Funnel Microneedle Arrays for Easier Insertion and Higher Drug Loading
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Solution Overview
Problem
Microneedles face challenges in tissue insertion due to their small size, requiring high application forces and complex applicators, and manufacturing limitations due to small mold cavities and limited material loading capacity, especially for substances with low solubility in water.
Innovation Solution
Incorporating funnel portions into microneedle arrays to facilitate easier tissue penetration and increase substance loading, with methods involving mold filling and drying processes under centrifugation or pressure differentials to enhance manufacturing precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If microneedles are made small in size, then they can precisely target superficial tissue layers and be relatively pain free, but tissue insertion becomes difficult and requires higher application forces
Solution Approach 1:
The microneedles are embedded within a patch matrix structure, where the patch serves as a carrier that protects and positions the microneedles during application. The patch can be applied as a unified unit, with the microneedles nested within the adhesive or flexible matrix, allowing for controlled insertion while maintaining small needle size for painless operation.
Solution Approach 2:
The patch matrix acts as an intermediary between the application force and the microneedles. Instead of applying force directly to individual small microneedles, the force is distributed through the patch matrix, which then transmits it to the microneedles in a controlled manner, reducing the required application force while maintaining effective insertion.
2Object-affected harmful factors
If microneedles are made small in size, then they can precisely target superficial tissue layers, but the amount of material that can be loaded into them is limited
Solution Approach 1:
The microneedles are nested within a larger patch structure that contains additional reservoirs or matrices for substance storage. The patch itself can contain bulk amounts of therapeutic material that are released through or along with the microneedles, effectively nesting multiple levels of substance delivery within the same device.
Solution Approach 2:
Instead of relying solely on the small volume of individual microneedles for substance loading, the invention extends the substance delivery capability to two or three dimensions by incorporating a patch matrix or base layer that can hold substantial amounts of material. This allows substance loading in the lateral dimensions rather than being constrained only to the small needle volume.
3Ease of manufacture
If conventional molding methods are used for microneedle arrays, then manufacturing can be performed with standard equipment, but the process is not simple, fast, highly reproducible or accurate
Solution Approach 1:
The invention combines multiple manufacturing operations into a single integrated process. The microneedles are formed, positioned, and loaded with substances in one continuous manufacturing step using a single mold, eliminating the need for separate operations for needle formation, array assembly, and substance loading. This merging of operations achieves high productivity and reproducibility while using standard molding equipment.
Solution Approach 2:
The mold is pre-configured with all necessary features including microneedle cavities, positioning structures, and substance loading channels before the manufacturing process begins. This preliminary preparation of the mold allows for rapid, reproducible production without requiring complex adjustments or multiple setup steps during actual manufacturing, achieving both simplicity and high productivity.
4Ease of manufacture
If conventional fluid dispensing systems are used for filling microneedle cavities, then manufacturing can be performed with standard equipment, but misalignment and highly variable fill volumes occur
Solution Approach 1:
The invention replaces the mechanical fluid dispensing system with a mold-based forming approach. Instead of using dispensing needles to deposit fluid into microneedle cavities, the mold cavities themselves are designed to receive and form the substance directly into the microneedles during molding. This substitution eliminates alignment issues and volume variability associated with mechanical dispensing while using standard molding equipment.
Solution Approach 2:
The mold cavities are designed as precise negative copies of the desired microneedle structure, including the exact cavity shapes, positions, and volumes needed. This copying approach ensures that each microneedle receives the correct amount of material with high precision, eliminating the variability inherent in conventional dispensing methods while using standard molding technology.
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 funnel design reduces the force required for insertion, increases substance loading capacity, and improves manufacturing accuracy, resulting in higher penetration success rates and efficient delivery of substances.
Implementation Method 1
tissue insertion can be difficult. This results from the elastic nature of the targeted tissue (e.g., skin) because much of the applied force when administering them to skin is used to deform the skin underneath
Implementation Method 2
methods involving mold filling and drying processes under centrifugation or pressure differentials to enhance manufacturing precision
Implementation Method 3
methods involving mold filling and drying processes under centrifugation or pressure differentials
Implementation Method 4
methods involving mold filling and drying processes under centrifugation or pressure differentials to enhance manufacturing precision
Data Source
Figure 1~2
Figure 3A~4C
Figure 5~8
AI summary
A microneedle array is provided for administrating a drug or other substance into a biological tissue. The array includes a base substrate; a primary funnel portion extending from one side of the base substrate; and two or more solid microneedles extending from the primary funnel portion, wherein the two or more microneedles comprise the substance of interest. Methods for making an array of microneedles are also provided. The method may include providing a non-porous and gas-permeable mold having a two or more cavities each of which defines a microneedle; filling the cavities with a fluid material which includes a substance of interest and a liquid vehicle; drying the fluid material to remove at least a portion of the liquid vehicle and form a plurality of microneedles that include the substance of interest, wherein the filling is conducted with a pressure differential applied between opposed surfaces of the mold.