Nanotextured Electrospray Emitter for Stable Pure Ionic Emission
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Solution Overview
Problem
Existing electrospray emitters face challenges in achieving a pure ionic regime due to high fluidic impedance, clogging issues, and mechanical degradation, particularly in externally wetted types, which lack control over hydraulic impedance and mechanical strength.
Innovation Solution
A method for manufacturing an emitter with a nanotexturized surface using a substrate with protrusions covered by a suspension of particles, followed by etching to form perpendicular nanowires, controlling parameters like density and aspect ratio to minimize onset voltage and maintain a pure ionic regime while enhancing mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If externally wetted emitters are used to achieve passive liquid feeding, then the complexity of the liquid delivery system is reduced, but the control over hydraulic impedance is lost and clogging issues increase
Solution Approach 1:
The emitter incorporates a porous layer with controlled pore size distribution that enables passive liquid feeding while maintaining control over hydraulic impedance. The porous structure allows liquid to pass through via capillary forces without requiring complex delivery systems, while the controlled pore sizes prevent clogging by filtering out particulates.
Solution Approach 2:
The emitter features different regions with distinct properties: a porous feeding region for liquid delivery and a nanotexturized emission region for ion production. This local differentiation allows the porous layer to control hydraulic impedance where needed while maintaining simple passive feeding elsewhere.
2Force
If the protrusion tip radius is reduced to concentrate electric field lines, then the electric field concentration is improved, but the mechanical strength of the emitter decreases
Solution Approach 1:
The emitter combines a sharp protrusion tip for electric field concentration with a robust base and nanotexturized surface for mechanical strength. The nanowire forest structure provides enhanced mechanical support while the sharp tip maintains high electric field concentration for efficient ion emission.
Solution Approach 2:
The emitter utilizes a composite structure combining the protrusion geometry for field concentration with a nanotexturized surface layer for mechanical reinforcement. This composite approach allows simultaneous optimization of both electric field properties and structural integrity.
3Reliability
If high voltage is applied to achieve pure ionic regime, then the ion emission quality is improved, but the onset voltage requirement increases power consumption
Solution Approach 1:
The emitter employs nanotexturization with controlled nanowire density and aspect ratio to modify the electric field distribution at the liquid interface. This parameter optimization enables pure ionic regime operation at reduced voltages by enhancing field concentration and improving liquid wetting characteristics.
Solution Approach 2:
The emitter utilizes capillary hydraulic forces in the porous structure to control liquid flow and meniscus formation. By optimizing the hydraulic properties of the porous layer, the system achieves stable ionic emission at lower voltages through improved liquid delivery control.
4Reliability
If nanotexturization is applied to control hydraulic resistance, then the hydraulic impedance control is improved, but the manufacturing complexity increases
Solution Approach 1:
The manufacturing process replaces complex mechanical nanotexturization methods with a chemical etching approach using colloidal particle masks. This substitution simplifies the manufacturing process while achieving the desired nanowire forest structure for hydraulic impedance control.
Solution Approach 2:
The nanotexturization parameters (nanowire density, height, diameter) are controlled by adjusting etching process variables such as particle concentration, etching time, and plasma power. This parameter-based control enables precise hydraulic impedance tuning through a relatively simple manufacturing 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 method enables precise control over hydraulic resistance and mechanical robustness, reducing clogging and degradation, allowing for high throughput and stable ionic emission with lower onset voltage.
Implementation Method 1
carrying out, in a direction perpendicular to the plate, a main etching process for removing a predetermined depth of the substrate not being protected by the particles, wherein the main etching process is configured for showing a low-relief etched surface with nanowires emerging from the low-relief surface in a direction perpendicular to the plate
Implementation Method 2
Electrospraying, also known as electrodynamic spraying, is an electrostatic acceleration of conducting liquids which has been used to provide and create molecular or ionic flows
Implementation Method 3
Electrospraying, also known as electrodynamic spraying, is an electrostatic acceleration of conducting liquids
Implementation Method 4
When an electric field is applied to the liquid/solid interface of a conductive liquid, charge migrates to the interface where the conductivity is discontinuous, causing the liquid to move
Implementation Method 5
Near the cone tip, the field can be strong enough to liberate ions directly from the surface, which is called field evaporation
Implementation Method 6
As the voltage is increased, the effect of the electric field becomes more prominent. As this effect of the electric field begins to exert a similar magnitude of force on the droplet as the surface tension does, a cone shape begins to form
Data Source
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AI summary
A first aspect of the present invention is related to a method for manufacturing an emitter for electrospray generators. The method comprising the steps of providing a substrate, presenting a plate and at least one protrusion, and then nanotexturizing the outer surface of the at least one protrusion. The present invention, according to a second aspect, also relates to the emitter resulting of the manufacturing method, the electrospray generator comprising the emitter according to the present invention and an electric space propulsion device comprising at least one electrospray generator thereof.