Highly programmable digital controller for high-density epi-retinal prosthesis.

Area of Science:

• Biomedical Engineering
• Electrical Engineering
• Neuroscience

Background:

• High programmability is crucial for epi-retinal prostheses to adapt to diverse physiological conditions.
• Limited wireless transmission bandwidth poses a significant challenge for controlling multi-pixel retinal implants.

Purpose of the Study:

• To design and analyze a digital controller for a high-pixel-count (up to 1024) epi-retinal prosthesis.
• To achieve high pixel programmability while minimizing data bandwidth requirements.
• To develop a power-efficient and area-optimized controller suitable for implantable systems.

Main Methods:

• A two-tier architecture was adopted to reduce chip area.
• Key circuit blocks, including an on-chip address generator (OCAG) and a flexible data parser, were developed.
• Multi-clock domain and data gating techniques were employed for power reduction.

Main Results:

• The proposed digital controller achieved a 54.7% reduction in data bandwidth requirement.
• The flexible data parser allowed optimization between data discard rate and maximum frame rate.
• A prototype 256-pixel epi-retinal prosthesis controlled by the digital controller was successfully fabricated using 0.18microm CMOS HV technology.

Conclusions:

• The developed digital controller effectively supports high-pixel-count epi-retinal prostheses with enhanced programmability and reduced bandwidth.
• The design's efficiency and flexibility make it suitable for advanced implantable multi-channel stimulation systems.
• This controller technology has potential applications beyond retinal prostheses, in other neural stimulation devices.