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Design of Artificial Retina Chip With Incident Light Based Stimulation and Supply

Mohajeri, Roya | 2011

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 41675 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Fardmanesh, Mehdi
  7. Abstract:
  8. Blindness is one of the destructive results of retinal diseases. Artificial retina is a device which can help blind people with AMD and RP diseases to restore their vision. Prevalent approaches to artificial retina use an external power supply and processor which the data and energy is transmitted to eye through an inductive link. Taking advantages of solar power, in this project we proposed a design which the required stimulation data and energy is produced internally so the patients don’t have to carry the processor and external power supply that is of major concern for them. This is the most important advantage of this device which doesn’t need any maintenance or battery either. In this device solar cells are used as both the power source and the sensor of a circuit which we designed in an integrated form to produce the stimulus pulses to be injected to the related retinal cells. In this design each pixel has its own independent sensor and circuit. The proposed device uses thin film monocrystalline silicon solar cell which the short circuit current of the cell is found to be approximately 23.45 nA in 100 µm2 area (at noon). Hence the required pulses with frequencies in range of 10-50 Hz can be produced. According to implemented design and calculations, we have highest frequency of pulses at noon and lowest frequency at sunset.
    The circuit which does processing and frequency adjustment according to the input light intensity is designed in 0.18 µm and all simulations are performed with ADS software. The output of the designed circuit is the stimulus pulse to retina and in order to increase the number of pixels, we minimized the size of them as far as possible that is why the designed circuit works with enough low power to be able to operate with the provided power by the solar cell of each pixel. The power consumption of the circuit is approximately 13 nanowatt which shows that the circuit is so low power. We have also proposed a topology for fabrication of this device.

  9. Keywords:
  10. Artificial Retina ; Visual Prosthesis ; Bioinspired Vision

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