop arrays that are smaller in size and have less impedance to achieve better spatial resolution and lower noise levels. The main focus of this research is on the designing and fabrication of multi-electrode arrays and improvement of their properties using nanostructures and conductive polymers. In order to design the electrode using the finite element method, the effect of shape, geometry and structure of the electrode on its performance was investigated. The results of the simulations showed that the structures with larger perimeter and sharper angles create a larger electrical double layer capacitance. The results indicate that considering the same surface area, the extrude electrodes require lower level of stimulation comparing with the other shapes of the electrodes. Accordingly, several types of structures were designed and fabricated. The fabricated electrodes include gold-based electrodes, FTO, gold nanosheets, graphene, carbon nanotubes, conductive polymers, and hybrid electrodes. Each electrode was characterized after fabrication and evaluated for biocompatibility and stability. Finally, the presence of nanostructures and conductive polymers improved the electrode properties including impedance, effective surface area and roughness. Among them, the carbon nanotube-based electrode showed the lowest impedance; In the presence of carbon nanotubes, the impedance of the gold electrode reached 7.9 Ω from 10.8 Ω at 1 kHz. Experimental results showed good biocompatibility and stability of the fabricated electrodes, during the recording and excitation processes. Subsequently, for electronic signal recording, an electronic system including adjustable amplifier circuits, stimulation and recording system was designed and fabricated. Finally, multi-electrode arrays were successfully used to record neural signals with the fabricated electronic system
  9. Keywords:
  10. Multi-Electrode Arrays (MEA) ; Action Potential ; Nanostructure ; Neurons Signals ; Nerve Tissue Engineering ; Impedance ; Electrophysiology

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