Microneedle with Segmented Geometry for High Drug Loading
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Solution Overview
Problem
Existing microneedle technologies face challenges in efficiently and painlessly administering drugs to the epidermal layer of the skin, particularly in supporting large quantities of drugs and achieving satisfactory puncture properties for both liquid and solid formulations.
Innovation Solution
A microneedle design with a top section, shaft section, and base section, featuring a tip apex angle of 15 to 60°, a solid composition containing the drug fixed to the side surface of the shaft section, and specific geometric ratios to ensure effective drug loading and puncture performance, allowing for efficient drug administration without pain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a microneedle is designed with a sharp tip for effective puncture, then puncture property is improved, but the microneedle becomes prone to breaking and bending
Solution Approach 1:
The microneedle is divided into three distinct sections: top section (tip apex angle 15-60° for puncture), shaft section (for drug loading), and base section (larger area for support). This segmentation allows each section to be optimized independently - the top section maintains sharpness for puncture while the base section provides structural support to prevent breaking
Solution Approach 2:
Different sections of the microneedle have different geometric properties tailored to their specific functions. The top section has a sharp tip apex angle of 15-60° optimized for puncture, while the base section has a larger area optimized for structural support. This local optimization resolves the contradiction between sharpness and strength
2Quantity of substance
If the base section area is increased to support more drug, then drug loading capacity is improved, but the overall size of the microneedle increases
Solution Approach 1:
The invention utilizes the lateral surface area of the shaft section (a two-dimensional surface) for drug loading instead of increasing the overall volume. By fixing drug-containing solid composition on the shaft section's lateral surface, the design achieves high drug loading capacity without proportionally increasing the microneedle's volume
3Reliability
If the tip diameter is reduced for better puncture performance, then puncture property is improved, but the microneedle becomes more fragile and harder to manufacture
Solution Approach 1:
The invention specifies an optimized range for the tip apex angle (15-60°) and tip diameter (1-20 μm) that balances puncture performance with manufacturability. This parameter optimization ensures the tip is sharp enough for effective puncture while remaining feasible to manufacture using conventional microneedle fabrication techniques
Data Source
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AI summary
A microneedle and a microneedle array which can support not only a drug but also a stabilizer and a thickener in large quantities and have excellent puncture property. The microneedle is used to administer a drug transdermally and comprises a top section, a shaft section and a base section, wherein (i) the tip apex angle (α) is 15 to 60°; (ii) the tip diameter (D0) is 1 to 20 µm; (iii) the area (A3) of the top surface of the base section is larger than the area (A2) of the bottom surface of the shaft section; (iv) the following expressions (1) and (2) are satisfied H/D4≧3 (H is the overall height, and D4 is the diameter of the bottom surface of the base section) β≧90-0.5α (β is the angle formed between the side surface of the shaft section and the top surface of the base section, and α is the tip apex angle.); and (v) a solid composition containing a drug is fixed to the side surface of the shaft section and the following expression (5) is satisfied. 10°≦γ≦60° (γ is the angle formed by tangent lines connecting the apex of the top section and the surface of the solid composition fixed to the side surface of the shaft section.)