Electrospray Emitter Shielding for Mass Spectrometry
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Solution Overview
Problem
Conventional electrospray ionization sources face interference issues due to electric field interactions between closely spaced emitters, leading to non-uniform ion emission and reduced transmission efficiency into mass spectrometers, especially when multiple emitters are packed closely together.
Innovation Solution
The use of supplementary shield electrodes, configured to conform to the electric field of individual emitters, decouples the electric fields between emitters, allowing for closer spacing without increased voltage requirements, and optimizing the electrode shape and position to emulate the conditions of a single emitter operating in isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple emitters are packed closely together to increase overall flow rate, then productivity is improved, but electric field interference between emitters causes non-uniform ion emission and reduced transmission efficiency
Solution Approach 1:
A shield electrode is introduced as an intermediary component between adjacent emitters. This shield electrode, configured to conform to the electric field distribution of individual emitters, acts as a mediator that decouples the electric fields between closely spaced emitters, preventing field interference while allowing the emitters to be packed closely together for increased productivity
2Device complexity
If multiple emitters are packed closely together, then device complexity is reduced, but higher voltages are required to overcome electric field interference
Solution Approach 1:
The shield electrode serves as a mediator that blocks electric field interference between adjacent emitters, allowing them to operate at standard voltage levels without the need for increased voltage to overcome field cancellation effects that would otherwise occur in closely packed emitter arrays
3Reliability
If emitter spacing is increased to reduce electric field interference, then ion emission uniformity is improved, but the overall flow rate decreases
Solution Approach 1:
The shield electrode enables closely spaced emitter configuration by mediating the electric field interactions, allowing emitters to be positioned closer together (increasing productivity) while maintaining uniform ion emission (preserving reliability) that would otherwise require larger spacing
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 configuration reduces cross-talk between emitters, achieving uniform ion emission and efficient ion transfer into mass spectrometers, similar to a single emitter setup, without the need for higher voltages or additional power supplies, enabling denser emitter packaging and improved analytical results.
Implementation Method 1
supplementary shield electrodes, configured to conform to the electric field of individual emitters, decouples the electric fields between emitters
Implementation Method 2
an electric field induced between the capillary electrode and the conducting liquid initially causes a Taylor cone to form at the tip of the tube where the field becomes concentrated. Fluctuations cause the cone tip to break up into fine droplets which are sprayed, under the influence of the electric field
Implementation Method 3
An electric field induced between the capillary electrode and the conducting liquid initially causes a Taylor cone to form at the tip of the tube where the field becomes concentrated
Implementation Method 4
An optional drying gas, which may be heated, may be applied so as to cause the solvent in the droplets to evaporate
Implementation Method 5
The ions are attracted to and pass through a capillary or sampling orifice into the mass analyzer
Data Source
Figure 1A
Figure 1B
Figure 2A~2C
AI summary
An electrospray ion source that comprises (a) an emitter capillary having (i) an internal bore for transporting a liquid sample, (ii) an electrode portion for providing a first applied electrical potential and (iii) an emitter tip for emitting charged particles generated from the liquid sample and (b) a counter electrode for providing a second applied electrical potential different from the first applied electrical potential is characterized by (c) a shield electrode disposed at least partially between the counter electrode and the emitter tip of the emitter capillary for providing a third applied electrical potential intermediate to the first and second applied electrical potentials, the shield electrode contoured in the form of a portion of an electrical equipotential surface formed, in the absence of the shield electrode, under application of the first and second applied electrical potentials to the electrode portion of the emitter capillary and to the counter electrode, respectively.