SU-8 Microelectrode Fluidic Channel Fabrication
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Solution Overview
Problem
Current microelectrodes for neural implants have short lifespans due to cellular responses and tissue encapsulation, limiting their clinical practicality, and existing methods for incorporating fluidic channels face challenges in scalability, reproducibility, and precision dimension control.
Innovation Solution
The development of microelectrodes with embedded fluidic channels constructed from negative photoresist SU-8, which mitigates immune responses and enhances neural growth, using novel methods for manufacturing and sealing to improve scalability and reproducibility, including partial sealing of fluidic channels and device separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If traditional dielectric sealing methods are used to fabricate fluidic channels, then channel sealing is achieved, but deliverable volume is limited
Solution Approach 1:
The patent removes the traditional dielectric sealing layer and replaces it with a bonded roof structure. The fluidic channel is formed by etching through the substrate, and the roof is bonded directly to the channel walls, eliminating the need for dielectric sealing and sacrificing material. This extraction of the dielectric sealing function allows for increased deliverable volume while maintaining channel integrity.
Solution Approach 2:
Instead of sealing the channel from the outside with dielectrics, the patent inverts the approach by bonding the channel roof directly to the channel walls from the inside. This inversion of the sealing mechanism allows the channel structure itself to define the fluidic pathway, maximizing deliverable volume while ensuring precise sealing through direct bonding.
2Ease of manufacture
If bonding technique is used to construct fluidic channels, then channel formation is simplified, but adhesion strength is low and alignment is poor
Solution Approach 1:
The patent modifies the bonding parameters by using specific bonding materials and processes that enhance adhesion strength. The roof structure is bonded to the channel walls using materials and methods that provide strong mechanical and chemical bonding, overcoming the limitations of traditional bonding techniques. This parameter optimization maintains ease of manufacture while significantly improving adhesion strength and alignment precision.
3Duration of action of stationary object
If microelectrodes are implanted for long-term use, then neural recording capability is maintained, but cellular responses cause tissue encapsulation reducing lifespan
Solution Approach 1:
The patent introduces fluidic channels as an intermediary system between the electrode and the neural tissue. These channels enable the delivery of pharmacological agents that can modulate the cellular response to implantation. By using the fluidic channels to deliver anti-inflammatory drugs, growth factors, or other therapeutic agents, the electrode interface is protected from harmful encapsulation, thereby extending electrode lifespan while maintaining neural recording capability.
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 use of SU-8 microelectrodes with fluidic channels extends the longevity of neural electrodes by reducing tissue encapsulation and enhancing neural growth, while being more cost-effective, simpler to fabricate, and more scalable, with improved customization options.
Implementation Method 1
The shank and the fluidic channel are both constructed out of the negative photoresist, SU-8
Data Source
AI summary
A multielectrode array with a fluidic channel and its method of fabrication are presented here. In accordance with various embodiments, the present invention allows for scalability, reproducibility, and precision dimension control by utilizing a lithography dependent process. In one embodiment, the present invention provides for a microelectrode that is a neural implant, with the microelectrode configured for connection to a fluidic channel. In another embodiment, the fluidic channel may deliver growth factors and/or drugs.