Microneedle Unit Rigid Plate Adhesion Skin Contraction
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Solution Overview
Problem
Microneedles often detach from the skin after being pierced due to skin elasticity causing the skin surface to contract back, leading to the microneedle being pushed out.
Innovation Solution
A microneedle unit with a flexible microneedle and a support section that includes an adhesive section and a rigid section with a rigid plate, where the rigid plate has higher rigidity than the adhesive and microneedle, and extends only partially over the microneedle, to reduce skin contraction and prevent detachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the microneedle is pressed against the skin to penetrate through, then the microneedle can pierce the stratum corneum, but the skin elasticity causes the skin surface to contract and push the microneedle out, leading to detachment
Solution Approach 1:
The adhesive section is applied to the skin surface before the microneedle penetration is completed, creating a preliminary bond that holds the microneedle in place. The adhesive section extends beyond the microneedle base to provide additional anchoring on the skin surface, preventing detachment when the skin contracts after stretching.
2Reliability
If the adhesive section covers the entire microneedle base, then adhesion to skin is maximized, but the device complexity and material usage increase
Solution Approach 1:
The adhesive section extends partially beyond the microneedle base in plan view, providing sufficient adhesion to prevent detachment while avoiding excessive material usage. The extension distance is optimized to be just enough to anchor the microneedle securely without requiring complete coverage of the entire microneedle base.
3Strength
If the rigid plate covers the entire microneedle, then structural support is maximized, but the flexibility of the microneedle unit decreases
Solution Approach 1:
The rigid plate overlaps only part of the microneedle in plan view, providing sufficient structural support to maintain the microneedle's position and prevent detachment, while leaving portions of the microneedle and support section flexible to adapt to skin contours and movement.
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 microneedle unit effectively prevents detachment by applying a restoring force to the skin, reducing skin contraction speed and maintaining the microneedle's adherence to the skin.
Implementation Method 1
an adhesive section which extends outside from the second surface in plan view of the second surface, and has adhesiveness to adhere to a skin
Implementation Method 2
a rigid section bonded to the adhesive section, the rigid section including a rigid plate having a rigidity higher than the rigidity of the adhesive section and higher than the rigidity of the microneedle
Implementation Method 3
The projection is configured to penetrate through the stratum corneum, which is a barrier layer of the skin
Data Source
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AI summary
A microneedle unit includes: a microneedle which includes a first surface having at least one projection and a second surface located opposite the first surface, and has flexibility; and a support section that is bonded to the second surface of the microneedle to supports the microneedle. The support section includes: an adhesive section which extends outside from the second surface, and has adhesiveness to adhere to a skin; and a rigid section which includes a rigid plate having a rigidity higher than the rigidity of the adhesive section and higher than the rigidity of the microneedle.