Flexible Retina Prosthesis Conformal Substrate Design
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Solution Overview
Problem
Conventional retinal prosthesis devices are limited by the size of wiring implants, image resolution, and mismatch between micro electrodes and non-planar retina tissues, leading to restricted field of view and image resolution, which hinders effective vision restoration for patients with age-related macular disease and retinitis pigmentosa.
Innovation Solution
A flexible integrated circuit device with a CMOS chip that integrates micro electrodes, photo sensors, and signal processing, capable of conforming to the retina's shape, featuring a mosaic of sub-modules, perforations for fluid flow, and adjustable electrode heights to target specific neuron layers, along with on-chip signal processing and external calibration for personalized stimulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional planar micro electrode chips are used, then manufacturing is simpler, but the device cannot conform to non-planar retina tissues causing additional interferences and limiting image resolution
Solution Approach 1:
The patent employs a flexible substrate that can be conformally shaped to match the curved surface of the retina. The micro electrode array is fabricated on this flexible substrate, allowing the entire device to bend and conform to the non-planar retinal surface, thereby eliminating shape mismatch interference and improving image resolution without significantly complicating the manufacturing process.
Solution Approach 2:
The patent utilizes a flexible substrate (thin film) as the base for the micro electrode array. This flexible substrate can be bent and shaped to conform to the curved retinal surface, allowing the device to adapt to the non-planar geometry of the retina while maintaining simple manufacturing processes associated with planar fabrication techniques.
2Manufacturing precision
If the number of micro electrodes is increased to improve image resolution, then more wiring implants are required, but the field of view becomes severely limited due to size limitation on wiring implant
Solution Approach 1:
The patent integrates the micro electrode array, driving circuitry, and other functional components onto a single flexible substrate. This monolithic integration eliminates the need for separate wiring implants to connect multiple chips, allowing a high density of micro electrodes to be packed into a compact area while maintaining a large field of view.
Solution Approach 2:
The flexible substrate serves multiple functions simultaneously: it provides the structural base for the micro electrode array, acts as the interconnection medium replacing separate wiring implants, and enables compact integration of driving circuitry. This multi-functionality allows high electrode density without proportionally increasing the overall device area.
3Ease of manufacture
If separate driving circuit chips are used, then circuit design is simpler, but the number of electrical interconnections increases significantly imposing ceilings on achievable number of pixels
Solution Approach 1:
The patent combines the driving circuitry with the micro electrode array on the same flexible substrate, creating an integrated device. This integration dramatically reduces the number of external interconnections required, as the driving circuits are directly connected to the electrodes through on-substrate conductors rather than requiring numerous off-chip wire bonds or connectors.
Data Source
AI summary
Fabrication methods for a flexible device for retina prosthesis are described. Layered structures including an array of pixel units may be formed over a substrate. Each pixel unit may comprise a processing circuitry, a micro electrode and a photo sensor. A first set of biocompatible layers may be formed over the layered structures. The substrate may be thinned down to a controlled thickness of the substrate to allow bending of the substrate to the curvature of a retina. A second set of biocompatible layers may be formed over the thinned substrate. The second set of biocompatible layers may be in contact with the first set of biocompatible layers to form a biocompatible seal wrapping around the device to allow long-term contact of the device with retina tissues. Micro electrodes of the pixel units may be exposed through the openings of these biocompatible layers.