In-Plane Metal Microneedle Arrays for Buckling-Resistant Skin Insertion
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Solution Overview
Problem
Manufacturing high aspect ratio sampling microneedles is challenging due to processing difficulties and high costs, and existing methods fail to prevent buckling or breakage during insertion into the skin.
Innovation Solution
A method involving the use of medical stainless steel or titanium alloy metal sheets, processed into high aspect ratio in-plane metal microneedle arrays using a clamping tooling and wire cutting, with an equal-strength design and an inserting auxiliary device to prevent buckling, allowing for batch production and efficient use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional microneedle processing technologies (photolithography, deep reactive ion etching, X-ray lithography) are used, then microneedles can be manufactured, but they cannot process high aspect ratio microneedles due to processing difficulties
Solution Approach 1:
The patent changes the manufacturing approach from top-down etching to bottom-up drawing, fundamentally altering the process parameters. The drawing head with micron-level microcolumns draws molten SU-8 glue into columnar structures with controllable height, enabling high aspect ratios (up to 2mm length) that were previously unachievable with conventional lithography methods
Solution Approach 2:
The patent introduces polymer drawing molding as an intermediary process between material deposition and final metal microneedle formation. The SU-8 polymer columns serve as temporary molds that are later coated with metal and dissolved, leaving behind high aspect ratio metal microneedles that cannot be directly formed by conventional methods
2Length of moving object
If polymer drawing molding with metal plating is used to manufacture high aspect ratio microneedles, then microneedles with length of 2 mm can be successfully manufactured, but the manufacturing technology is relatively complicated, high in cost and difficult to realize batch production
Solution Approach 1:
The patent merges multiple separate processes (polymer drawing, metal plating, polymer dissolution) into an integrated batch production system. Multiple metal sheets are stacked and clamped together, allowing simultaneous processing of many microneedles in one operation, thereby simplifying the overall manufacturing technology and enabling batch production
Solution Approach 2:
The patent segments the manufacturing process into distinct modular stages: (1) stacking and clamping multiple metal sheets, (2) wire cutting to form microneedle patterns, (3) releasing and collecting microneedles. This segmentation allows each stage to be optimized independently and facilitates batch production while maintaining simplicity
3Length of moving object
If high aspect ratio columnar microneedles are manufactured, then sampling depth is improved, but the long and thin size is easy to induce buckling or breakage during insertion into the skin
Solution Approach 1:
The patent applies local quality by creating non-uniform cross-sectional areas along the microneedle length. The microneedles have larger cross-sections at the base and progressively smaller cross-sections toward the tip, concentrating material where structural support is most needed. This gradient structure provides optimal buckling resistance for the required sampling depth while maintaining sharp tips for penetration
Solution Approach 2:
The patent uses composite material structure by combining multiple thin metal sheets (20-200 microns each) stacked together. This layered composite approach provides enhanced structural integrity and buckling resistance compared to solid microneedles of the same outer dimensions, while still achieving the required high aspect ratio and sampling depth
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 method simplifies processing, reduces costs, and enhances the reliability and accuracy of high aspect ratio microneedle arrays, preventing buckling and ensuring effective insertion into the skin.
Implementation Method 1
clamping the metal sheets and the tooling encapsulated in step 4 to a wire cutting device, determining a wire path according to the geometry and sizes of the sheet plane metal microneedles designed in step 5 by the wire cutting device, conducting wire cutting on the tooling and the metal sheets 5 as a whole
Data Source
AI summary
A high aspect ratio in-plane metal microneedle array, a manufacturing method and a clamping and inserting auxiliary device thereof is disclosed. A large-size metal sheet is cut into small metal sheets. A clamping tooling composed of two upper and lower metal cover plates is processed. Inner sides of the upper and the lower cover plates of the tooling are provided with grooves in which the metal sheets are placed and fastened by bolts. Wire cutting is conducted on the tooling and the metal sheets as a whole to obtain a plane metal microneedle array with a plurality of microneedle bodies. In addition, an assembling and clamping device and an inserting auxiliary device of the high aspect ratio in-plane metal microneedle array is provided. The assembled inserting auxiliary device is placed on skin, and the microneedle array is inserted into the skin through the auxiliary device.