Hollow Microneedle Manufacturing via Localized Heating and Warp Suppression
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Solution Overview
Problem
Conventional methods for manufacturing fine hollow protruding tools, such as microneedles, face challenges including low productivity, high costs due to expensive molds, and limited flexibility in shape and material choices, as well as difficulties in controlling the distance from the base to the needle's tip end during the manufacturing process.
Innovation Solution
A method involving a protrusion forming step where a projecting mold with a heating means is used to form protrusions from a thermoplastic resin base sheet, utilizing a first warp-suppressing means to prevent warping during insertion, followed by a cooling step and a release step with a second warp-suppressing means to prevent warping during mold withdrawal, allowing for efficient and precise formation of fine hollow protruding tools without the need for extensive heating of the entire resin body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional manufacturing methods using pre-formed molds are used, then hollow microneedles can be manufactured, but the production cost increases and productivity decreases due to expensive molds and complex processes
Solution Approach 1:
The manufacturing process is segmented into distinct stages: heating the base sheet to soften the thermoplastic resin, inserting the projecting mold part into the softened material, cooling to solidify, and withdrawing the mold. This segmentation allows each step to be optimized independently and enables continuous production cycles.
Solution Approach 2:
The invention utilizes parameter changes in the thermoplastic resin material - specifically transitioning between solid and softened states through temperature control. By heating the base sheet to soften the resin locally, the projecting mold can be inserted easily, then cooling solidifies the material to form the hollow protrusion, enabling efficient manufacturing without expensive pre-formed molds.
2Ease of manufacture
If the entire base sheet is heated to form protrusions, then the thermoplastic resin becomes soft enough for mold insertion, but warping occurs reducing manufacturing precision
Solution Approach 1:
Instead of heating the entire base sheet, the invention applies heat locally only to the contact section where the projecting mold part will be inserted. This localized heating softens the thermoplastic resin precisely where needed while keeping the rest of the base sheet cool and dimensionally stable, preventing warping and maintaining manufacturing precision.
Solution Approach 2:
The invention counteracts potential warping by using warp-suppressing means during both the insertion and withdrawal phases. These means pre-compenstate for the forces that would cause warping, ensuring the protrusion maintains its intended shape and position throughout the manufacturing process.
3Productivity
If the projecting mold part is inserted into the softened base sheet, then hollow protrusions are formed, but warping occurs during insertion and withdrawal reducing precision
Solution Approach 1:
The invention employs warp-suppressing means that act in advance and during the critical insertion and withdrawal operations. These means counteract the forces generated during mold insertion and extraction, preventing warping that would otherwise displace the protrusion tip from its intended position and compromising manufacturing precision.
Solution Approach 2:
The base sheet is heated and softened in advance before mold insertion, creating a receptive material state that facilitates easy mold penetration. This preliminary preparation ensures the material is in the optimal state for forming, enabling efficient hollow protrusion creation while maintaining precision through controlled subsequent cooling and solidification.
4Adaptability or versatility
If hollow microneedles are manufactured using traditional methods, then delivery capability is achieved, but the amount of agent delivery is limited by needle shape constraints
Solution Approach 1:
The invention enables versatile agent delivery by allowing the hollow interior volume to be independently controlled from the external needle shape. Through parameter changes in the molding process - such as adjusting mold insertion depth, base sheet thickness, and cooling conditions - the internal cavity volume can be optimized for maximum agent capacity while the external shape remains suitable for skin penetration.
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
This method enhances productivity, reduces costs, and improves precision in manufacturing fine hollow protruding tools by efficiently heating only the necessary sections and using a controlled process to suppress warping, resulting in consistently shaped microneedles with a hollow interior.
Implementation Method 1
while softening, with heat, a contact section in the base sheet where the projecting mold part contacts the base sheet
Implementation Method 2
a base sheet including a thermoplastic resin... while softening, with heat, a contact section in the base sheet
Implementation Method 3
a cooling step of cooling the protrusion in a state where the projecting mold part is inserted in an interior of the protrusion
Data Source
AI summary
Method for manufacturing fine hollow protruding tool by: bringing a projecting mold part with a heating means into contact from one surface side of a base sheet including a thermoplastic resin, and, while heat-softening the contact section, inserting the projecting mold part into the base sheet, to form a protrusion protruding from the other surface side; and, after a cooling step, withdrawing the projecting mold part from the interior of the protrusion, forming the fine hollow protruding tool. In the protrusion forming step, the protrusion is formed by using a first warp-suppressing means that suppresses warping of the base sheet when the projecting mold part is inserted into the base sheet. In the release step, the fine hollow protruding tool is formed by using a second warp-suppressing means that suppresses warping of the base sheet when the projecting mold part is withdrawn from the interior of the protrusion.