Hollow Microneedle Opening Layout for Precise Skin Piercing
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Solution Overview
Problem
Existing methods for manufacturing hollow microneedles with openings face challenges in achieving precise shape and stability, leading to burr formation and difficulty in piercing the skin, due to temperature variations and laser-induced deformations in injection molding and laser drilling processes.
Innovation Solution
A method and apparatus that form fine hollow protrusions with precise shape by inserting a protrusion-forming mold into a thermoplastic resin sheet, followed by contactless opening formation using a laser device from the opposite side, ensuring the opening is offset from the center and avoiding burr formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If injection molding with mold parts is used to manufacture hollow microneedles, then productivity is improved, but manufacturing precision deteriorates due to temperature variations causing burr formation
Solution Approach 1:
The manufacturing process is divided into two separate stages: first forming hollow microneedles using injection molding, then separately forming openings using laser processing. This segmentation allows each process to be optimized independently, preventing the compromise between productivity and precision that occurs when both requirements must be met in a single process.
Solution Approach 2:
The patent introduces an intermediary step where hollow microneedles are first formed without openings, then openings are added separately. This intermediary state (hollow microneedles without openings) allows the first process to focus on shape precision while the second process focuses on opening formation, eliminating the conflict between productivity and precision.
2Manufacturing precision
If laser drilling is used to form openings in hollow microneedles, then manufacturing precision is improved, but the microneedles experience laser-induced deformations affecting stability
Solution Approach 1:
The hollow microneedle structure is formed in advance using injection molding before the opening formation step. This preliminary action creates a stable base structure that can better withstand the subsequent laser processing, reducing laser-induced deformations while maintaining opening precision.
Solution Approach 2:
The manufacturing process uses periodic action by separating the formation of hollow microneedles and the formation of openings into distinct time periods. This allows the microneedle structure to stabilize between processing steps, reducing cumulative thermal effects and deformations from continuous laser exposure.
3Productivity
If openings are formed at the center of microneedle tips, then agent delivery efficiency is improved, but piercing ability deteriorates due to reduced structural strength
Solution Approach 1:
The patent applies asymmetry by positioning openings off-center in the microneedle structure. This asymmetric placement creates an optimized balance where the opening is positioned to maximize agent delivery efficiency while maintaining sufficient structural strength at the tip for effective skin piercing.
Solution Approach 2:
The patent applies local quality by creating different structural characteristics at different locations of the microneedle. The tip region maintains high strength for piercing, while the opening region is strategically positioned and sized to optimize agent delivery, allowing each region to have the quality needed for its specific function.
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 approach enables the production of hollow microneedles with precise shape and structure, allowing for stable agent delivery into the skin without pain, as the microneedles can easily pierce the skin and maintain structural integrity.
Implementation Method 1
inserting a protrusion-forming mold part into a base material sheet from one face side thereof, the base material sheet containing a thermoplastic resin, thereby forming non-penetrated hollow protrusions
Implementation Method 2
forming an opening that penetrates the non-penetrated hollow protrusion by using contactless opening forming means disposed on the other face side of the base material sheet
Data Source
AI summary
A method for manufacturing a hollow protruding implement (1) including a fine hollow protrusion (3) having an opening (3h) of the present invention includes a protrusion forming step of inserting a projecting mold part (11) into a base material sheet (2A) from one face (2D) side thereof, the base material sheet containing a thermoplastic resin, thereby forming a non-penetrated hollow protrusion (3) projecting from another face (2U) side of the base material sheet (2A). Subsequently, an opening forming step is performed in which an opening (3h) that penetrates the hollow protrusion (3) is formed by using a contactless opening forming means disposed on the other face (2U) side of the base material sheet (2A).