Microfluidic Spray Device With Offset Nozzle for 1 μm Droplets
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Solution Overview
Problem
Current microfluidic devices are unable to produce small droplets of 1 μm diameter, which are required for nebulizers, due to limitations in nozzle size achievable with existing photolithographic technology.
Innovation Solution
The microfluidic device incorporates a drop emission channel with a nozzle that is partially offset, forming an intersection with the fluid containment chamber, reducing the effective cross-sectional area to produce smaller droplets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photolithographic technology is used to manufacture nozzles, then manufacturing precision is limited to current technological capabilities, but device complexity and manufacturing difficulty increase when attempting to produce smaller droplets
Solution Approach 1:
The invention transitions from planar photolithographic patterning to three-dimensional self-aligned stacking. By forming the first and second nozzles in different layers (vertical dimension) and offsetting their horizontal positions, the effective opening is reduced without requiring higher precision in a single layer. This dimensional approach allows current photolithography tools to achieve smaller effective nozzle openings.
Solution Approach 2:
The single nozzle function is segmented into two separate nozzles (first nozzle and second nozzle) positioned at different locations and orientations. Each nozzle is manufacturable with current technology, but their combined offset arrangement creates the effective small opening needed for 1 μm droplets, avoiding the need to manufacture a single ultra-precise small nozzle.
2Length of moving object
If nozzle size is reduced to produce smaller droplets, then droplet diameter decreases to achieve nebulizer requirements, but manufacturing precision requirements exceed current photolithographic capabilities
Solution Approach 1:
The invention uses vertical layering to achieve horizontal positioning effects. The first nozzle is formed in a lower layer and the second nozzle in an upper layer, offset horizontally. This 3D arrangement allows the effective opening (distance between nozzle centers) to be smaller than what single-layer photolithography could achieve, enabling 1 μm droplet production with current manufacturing tools.
Solution Approach 2:
The solution nests multiple nozzle structures within a single device body at different vertical levels. The first nozzle and second nozzle are nested in separate layers, with their offset positions creating the effective small opening. This nested multi-layer structure allows complex geometric relationships to be achieved through sequential layer formation rather than single-step high-precision patterning.
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 design allows for the production of droplets smaller than achievable with current manufacturing techniques, enhancing the density and efficiency of droplet generation.
Implementation Method 1
The microfluidic device 30 of FIG. 3 comprises... A piezoelectric actuator 39 is arranged over the membrane 37, in the actuator chamber 35
Implementation Method 2
A heater 20 is provided within the thin layer 13... The heater 20 may have an area of approximately 40×40 μm2 and generate, for example, an energy of 3.5 μJ, and is able to reach a maximum temperature of 450° C. in 2 μs
Implementation Method 3
This temperature is chosen, on the basis of the liquid used, to allow the liquid to instantaneously reach the boiling point, for example at a temperature close to 300° C. In this situation, the pressure increases to a high level, for example approximately 5 atm, forming a vapor bubble 17, which disappears after a few microseconds
Data Source
AI summary
A microfluidic device provided in a body accommodating a fluid containment chamber. A fluidic access channel and a drop emission channel are formed in the body and are in fluidic connection with the fluid containment chamber to form a fluidic path towards the body outside through a nozzle having an outlet section. An actuator is operatively coupled to the fluid containment chamber and is configured to cause ejection of fluid drops through the drop emission channel in an operating condition of the microfluidic device. The drop emission channel comprises a portion of reduced section having a smaller area than the outlet section of the nozzle.