Multiplexed BCI Shanks with Front-End Noise Reduction
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Solution Overview
Problem
Existing brain computer interfaces (BCIs) face limitations in scalability, noise reduction, and biocompatibility due to the need for extensive output wiring and high power consumption, which restricts their ability to cover large areas of the cortex with high resolution and accuracy.
Innovation Solution
The development of a brain computer interface system that incorporates actively multiplexed electrodes with front-end circuits for noise reduction, and a flexible, rollable design to enhance biocompatibility and scalability, allowing for simultaneous recording and stimulation across thousands of electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If extensively wired output traces are used to connect each electrode, then signal transmission reliability is improved, but device complexity and scalability deteriorate
Solution Approach 1:
Multiple electrode signals are merged onto shared output traces through multiplexing. The patent implements a multiplexer that combines signals from multiple electrodes onto fewer output traces, reducing wiring complexity while maintaining signal integrity through time-division multiplexing techniques.
Solution Approach 2:
The electrode array is divided into multiple groups or channels, each with its own multiplexer. This segmentation allows independent multiplexing of different electrode groups, reducing the overall wiring complexity while maintaining reliable signal transmission from each segment.
2Measurement precision
If high power consumption is accepted for active noise reduction circuits, then signal-to-noise ratio is improved, but biocompatibility and scalability deteriorate
Solution Approach 1:
Active noise reduction circuits are implemented locally at strategic positions rather than uniformly across all electrodes. The patent places multiplexers and signal conditioning circuits at specific locations, providing local noise reduction where most needed while minimizing overall power consumption density.
Solution Approach 2:
The multiplexing operation uses periodic switching to sequentially connect different electrode groups to shared output traces. This periodic action allows active circuits to operate intermittently rather than continuously, reducing power consumption density while maintaining effective noise reduction during signal acquisition periods.
3Ease of operation
If flexible and rollable design is implemented to enhance biocompatibility, then ease of insertion and tissue compatibility are improved, but manufacturing precision deteriorates
Solution Approach 1:
The electrode array is constructed using flexible substrates and thin-film fabrication techniques. The patent employs flexible circuits and thin-film deposition methods to create a rollable, biocompatible device that can be easily inserted into brain tissue while maintaining manufacturing precision through controlled fabrication processes.
Data Source
AI summary
A brain computer interface for interfacing with a brain of a subject is provided. The brain computer interface includes one or more shanks. Each shank includes an array of pixels and output traces. Each pixel includes an electrode and a front-end circuit positioned at a site of the electrode. The front-end circuit is configured to reduce noise in signals recorded by the electrode, and further configured to multiplex the signals. A density of power consumption of the each pixel is equal to or less than 1 μW per area of 50 μm by 50 μm. The output traces are electrically coupled with the array of pixels. A number of output traces is less than a number of pixels in the array due to multiplexing. The one or more shanks are configured to be inserted on and/or into a brain of a subject.