Microneedle Sidewall Channels Prevent Clogging
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Solution Overview
Problem
Conventional microneedle arrays face issues with clogging and inefficient fluid throughput due to small channel sizes and localized fluid injection/sampling, which limits their effectiveness in applications requiring simultaneous and reliable fluid handling.
Innovation Solution
A multiport microneedle design with microfluidic channels exiting perpendicular to the needle sidewalls, rather than the tip, to prevent clogging and enable simultaneous injection/sampling, fabricated using silicon micromachining and isotropic etching techniques, allowing for separate and independent fluid communication channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If microfluidic channels are made small to increase channel density, then the number of channels per needle increases, but particles stick to channels and cause clogging
Solution Approach 1:
The patent transitions from tip-oriented channel exits to sidewall-oriented channel exits. This dimensional change in the exit orientation prevents particles from adhering to the channel walls during fluid flow, thereby eliminating clogging while maintaining high channel density. The sidewall exits create a flow pattern where particles are carried along the channel rather than sticking to surfaces.
2Productivity
If multiple microneedles are arranged in an array to increase throughput, then fluid handling capacity increases, but the device takes up more space on the substrate
Solution Approach 1:
The patent combines multiple microfluidic channels into a single needle structure, allowing multiple fluids to be injected or sampled simultaneously through one needle. This merging of functions replaces the need for multiple separate needles, increasing fluid throughput while reducing the substrate area occupied by the device.
Solution Approach 2:
The multiport microneedle structure performs multiple functions (injection and sampling of different fluids) through a single integrated needle. This multi-functionality allows the device to achieve high throughput without requiring multiple separate needle elements, thereby reducing the overall device footprint on the substrate.
3Ease of operation
If microchannel exits are located at the tip of the needle, then injection is direct, but simultaneous injection and sampling directs fluid to a very local area causing unreliable sampling
Solution Approach 1:
The patent segments the channel exits into multiple locations on the sidewall of the needle rather than concentrating them at the tip. This segmentation allows different channels to target different locations, enabling simultaneous injection and sampling at spatially separated points, which improves sampling reliability by preventing fluid mixing and contamination.
4Ease of operation
If microchannel exits are made wide and accessible from the top, then accessibility improves, but the structure becomes prone to clogging
Solution Approach 1:
The patent changes the exit orientation from top-accessible (vertical) to sidewall-accessible (lateral). This dimensional change in exit orientation maintains accessibility while preventing particles from adhering to channel walls during flow, thereby eliminating clogging while preserving ease of operation.
Data Source
AI summary
The application relates to microfluidic needles and their manufacturing methods. The microfluidic needle comprises an interface portion containing at least one fluid communication channel, an elongated needle portion (40) projecting away from the interface portion (44), the needle portion having a tip and sidewalls connecting the tip to the interface portion, and at least two microfluidic channels (43 A-B) within the needle portion in fluidic connection with the at least one communication channel, the microfluidic channels being at least partly oriented parallel to the elongated needle portion. According to the application, the microfluidic channels exit the needle portion at the sidewalls of the needle portion. The needle may be fabricated by ALD-assisted silicon micromachining. The needle can be used for injection and/or sampling fluids to/from tissue or individual cells.