Biodegradable Microneedle Two-Step Structure Strength
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Solution Overview
Problem
Conventional microneedles lack structural strength, limiting their shape and functionality, particularly when contacting human skin, due to restricted angle ranges which restrict their design and application.
Innovation Solution
A biodegradable microneedle structure featuring a two-step design with a first step portion connected to a base and a second step portion taperedly extending, providing a corner angle of 65-100 degrees, which enhances structural strength and allows for broader application without deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the microneedle tip angle is limited to 15-60 degrees to prevent deformation, then structural stability is improved, but design flexibility and application versatility deteriorate
Solution Approach 1:
The microneedle is divided into multiple segments including a shaft portion and a tip portion with different geometric characteristics. The shaft portion has a first cross-sectional shape while the tip portion has a second cross-sectional shape, allowing each segment to be optimized independently for structural stability and functional performance
Solution Approach 2:
Different portions of the microneedle are given different local geometric properties. The shaft portion maintains a specific cross-sectional shape for structural integrity, while the tip portion has a different cross-sectional shape optimized for skin penetration and reduced deformation, with the tip angle specifically controlled within 65-100 degrees
2Ease of manufacture
If the microneedle uses a simple cylindrical shape for ease of manufacture, then manufacturing simplicity is improved, but structural strength and torque resistance deteriorate
Solution Approach 1:
The microneedle structure is segmented into a shaft portion and a tip portion, each with distinct cross-sectional geometries. This segmentation allows the shaft to be manufactured with a shape optimized for strength and torque resistance, while the tip portion can be separately optimized for penetration function
Solution Approach 2:
The microneedle employs asymmetric cross-sectional shapes rather than simple cylindrical symmetry. The shaft portion has a first cross-sectional shape that provides enhanced structural strength and torque resistance, while the tip portion has a second cross-sectional shape optimized for skin interaction
3Ease of operation
If the microneedle has a high aspect ratio for better skin penetration, then penetration effectiveness is improved, but structural strength and resistance to deformation deteriorate
Solution Approach 1:
Different portions of the microneedle are given different local geometric properties to simultaneously achieve high aspect ratio for penetration and sufficient structural strength. The shaft portion has optimized cross-sectional geometry for strength, while the tip portion geometry optimizes penetration, with the overall design maintaining an aspect ratio between 1.2-2.2
Solution Approach 2:
The invention moves beyond simple dimensional scaling by introducing cross-sectional shape variations along the microneedle length. Rather than merely changing length or diameter, the cross-sectional geometry is varied between the shaft and tip portions, adding a dimensional complexity that simultaneously addresses both penetration and strength requirements
Data Source
AI summary
A microneedle structure and a biodegradable microneedle thereof are provided. The biodegradable microneedle defining a central axis includes a first step portion and a second step portion that is taperedly extending from the first step portion along the central axis. The biodegradable microneedle has a total height along the central axis and a maximum internal diameter along a direction perpendicular to the central axis. The total height is within a range of 380-430 μm, and an aspect ratio defined by the total height divided by the maximum internal diameter is within a range of 1.2-2.2. In a cross section of the biodegradable microneedle having the central axis, a part of the second step portion arranged away from the first step portion having a corner. The corner has an angle within a range of 65-100 degrees and faces toward the first step portion.