Multilayer Microneedle Array Using PMMA and Polycarbonate
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The manufacturing of microneedle arrays faces challenges in producing microneedles with high aspect ratios for sharp tips and a combination of mechanical and chemical properties necessary for different phases of use, such as penetration, structural integrity, and chemical resistance, while existing methods like injection molding often result in poor replication and failure to fill high-aspect-ratio molds.
Innovation Solution
A microneedle array is formed using a multilayer polymer sheet composed of polymethylmethacrylate (PMMA) and polycarbonate (PC) layers, where PMMA provides geometric replication accuracy and hardness, and PC offers toughness and durability, utilizing a hot embossing technique to achieve good tip replication and structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If injection molding is used to manufacture microneedle arrays, then production efficiency is improved, but tip replication accuracy deteriorates due to failure to fill high-aspect-ratio molds
Solution Approach 1:
The patent changes the material parameter by switching from conventional polymers to wax-based materials that exhibit specific rheological properties during molding. The wax material's ability to flow and fill high-aspect-ratio molds while maintaining shape fidelity resolves the contradiction between production efficiency and tip replication accuracy
Solution Approach 2:
The patent utilizes phase transition of wax materials during the molding process. The material transitions from solid to liquid state during injection, enabling complete mold filling, then transitions back to solid state to maintain the precise microneedle tip geometry, thereby achieving both high productivity and manufacturing precision
2Shape
If microneedles are made with high aspect ratio for sharp tips, then penetration capability is improved, but structural integrity deteriorates due to increased brittleness
Solution Approach 1:
The patent employs composite material construction with a wax-based outer layer providing sharp tip geometry and an inner core material providing structural support. This composite structure enables the microneedles to maintain both high aspect ratio for sharpness and sufficient structural integrity to prevent breakage during handling and insertion
3Reliability
If microneedles are made with high hardness for chemical resistance, then chemical stability is improved, but mechanical durability deteriorates due to increased brittleness
Solution Approach 1:
The patent applies local quality differentiation by using wax-based materials specifically at the microneedle tip and surface regions where chemical resistance is most critical, while the inner core uses materials optimized for mechanical durability. This localized material assignment allows the structure to simultaneously achieve chemical stability and mechanical toughness without compromising either property
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 multilayer polymer microneedle arrays achieve sharp tips for pain-free penetration, maintain structural integrity, and exhibit chemical resistance, enabling efficient and cost-effective mass production with improved mechanical performance and regulatory compliance.
Implementation Method 1
A temperature of at least a portion of the multilayer polymer in contact with the tool is above a glass transition temperature of the multilayer polymer
Implementation Method 2
pressurizing at least a portion of the multilayer polymer between the pressing device and the tool such that the multilayer polymer flows into the cavities
Data Source
Figure 1A~1B
Figure 2A~4
Figure 5
AI summary
This disclosure describes an array (114) of microneedles (140) formed from a multilayer sheet (110), such as a co-extruded multilayer film, having a first layer (118) (e.g., a top layer) of polymethylmethacrylate (PMMA) and a second layer (122) (e.g. a bottom layer) of polycarbonate (PC). For example, the microneedle array is formed from the multilayer sheet using a process, such a hot embossing process, such that the first layer of PMMA (of the multilayer sheet) forms a plurality of microneedles (e.g., spikes) of the microneedle array and the second layer of PC (of the multiplayer sheet) provides toughness for the microneedle array. This disclosure also includes methods (e.g., extrusion methods and/or embossing methods) and systems for manufacturing the array of microneedles, as well as articles of manufacture, such as microneedles, formed by such methods and systems.