Polyimide Neural Probe with Micro-ILEDs for Reduced Tissue Damage
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Solution Overview
Problem
Existing neural probes face challenges in achieving long-term functionality within the brain due to tissue damage, harsh tissue reactions, and the need for spatiotemporal resolution in neuronal circuitry interpretation, particularly with rigid silicon shanks.
Innovation Solution
A flexible probe assembly with a polyimide-based shank, integrated with micro-ILEDs and recording electrodes, designed to conform around anatomical structures, allowing for chronic neural stimulation and monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid silicon shank is used for the probe, then structural strength and stability are improved, but tissue damage increases and long-term functionality deteriorates
Solution Approach 1:
The patent replaces rigid silicon shanks with flexible polymer-based shanks that can conform to brain tissue. The flexible shank includes multiple polymer layers (e.g., polyimide, parylene, PDMS) that provide mechanical compliance, reducing tissue damage while maintaining structural integrity for long-term implantation.
Solution Approach 2:
The probe employs composite material structures combining multiple polymer layers with embedded functional elements (electrodes, LEDs). This composite approach allows the shank to achieve both flexibility for tissue compatibility and sufficient strength to support functional components during chronic implantation.
2Object-affected harmful factors
If the probe size is reduced to minimize tissue damage, then minimally-invasive capability is improved, but structural strength and stability worsen
Solution Approach 1:
The flexible polymer shank can be fabricated in thin, minimally-invasive dimensions while maintaining adequate strength through the inherent mechanical properties of the polymer materials and their multi-layer construction, allowing small form factor without sacrificing structural integrity.
Solution Approach 2:
The composite polymer structure provides enhanced strength-to-weight and strength-to-size ratio, enabling the probe to be made smaller and thinner for minimally-invasive implantation while still maintaining sufficient mechanical strength to support electrodes and functional components.
3Manufacturing precision
If a rigid probe structure is used, then manufacturing precision is improved, but adaptability to anatomical structures worsens
Solution Approach 1:
The flexible polymer shank can be manufactured with precise dimensions and patterns using standard flexible PCB and thin-film fabrication techniques, then conforms to irregular anatomical structures in vivo, achieving both manufacturing precision and biological adaptability.
Solution Approach 2:
The probe transitions from a static rigid structure to a dynamic flexible structure that can adapt its shape in response to anatomical variations, allowing the same precisely-manufactured probe to conform to different brain regions and anatomical configurations.
4Object-affected harmful factors
If the probe material is made softer to reduce tissue reaction, then biocompatibility is improved, but structural strength worsens
Solution Approach 1:
The multi-layer polymer composite structure achieves an optimal balance between softness for biocompatibility and strength for structural support, with each layer contributing different mechanical properties that collectively provide both tissue compatibility and adequate strength.
Solution Approach 2:
The flexible polymer materials inherently provide a softer, more biocompatible interface with tissue while maintaining sufficient structural strength through their viscoelastic properties and multi-layer construction, reducing foreign body response compared to rigid materials.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The flexible probe assembly enables long-term neural stimulation and recording, minimizing tissue damage and maintaining functionality for over a month, with improved spatiotemporal resolution and reduced tissue reaction.
Implementation Method 1
treating a first polymer layer to increase a surface area on an adhesion portion of the first polymer layer, and adhering the first polymer layer to a second polymer layer
Implementation Method 2
inorganic LED (ILED) integrated optogenetic-based selective cell protein stimulation, which stimulates genetically modified opsin (such as gene expressed channelrhodopsin-2) upon illumination of LED light
Data Source
AI summary
A probe assembly comprising a probe shank having a plurality of polymer layers. The plurality of polymer layers includes a first polymer layer and a second polymer layer. The first polymer layer and the second polymer layer sandwich one or more recording traces or one or more stimulating traces such that the first polymer layer, the second polymer layer, the one or more recording traces, and the one or more stimulating traces are configured to conform around an anatomical structure. A method of manufacturing involves treating the first polymer layer to increase a surface area on an adhesion portion of the first polymer layer. Another method of manufacturing involves monolithically fabricating a light emitting diode (LED) that is equal to or less than 500 square microns, and applying a polyimide layer to form a probe shank around the LED.