Pyramidal Microneedles with Chamfered Bases for Drug Loading
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Solution Overview
Problem
Microneedle technology faces limitations in drug loading capacity and delivery precision due to the small surface and volume of microneedles, leading to drug waste and variable delivery, with existing methods like centrifugation only slightly increasing loading capacity and being impractical for mass production.
Innovation Solution
The use of pyramidal microneedles with chamfered bases that extend to neighboring bases to increase the base area, combined with a centrifugation process to sediment drug particles directly into the microneedle cavities, and a controlled environment for drying, enhances drug loading capacity and precision by maximizing the area ratio of microneedle cavities to the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the size of microneedles is increased to increase drug loading capacity, then the drug loading capacity is improved, but the pain caused by microneedles increases and dissolution rate decreases
Solution Approach 1:
The microneedle array is divided into multiple individual microneedles with foot-to-foot configuration, where each microneedle is a separate functional unit. This segmentation allows the total drug loading capacity to be distributed across many small needles rather than requiring fewer large needles, thus maintaining low pain and high dissolution rate while achieving high overall drug loading capacity through increased number of microneedles
Solution Approach 2:
The invention transitions from increasing drug loading capacity through increasing individual microneedle size (one dimension) to increasing capacity through increasing the number of microneedles (another dimension - array density). The foot-to-foot configuration maximizes the number of microneedles per unit area, effectively using dimensional transition to resolve the contradiction between individual needle size and total loading capacity
2Quantity of substance
If the number of microneedles is increased to increase drug loading capacity, then the drug loading capacity is improved, but the patch size increases causing ineffective skin penetration and variable drug delivery
Solution Approach 1:
The microneedles are configured in a foot-to-foot arrangement where each microneedle maintains its local geometric properties and penetration characteristics. This local quality consistency ensures that each microneedle penetrates skin effectively and delivers drug precisely, while the collective array achieves high total drug loading capacity. The uniform local structure prevents the precision degradation that would occur with larger patch sizes
3Manufacturing precision
If centrifugation is used to sediment drug particles into microneedle cavities, then delivery precision is improved, but drug loading capacity only slightly increases because majority of drug lands on the substrate
Solution Approach 1:
The invention extracts the substrate area between microneedles by implementing foot-to-foot configuration, effectively removing the space where drug would otherwise sediment uselessly. This extraction ensures that centrifugation forces direct all sedimented drug particles into microneedle cavities rather than allowing them to land on substrate, thereby simultaneously achieving high delivery precision and high drug loading capacity
Solution Approach 2:
The microneedle array is pre-configured in foot-to-foot arrangement before drug loading, creating predetermined drug collection zones at each microneedle base. This preliminary structural preparation ensures that when centrifugation is applied, drug particles have pre-designated destinations (the microneedle cavities) and cannot land on substrate, thereby maximizing both precision and loading capacity from the outset
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 approach significantly increases drug loading capacity and precision, minimizing drug wastage and improving delivery efficiency by ensuring that sedimented drugs are collected within the microneedles, validated through experiments with diclofenac sodium microneedle patches.
Implementation Method 1
employ centrifugal force to sediment the suspended insoluble particles to the bottom of the microneedle template
Implementation Method 2
centrifugation concentrated the drug at the tips of microneedles
Data Source
AI summary
The present invention provides a solution to increase the drug loading capacity and drug delivery precision of dissolving microneedles. These solutions include: (a) increasing the base of the microneedle cavities without substantially changing the microneedle's height and geometry, (b) use of drug suspension and sedimentation of drug by centrifugation, and (c) a specific centrifugation order for filling drug and matrix material. In the first preferred embodiment, a microneedle master mould comprising a plurality of pyramidal microneedles (5100), wherein each of the pyramidal microneedles further comprising a chamfered base (5200) which extends to and adjoins with its neighbouring chamfered bases is provided. In the second preferred embodiment, a method of making dissolving microneedles is provided, comprising (a) providing a microneedle template comprising a plurality of pyramidal microneedle cavities, wherein each of the pyramidal microneedle cavities further comprising a chamfered base which extends to and adjoins with its neighbouring chamfered bases; (b) loading a drug suspension in the substrate cavity on the microneedle template; (c) centrifuging the microneedle template which is loaded with a drug suspension, (d) loading a matrix material solution in the substrate cavity on the microneedle template; (d) centrifuging the microneedle template loaded with the drug suspension and the matrix material solution; and (e) drying the centrifuged microneedle template in a controlled environment.