Quadrupole Mass Filter Electrode EDM Fabrication

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Solution Overview

Problem

Conventional methods for miniaturizing quadrupole mass spectrometers struggle to achieve precise hyperbolic electric field profiles due to limitations in machining complex geometries at the micro-scale, leading to suboptimal performance in miniature devices.

Innovation Solution

The method involves back-cutting erodible metal workpieces, mounting them in an insulating housing, and using electrode-discharge machining to create a hyperbolic profile, allowing for the generation of a substantially ideal hyperbolic electric field with a small inscribed radius, independent of pre-machining accuracy and reassembly errors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If conventional MEMS-based microengineering methods are used to miniaturize quadrupole mass spectrometers, then device size is reduced, but manufacturing precision of hyperbolic electrode profiles deteriorates

Engineering Contradiction:

Improvedevice sizeVSAvoidhyperbolic electrode profile precision

Core Design Contradiction:

Volume of moving objectVSManufacturing precision

Solution Approach 1:

The patent replaces conventional mechanical microengineering methods (MEMS) with electrical discharge machining (EDM). This substitution allows for precise hyperbolic profile fabrication at micro-scale by using controlled electrical discharges to erode metal workpieces, achieving manufacturing precision that mechanical methods cannot attain while maintaining miniaturization benefits

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the machining parameter regime from mechanical cutting to electrical discharge erosion. By controlling discharge current, pulse duration, and electrode geometry, the method achieves precise hyperbolic profiles in miniaturized devices that would be impossible with conventional mechanical microengineering

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If simpler cylindrical or planar electrode geometries are used in miniaturized devices, then ease of manufacture is improved, but electric field profile quality deteriorates

Engineering Contradiction:

Improveelectrode fabrication simplicityVSAvoidelectric field profile accuracy

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent replaces simple cylindrical or planar electrode geometries with precisely machined hyperbolic profiles using electrical discharge machining. The EDM process makes complex hyperbolic geometries as easy to manufacture as simple shapes, while achieving the ideal hyperbolic electric field profile required for optimal quadrupole mass spectrometer performance

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of manufacture

If pre-machining and reassembly methods are used to fabricate miniature quadrupoles, then ease of manufacture is improved, but manufacturing precision deteriorates due to reassembly errors

Engineering Contradiction:

Improvefabrication process simplicityVSAvoidelectrode alignment accuracy

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent merges the electrode fabrication and assembly processes into a single integrated electrical discharge machining operation. The four hyperbolic electrodes are machined in situ within the insulating housing, eliminating separate pre-machining and reassembly steps that would introduce alignment errors and reduce manufacturing precision

Inventive Principle:

Principle #5Merging (Combining)

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 approach enables the fabrication of quadrupole mass filters or ion traps with high accuracy and small geometries, achieving an average resolution of 50 or more (m/Δm) at 50% peak height, and generating a substantially ideal hyperbolic electric field with an inscribed radius of 0.9 mm or less, enhancing the performance of miniaturized mass spectrometers.

Implementation Method 1

generating a plurality of electrical discharges between the erodible metal workpiece and a wire electrode as the wire electrode passes through the axial bore to erode the erodible metal of the first part of the erodible metal workpiece to a hyperbolic profile

Methodology Applied

Scientific EffectElectrical discharge machining: Electrical Discharge Machining

Data Source

PatentUS8648276B2Method for fabrication of a quadrupole mass filter or quadrupole ion trap using electrode discharge machining

Publication Date: 2014.02.11 ADVANCED SENSORS

AI summary

A method for fabricating a quadrupole mass filter (QMF) or quadrupole ion trap (QIT) capable of generating a hyperbolic electric field. The method comprises: (a) cutting four elongate erodible metal workpieces axially at opposing extremities; (b) parallel mounting the four elongate erodible metal workpieces axially in an elongate slot in an insulating housing in a mutually spaced apart disposition such that an axial bore is formed therebetween whereby a first part of each elongate erodible metal workpiece is freely inward facing and the cutting forms a recess remote from the axis of the insulating housing; (c) electrically connecting the erodible metal workpieces; and (d) generating electrical discharges between the erodible metal workpiece and a wire electrode as the wire electrode passes through the axial bore to erode the erodible metal of the first part of the erodible metal workpiece to a hyperbolic profile.