Conductive-Coated Electrospray Emitter for Corona Discharge Suppression
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Solution Overview
Problem
Conventional electrospray emitters face limitations in negative ion mode due to the onset of corona discharge at lower potentials than optimal, leading to degraded analytical performance in mass spectrometry.
Innovation Solution
An electrospray emitter with a cannula coated with an electrically conductive material, featuring a rounded tip and an internal conductive coating extending beyond the outlet aperture, which inhibits the formation of corona discharge and allows for higher ESI potentials without degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrospray emitter is used in negative ion mode, then ionization can occur, but corona discharge occurs at lower potentials than optimal, degrading analytical performance
Solution Approach 1:
The patent applies a conductive coating specifically to the emitter tip region where the electric field is most intense and corona discharge originates. This localized modification changes the electrical properties at the critical location without altering the entire emitter structure, thereby suppressing corona discharge at the tip while maintaining overall system functionality.
Solution Approach 2:
The conductive coating changes the electrical conductivity parameter of the emitter tip surface. This parameter change allows the emitter to withstand higher potentials in negative ion mode by distributing the electric field more evenly, preventing the field concentration that leads to corona discharge onset.
2Power
If higher ESI potentials are applied to improve ionization, then signal intensity increases, but corona discharge occurs earlier, limiting the maximum usable potential
Solution Approach 1:
The conductive coating is applied locally to the emitter tip where the electric field concentration causes corona discharge. This localized treatment allows higher potentials to be applied globally while the coated region specifically manages the field distribution to prevent discharge, enabling higher signal intensity without stability loss.
Solution Approach 2:
The conductive coating transforms the harmful effect of field concentration (which causes corona discharge) into a beneficial uniform field distribution. By making the tip surface conductive, the field lines redistribute evenly across the coated surface, converting what would be a discharge initiation point into a stable ionization region that supports higher potentials.
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 solution enhances ionization performance by preventing corona discharge, enabling higher ESI potentials and improving signal intensity and stability, thus overcoming the limitations of conventional electrospray emitters.
Implementation Method 1
an electrically conductive coating covering at least a portion of an external surface and at least a portion of an internal surface of the emitter end
Implementation Method 2
an electric potential difference between the electrospray electrode and a counter electrode generates a strong electric field within the ionization chamber that electrically charges the liquid sample
Implementation Method 3
the electric field generated within the ionization chamber causes the liquid discharged from the electrospray electrode, needle or nozzle to disperse into a plurality of charged micro-droplets drawn toward the counter electrode if the charge imposed on the liquid's surface is strong enough to overcome the surface tension of the liquid
Implementation Method 4
an electrically conductive coating covering at least a portion of an external surface and at least a portion of an internal surface of the emitter end
Data Source
AI summary
An electrospray probe for use in an electrospray ion source is disclosed, which comprises a cannula extending from a proximal end having an inlet aperture for receiving a liquid sample containing at least one analyte to a discharge emitter end having an outlet aperture through which charged liquid droplets containing ions of said analyte are discharged, and an electrically conductive coating covering at least a portion of an external surface and at least a portion of an internal surface of said emitter end.