Monocrystalline Silicon Microneedle Anisotropic Etching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing microneedle technologies face challenges in producing sharp, painless, and minimally damaging transdermal delivery systems due to uneven circumference and limited length and sharpness, leading to skin trauma and inefficiencies in drug delivery, particularly on softer skin types.
Innovation Solution
The development of microneedles with tips formed by slowly etching crystal planes of monocrystalline material, achieving atomic sharpness and minimal friction, and anisotropic wet-etching for production, allowing for sharper tips and reduced skin damage, along with the use of in-plane microneedle arrays for deeper penetration and efficient drug delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional etching processes are used to produce microneedles, then the production process is simple, but the circumference of the needles becomes uneven causing skin damage
Solution Approach 1:
The patent changes the etching parameters by switching from isotropic to anisotropic etching, and further to selective anisotropic etching. This parameter change allows the etching process to proceed in a controlled manner that preserves the circular shape of the needle circumference while maintaining production simplicity. The selective etching of specific crystal planes achieves uniform circumference without complicating the manufacturing process.
2Ease of manufacture
If the microneedle length and sharpness are limited by the production process, then the production is easier, but not all needles penetrate the skin effectively
Solution Approach 1:
The patent applies parameter changes by optimizing the etching depth and angle parameters to achieve the desired needle length and sharpness. By controlling the etching parameters, the process produces needles with sufficient length and sharpness for reliable skin penetration while maintaining ease of manufacture. The selective anisotropic etching allows precise control over needle geometry.
Solution Approach 2:
The patent replaces mechanical sharpening or length adjustment methods with a chemical etching process that directly forms the needle geometry. This substitution eliminates the need for subsequent mechanical processing steps, maintaining production ease while achieving reliable needle penetration characteristics through controlled chemical etching.
3Ease of manufacture
If the tip transition from shaft is abrupt, then the manufacturing is simpler, but the skin is damaged during penetration
Solution Approach 1:
The patent changes the geometric parameters of the needle tip by controlling the etching angle and depth. This creates a gradual transition from the shaft to the tip rather than an abrupt change. The controlled etching parameters produce a smooth geometry that reduces skin damage during penetration while maintaining manufacturing simplicity through a single etching process.
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 solution results in microneedles that require less force for penetration, minimize skin damage, and enable efficient transdermal drug delivery, particularly suitable for softer skin areas, with the ability to form arbitrary two-dimensional arrays for enhanced delivery efficacy.
Implementation Method 1
The tip is formed by slowly etching crystal planes of the monocrystalline material... anisotropic wet-etching for production
Data Source
Figure 1A~2B
Figure 3A~3C
Figure 4A~4B
AI summary
The present invention provides a microneedle, comprising a shaft of a monocrystalline material having at least three walls which are formed by a crystal plane of the monocrystalline material; and a tip connected to an end of the shaft comprising at least three walls which are formed by a crystal plane of the material. The material is preferably silicon. Two of the walls of the tip are formed by the same crystal planes as two walls of the shaft. These two walls are formed by a <111 > crystal plane. Preferably, three walls of the tip are formed by a <111 > crystal plane.