Microneedle Array Back Surface Roughening for Inspection Halation
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Solution Overview
Problem
The visibility of appearance inspections for microneedle arrays is compromised due to halation caused by the gloss of transparent or translucent microneedle arrays during imaging with a light source and camera, making it difficult to inspect needle shapes and foreign matter effectively.
Innovation Solution
A manufacturing method for microneedle arrays that involves controlling the drying rate of the second liquid to form peak and valley portions on the second surface of the sheet portion, using sodium chondroitin sulfate in the second liquid, and containing a drug in the first liquid, which reduces gloss and enhances visibility during inspections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If transparent or translucent microneedle arrays are used, then the aesthetic appearance and patient acceptance are improved, but halation occurs during imaging making inspection difficult
Solution Approach 1:
The invention applies a roughening treatment specifically to the back surface of the microneedle array, while keeping the front surface (with needles) smooth and transparent. This localized modification creates matte portions that scatter light to prevent halation during inspection, while preserving the transparency and aesthetic appearance of the front surface where patients observe the needles.
Solution Approach 2:
The roughened back surface acts as an intermediary layer that modifies light behavior. By creating a matte surface with controlled roughness, it scatters incident light before it reaches the transparent front surface, preventing the formation of halation artifacts during imaging while maintaining the overall transparency of the device.
2Ease of operation
If the sheet portion is made transparent or translucent, then patient observation of needle status is improved, but gloss causes halation during imaging
Solution Approach 1:
The invention creates different surface qualities in different locations: the front surface remains smooth and transparent for patient observation, while the back surface is roughened to create matte portions that prevent halation during imaging. This local differentiation resolves the contradiction between transparency for observation and gloss prevention for imaging.
3Productivity
If drying rate is increased to reduce production time, then productivity is improved, but uniform peak and valley portions cannot be formed on the sheet surface
Solution Approach 1:
The invention optimizes the drying rate parameter to a specific range (5-50 g/hr·m²) that balances production efficiency with surface quality. By controlling the drying rate within this range, the method enables the formation of uniform peak and valley portions on the sheet surface while maintaining acceptable production speed, resolving the contradiction between productivity and manufacturing precision.
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 improves the visibility of appearance inspections by suppressing halation and maintaining a low average transmittance, allowing for clearer imaging of the microneedle array without the need for additives like colorants, thus ensuring effective inspection of needle shapes and foreign matter.
Implementation Method 1
drying is performed at a rate of 50 g/(hr·m2) or less until a concentration of solid contents of the second liquid reaches 80 wt%
Data Source
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AI summary
Provided are a microneedle array capable of improving the visibility of an appearance inspection, and a manufacturing method of the same. A microneedle array is a microneedle array (100) including: a sheet portion (102) having a first surface (102A) and a second surface (102B) which oppose each other; and a plurality of needle portions (112) arranged on the first surface of the sheet portion, in which the second surface of the sheet portion is configured by a rough surface having peak portions (102C) and valley portions (102D), and an average transmittance of the sheet portion in a wavelength range of 300 nm to 740 nm is 75% or less.