Microneedle Array Depth Control via Segmented Protrusion Heights
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Solution Overview
Problem
Existing microneedle devices for transdermal medicament delivery face challenges in controlling skin penetration depth to minimize pain while maintaining production simplicity and cost-effectiveness, particularly in forming hollow microneedles with accurate medicament discharge openings.
Innovation Solution
A microprotrusion device with a combination of needle-like first protrusion portions and hollow second protrusion portions of varying heights, where the second protrusions act as depth limiters, allowing controlled skin penetration and stable, low-cost production through a simultaneous pressing method using projection molds with different heights.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If solid-type microneedles with uniform height are used for transdermal medicament delivery, then the medicament can be applied to the entire surface of each microneedle, but the skin penetration depth cannot be controlled to minimize pain
Solution Approach 1:
The microneedle array is segmented into two distinct types: first microneedles with greater height for skin penetration and medicament delivery, and second microneedles with lesser height that do not penetrate the skin. This segmentation allows different functional zones within the same device, enabling painless operation by preventing unnecessary deep penetration while maintaining medicament delivery capability.
Solution Approach 2:
Different regions of the microneedle array are assigned different properties: the first microneedles are designed with sufficient height and hollow structure for effective medicament discharge into the skin, while the second microneedles are designed with reduced height to act as depth limiters. This local differentiation of properties enables controlled penetration depth and reduces pain without compromising the medicament delivery function.
2Manufacturing precision
If hollow microneedles are produced with accurate medicament discharge openings, then transdermal medicament delivery is improved, but production complexity and cost increase
Solution Approach 1:
The hollow structures and opening portions are formed during the initial molding process rather than requiring subsequent complex processing steps. By incorporating the hollow cavity formation and opening creation into the primary injection molding operation, the patent achieves high manufacturing precision for the microneedle structures while maintaining ease of manufacture through process integration.
Solution Approach 2:
The patent replaces complex mechanical post-processing methods (such as drilling, punching, or laser cutting) with a streamlined injection molding process that directly forms the hollow structures and openings. This substitution of manufacturing methodology reduces production complexity and cost while maintaining the required precision for medicament discharge functionality.
3Productivity
If all microneedles pierce the skin to enable medicament injection, then medicament delivery is maximized, but pain and tissue damage increase
Solution Approach 1:
The microneedle population is divided into two functional segments: first microneedles responsible for skin penetration and medicament delivery, and second microneedles that serve as depth limiters and do not penetrate the skin. This segmentation ensures that only the necessary number and type of microneedles pierce the skin, maximizing medicament delivery efficiency while minimizing pain and tissue damage by preventing unnecessary penetration events.
Solution Approach 2:
The second microneedles with lesser height are positioned to act in advance as depth limiters, preventing the microneedles from penetrating deeper than intended. This preliminary anti-action counteracts the potential harmful effect of excessive penetration depth before it occurs, thereby reducing pain and tissue damage while allowing the first microneedles to perform their medicament delivery function effectively.
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 device enables precise control of skin penetration depth, reducing pain during transdermal medicament delivery and facilitating the production of high-quality microneedles with accurate medicament discharge, thus overcoming the limitations of existing technologies.
Implementation Method 1
a substrate sheet that can be softened through the application of heat
Implementation Method 2
heating the abutment portion, during which the first projection mold is pressed toward the one surface side of the substrate sheet by a predetermined distance so as to deform the pressed portion of the substrate sheet
Data Source
AI summary
A microprotrusion device (1A) according to the present invention includes a needle-like and hollow first protrusion portion (3) that is formed so as to protrude from one surface (2a) of a substrate sheet (2) and a hollow second protrusion portion (4) that is formed so as to protrude from a vicinity of the first protrusion portion (3) on the one surface (2a) of the substrate sheet (2) and has a protrusion height lower than that of the first protrusion portion (3). The first protrusion portion (3) has an opening at its tip end portion, and a hollow portion (30) of the first protrusion portion (3) is in communication with the outside via the opening portion (31). The opening portion (31) is formed at the tip end of the first protrusion portion (3).