Tapered Microneedle Chip for Interstitial Fluid Extraction
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Solution Overview
Problem
Existing microneedle technologies face challenges in efficiently sampling interstitial fluid without using sub-pressure or suction, and are not robust enough for safe use in mammals, with most designs limited to extraction on specific skin types or conditions.
Innovation Solution
A microneedle chip with elongated bodies featuring a capillary bore that gradually decreases in cross-sectional area from the distal to the proximal end, a triangular cross-section, and hydrophilic surfaces, integrated with a substrate fluid channel system that creates under-pressure for enhanced fluid flow, and includes lateral holes to prevent clogging, allowing capillary action for fluid extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If microneedles use uniform cross-sectional capillary bores, then manufacturing is simpler, but fluid flow efficiency is reduced
Solution Approach 1:
The patent applies parameter changes by varying the cross-sectional area of the capillary bore along its length. The bore has a larger cross-sectional area at the distal end and a smaller cross-sectional area at the proximal end, creating a tapered geometry that optimizes capillary pressure and fluid flow efficiency while remaining manufacturable through standard microneedle fabrication processes.
2Ease of manufacture
If microneedles have straight cylindrical bores, then manufacturing is easier, but wetting and fluid flow are reduced
Solution Approach 1:
The patent applies curvature by rounding the corners of the capillary bore cross-section instead of using sharp edges. This rounded geometry improves wetting properties and capillary action, enhancing fluid flow efficiency while being compatible with standard microneedle manufacturing techniques such as laser drilling or etching processes.
3Device complexity
If microneedles lack lateral openings, then structure is simpler, but clogging risk increases
Solution Approach 1:
The patent applies segmentation by incorporating lateral openings or side ports along the length of the microneedle body. These additional openings divide the single fluid path into multiple potential flow paths, reducing the risk of complete clogging by providing alternative routes for fluid to reach the collection reservoir.
4Ease of operation
If microneedles extract ISF without under-pressure, then device operation is simpler, but extraction efficiency is insufficient
Solution Approach 1:
The patent replaces mechanical suction or pumping systems with capillary forces generated by the tapered bore geometry. The varying cross-sectional area creates capillary pressure that actively draws interstitial fluid along the needle length, eliminating the need for external under-pressure mechanisms while maintaining operational simplicity and high extraction efficiency.
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
Enables efficient, safe, and robust sampling of interstitial fluid using capillary forces alone, reducing the risk of clogging and allowing for volume manufacturability, suitable for use in mammals with minimal discomfort and effective fluid collection for analysis.
Implementation Method 1
the elongated body comprises a capillary bore extending in a longitudinal direction thereof and defines a fluid path
Implementation Method 2
A bevel is referred to as a bevelled surface relative the longitudinal axis of the capillary bore
Data Source
AI summary
A microneedle and a chip are disclosed for extraction fluids. The microneedle is provided on a substrate and comprises an elongated body extending from a distal end with a bevel to a proximal end on the substrate along a longitudinal axis. The elongated body comprises a capillary bore extending in a longitudinal direction thereof and defines a fluid path. The proximal end is integrally connected with the substrate and the capillary bore is in fluid communication with a fluid channel of the substrate. The cross-sectional area of the capillary bore in the distal end is larger than the cross-sectional area of the capillary bore in the proximal end.