Microstructure Mold Channels for Uniform Microneedle Drying
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Solution Overview
Problem
Existing methods for manufacturing microneedle arrays face issues with uneven distribution of liquid formulations due to hydrophobic properties in casting molds, leading to product defects like cavities and brittleness, requiring complex post-treatments and high scrap rates.
Innovation Solution
A mold element with channels and optionally bars on its surface, designed to improve material distribution and drying uniformity, ensuring even application and reducing internal stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If aqueous liquid is applied across the entire surface of a hydrophobic casting mold, then the liquid should cover the surface, but the liquid is not evenly distributed and may not reach all depressions
Solution Approach 1:
The casting mold surface is segmented into multiple regions with channels dividing the liquid application area. This segmentation allows the liquid to be distributed through multiple pathways rather than relying on uniform spreading across the entire hydrophobic surface, ensuring better penetration into depressions.
Solution Approach 2:
Channels act as intermediary structures between the liquid source and the depressions. These channels guide and direct the liquid flow, overcoming the hydrophobic barrier by providing defined pathways that force liquid distribution into areas that would otherwise be inaccessible.
2Productivity
If the applied liquid dries completely, then the product is formed, but cavities occur during drying and internal stresses increase brittleness
Solution Approach 1:
Channels are pre-formed in the casting mold to establish controlled drying pathways before the drying process begins. These channels ensure that drying occurs uniformly from multiple directions, preventing cavity formation and stress concentration that would occur with uncontrolled drying.
Solution Approach 2:
The drying process is made non-uniform in a controlled manner through the channel structure. Different regions of the liquid formulation dry at different rates through the channels, creating localized drying gradients that prevent sudden stress buildup and cavity formation while maintaining overall product quality.
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
Enhances the quality and reduces scrap rates by ensuring uniform material distribution and minimizing internal stresses during the drying process.
Implementation Method 1
channels are provided on the upper side of the base body, which open towards the upper side and are connected to the depressions
Implementation Method 2
there is the problem that the applied liquid, which is either an aqueous or other solvent, must dry. During the drying process and the associated volume reduction, cavities may occur
Data Source
AI summary
A mold element, in particular a casting mold for manufacturing microstructures, in particular microneedle arrays, includes a base body. On an upper side of the base body, several depressions for receiving material for manufacturing the microstructure are provided. In order to improve the quality of the microstructure to be manufactured, in particular during a drying process, channels are provided on the upper side of the base body, each of which is connected to at least one of the depressions.