Nebulizer Aperture Plate Manufacturing via Electroplating
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Solution Overview
Problem
Current aperture plate manufacturing methods, such as electroplating, face challenges in controlling hole size and number per unit area, leading to inconsistent particle sizes and output rates, with increased output rate often requiring larger particle sizes, which is undesirable for efficient pulmonary drug delivery.
Innovation Solution
A method involving multiple cycles of masking and electroplating on a conductive mandrel, with each cycle adjusting the wafer thickness and hole configuration to achieve desired flow rates and mechanical properties, allowing for a greater number of holes per unit area and independent control of particle size and flow rate, using materials like Ni and Pd for anti-corrosion and Ag/Cu for anti-bacterial properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If electroplating is used to manufacture aperture plates, then the production process is technically and economically advantageous, but the hole size control becomes difficult leading to inconsistent particle sizes and output rates
Solution Approach 1:
The patent applies preliminary action by first forming a mandrel with precisely defined hole geometry through photolithography and electroforming before the final electroplating process. This pre-established geometric framework ensures that the aperture holes maintain consistent dimensions throughout manufacturing, resolving the hole size control issue while preserving electroplating's manufacturing advantages
Solution Approach 2:
The manufacturing process is segmented into distinct stages: mandrel preparation with precise hole patterns, followed by electroplating of the wafer material. This segmentation allows the hole geometry to be established in the mandrel phase with high precision, while the electroplating phase focuses on building the wafer structure, thereby separating the precision requirement from the manufacturing process
2Productivity
If the number of holes per unit area is increased to improve output rate, then more holes can be packed in, but the holes may become too small or blocked
Solution Approach 1:
By pre-forming the mandrel with the exact hole pattern and dimensions required, the system can accommodate a high density of holes per unit area without compromising hole size. The mandrel acts as a precision template that guides the electroplating process, ensuring that even as hole density increases, each hole maintains its intended geometry and remains patent
Solution Approach 2:
The patent utilizes parameter changes in the electroplating process, specifically controlling plating time and thickness, to achieve the desired wafer thickness while maintaining consistent hole dimensions. By carefully adjusting these parameters, the system can produce wafers with high hole density while preventing hole closure or blockage
3Manufacturing precision
If plating time and wafer thickness are used to control hole size, then the process becomes difficult to control, but alternative methods are needed
Solution Approach 1:
The mandrel is prepared in advance with the precise hole geometry already established through photolithography and electroforming. This preliminary action transfers the complexity of precision hole formation to the mandrel fabrication stage, where it can be controlled through well-established semiconductor manufacturing techniques, rather than attempting to control hole size during the electroplating process itself
4Productivity
If output rate is increased by increasing particle size, then more material can be delivered, but smaller particle size is required for deep lung delivery
Solution Approach 1:
The aperture plate is segmented into multiple small holes rather than a few large openings. This segmentation allows the total open area (controlling output rate) to be increased while keeping individual hole sizes small (controlling particle size). The electroplating process builds sufficient wafer thickness to maintain structural integrity while accommodating this high-density hole pattern
Solution Approach 2:
The patent resolves the contradiction by moving from controlling output rate through individual hole size to controlling it through the number of holes (a different dimensional approach). By increasing the count of small holes rather than enlarging them, the system achieves higher output rates while maintaining the small particle size necessary for deep lung delivery
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 enables a twenty-fold increase in holes per unit area, achieving smaller, more accurate hole sizes and independent control of particle size and flow rate, matching existing nebulizer frequencies and allowing for higher flow rates without increasing particle size, thus enhancing aerosol delivery efficiency.
Implementation Method 1
typically supported around their rims by a vibrating support which is vibrated by a piezo element
Implementation Method 2
a wafer material is built onto a mandrel by a process of electro-deposition where the liquefied metals in the plating bath (typically Palladium and Nickel) are transferred from the liquid form to the solid form on the wafer
Data Source
AI summary
A photo-resist (21) is applied in a pattern or vertical columns having the dimensions of holes or pores of the aperture plate to be produced. This mask pattern provides the apertures which define the aerosol particle size, having up to 2500 holes per square mm. There is electro-deposition of metal (22) into the spaces around the columns (21). There is further application of a second photo-resist mask (25) of much larger (wider and taller) columns, encompassing the area of a number of first columns (21). The hole diameter in the second plating layer is chosen according to a desired flow rate.