Hollow Microneedle Fabrication via Template Coating and Removal
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Solution Overview
Problem
Current methods for fabricating hollow microneedle arrays are hindered by high costs and low throughput, making commercial mass production challenging due to the need for expensive and complex microfabrication techniques, and the inability to reuse molds, which restricts their application in transdermal drug delivery.
Innovation Solution
A method involving coating an elongated template with a second material, removing the template's tip to create an opening, and then removing the template itself to form a hollow microneedle, allowing for mass production using simple and cost-effective techniques without the need for complex equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If modified-LIGA process, deep reactive ion etching, or other microfabrication techniques are used to fabricate hollow microneedles, then manufacturing precision and structural integrity are improved, but device complexity and production cost increase significantly
Solution Approach 1:
The fabrication process is segmented into distinct stages: forming microneedle protrusions on a template, coating only the protrusion surfaces with metal or polymer material, and selectively removing the template. This segmentation allows each stage to be optimized independently, reducing overall process complexity while maintaining precision.
Solution Approach 2:
The microneedle template and support structure are prepared in advance before the actual microneedle formation. By pre-forming the template with precise geometric features and performing preliminary coating steps, the subsequent microneedle fabrication requires simpler processing, reducing device complexity.
2Manufacturing precision
If conventional microfabrication methods are used for hollow microneedle production, then manufacturing precision is improved, but productivity decreases due to low throughput and inability to reuse molds
Solution Approach 1:
The support structure serves multiple functions: it provides mechanical support during fabrication, defines the array pattern, and acts as a reusable mold for mass production. This multi-functionality allows a single support structure to produce multiple microneedle arrays, dramatically increasing productivity while maintaining precision through the structured coating process.
Solution Approach 2:
The template material is designed to be selectively removable after serving its purpose in defining the microneedle geometry. By discarding the temporary template structure and recovering the support structure for reuse, the process achieves both high precision (from the template) and high productivity (from mold reuse).
3Manufacturing precision
If each mold is used only once in hollow microneedle fabrication, then manufacturing precision is maintained, but productivity and cost-effectiveness deteriorate due to inability to reuse molds
Solution Approach 1:
The support structure is designed to be reusable across multiple fabrication cycles. It maintains its geometric precision and structural integrity while serving as a mold for producing multiple microneedle arrays, thereby improving both productivity and cost-effectiveness without sacrificing manufacturing precision.
Solution Approach 2:
The coating process applies material slightly beyond the exact microneedle boundaries, ensuring complete coverage. This excessive action compensates for any minor variations in template geometry or coating uniformity, allowing the reusable mold to maintain precision across multiple uses.
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 enables the efficient and cost-effective mass production of high-quality hollow microneedles, suitable for both laboratory and industrial use, with flexible material options like metals and polymers, facilitating their widespread application in transdermal drug delivery.
Implementation Method 1
coating templates of a first material with a second material using techniques including but not limited to painting, spin-coating, sputtering, pulling, electroless plating, electroplating, physical vapor deposition, chemical vapor deposition, sol-gel, or their combinations
Implementation Method 2
coating templates of a first material with a second material using techniques including but not limited to painting, spin-coating, sputtering, pulling, electroless plating, electroplating, physical vapor deposition, chemical vapor deposition, sol-gel, or their combinations
Implementation Method 3
The original templates of the first material are removed by methods including but not limited to sintering, dissolving, melting, etching, or their combinations
Implementation Method 4
The original templates of the first material are removed by methods including but not limited to sintering, dissolving, melting, etching, or their combinations
Data Source
AI summary
A novel method suitable for commercially mass production of hollow microneedle with high quality for delivery of drugs across or into biological tissue is provided. It typically includes the following processes: (1) coating an elongated template of a first material with a second material to form a cover; (2) removing tips of the template and cover to form an opening in the cover; and (3) removing the template of the first material to obtain hollow microneedles of the second material. This simple, efficient and cost-effective fabrication method can mass produce hollow microneedle arrays involving no complicated and expensive equipments or techniques, which can be used in commercial fabrication of hollow needles for delivering drugs or genes across or into skin or other tissue barriers with advantages of minimal damage, painless, long-term and continuous usages.