Self-Aligned Electrospray Device Aperture Alignment
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Solution Overview
Problem
Existing microfabricated electrospray devices often suffer from misalignment of apertures and emitters, leading to reduced efficiency or inoperability due to aerosol interception by the device components.
Innovation Solution
A self-aligned electrospray device is fabricated using a silicon wafer with an electrically insulating layer and a conducting layer, where the insulating layer is undercut to promote Taylor cone formation, and the device is manufactured using techniques like Bosch or metal-assisted chemical etching to ensure precise alignment of emitters with extractor apertures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If separate wafers are bonded to form emitters and extractor, then device assembly is possible, but misalignment between apertures and emitters occurs
Solution Approach 1:
The patent merges the emitter and extractor structures into a single integrated device formed from one silicon wafer. The insulating layer is deposited and patterned on the wafer surface, then etched to form both the emitter apertures and extractor apertures in the same wafer, eliminating the need for separate wafer bonding and ensuring precise alignment between corresponding apertures and emitters.
Solution Approach 2:
The insulating layer is deposited and patterned on the silicon wafer surface before the final device fabrication steps. This preliminary action establishes the precise locations of emitter apertures and defines the regions where extractor apertures will be formed, ensuring alignment is built into the structure from the beginning rather than requiring post-fabrication adjustment.
2Ease of manufacture
If conventional fabrication techniques are used, then manufacturing process is simple, but aerosol interception by device components occurs
Solution Approach 1:
The patent introduces a vertical dimension to the device structure by forming an insulating layer with controlled thickness on the silicon wafer surface. This vertical layering creates a three-dimensional structure where the insulating layer thickness and positioning precisely control the gap between emitter and extractor, preventing aerosol interception while maintaining manufacturing simplicity through standard deposition and etching techniques.
Solution Approach 2:
The insulating layer is selectively deposited and patterned only in specific regions where emitters and extractors are formed, rather than uniformly across the entire wafer. This localized approach ensures precise alignment and appropriate spacing only where needed, while leaving other regions of the wafer unaffected and simplifying the overall fabrication 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 self-aligned electrospray device prevents aerosol interception, enhancing operational efficiency and reliability by ensuring precise alignment of emitters with apertures, thereby improving the device's performance and reducing the likelihood of misalignment issues.
Implementation Method 1
Applying an electric potential between the extractor 106 and a conductive fluid 120 in the reservoir 102 causes a Taylor cone 122 to form in the space between the extractor 106 and each emitter 110 so that ions exit each aperture 112 as an aerosol.
Implementation Method 2
Electrosprays are aerosols of charged particles (droplets, or ions) that are electrostatically extracted from an electrically conductive liquid.
Data Source
AI summary
In some embodiments, a self-aligned electrospray device can include a silicon wafer, a fluid reservoir, and a circuit. The silicon wafer can have a layer of electrically insulating material deposited on a top surface and a deposited layer of electrically conducting material. The silicon wafer and the deposited layers can have through holes. The electrically insulating layer may be undercut. The fluid reservoir can be mounted to a bottom surface of the silicon wafer for containing fluid. The circuit can provide an electric potential difference and be coupled between the layer of electrically conducting material and the fluid reservoir.