Ion Extraction Electrode Layout for Low-Loss IMS Focusing
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Solution Overview
Problem
Ion loss and related degradation of the ion detection signal is a significant problem in ion mobility spectrometry and mass spectrometry, limiting the performance and preventing the extension of ion analysis techniques to a broader range of applications.
Innovation Solution
The use of a sequence of electrodes configured to receive specific voltages to create an electric field gradient, including voltage dips and time varying voltages, to manipulate ions at atmospheric pressure, enhancing ion signal and reducing loss in atmospheric flow tubes and ion mobility spectrometers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ion residence time in the flow tube is increased to improve ion-molecule reaction time and detection sensitivity, then the number of ion-molecule collisions increases, but ion loss increases causing degradation of the ion detection signal
Solution Approach 1:
The patent applies dynamic voltage control to electrodes, switching between different voltage configurations (ion trapping mode vs. ion extraction mode) to optimize performance. The system dynamically adjusts electric field strength and distribution along the flow tube to maintain ions in the reaction region while preventing excessive loss, resolving the contradiction between extended residence time and ion signal preservation
Solution Approach 2:
The patent changes electrical parameters (voltage magnitude, polarity, and temporal profiles) applied to the electrode system to control ion behavior. By adjusting voltage parameters, the system can enhance ion-molecule reaction efficiency while compensating for ion losses, thereby improving detection sensitivity without excessive ion depletion
2Device complexity
If common voltages are applied to the flow tube and drift tube to simplify the system, then device complexity is reduced, but ion signal strength and detection sensitivity deteriorate
Solution Approach 1:
The patent segments the voltage control system into independent controllable sections (flow tube electrodes and drift tube electrodes), allowing separate optimization of voltage parameters for each region. This segmentation enables enhanced ion signal strength through region-specific electric field control while maintaining manageable system complexity through modular voltage configuration
Solution Approach 2:
The electrode system is designed with multi-functionality, where the same physical electrodes can operate in different modes (ion trapping, ion extraction, ion guidance) by changing voltage configurations. This universal design allows the system to achieve high ion signal strength without proportionally increasing device complexity, as the hardware serves multiple analytical functions
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 increases ion signal strength and reduces ion loss, enabling improved detection sensitivity and broader application of ion analysis techniques, particularly in smaller, portable devices for real-time chemical threat detection.
Implementation Method 1
the electrodes are configured to receive respective voltages to produce an electric field in the volume that urges ions to propagate along the ion path downstream towards the ion outlet
Implementation Method 2
the voltage dip is configured to extract ions from a position upstream from the at least one intermediate electrode of the first sequence portion by projecting electrical field lines upstream to a field free region
Implementation Method 3
a central electrode arranged longitudinally along the flow tube axis and configured to receive a time varying voltage configured to reduce a loss of ions as the gas and ions flow along the flow tube volume to the flow tube outlet
Data Source
AI summary
Apparatus include a plurality of electrodes arranged in a sequence along a propagation axis between an ion inlet and an ion outlet to define an ion path and volume, wherein the electrodes are configured to receive respective voltages to produce an electric field in the volume that urges ions to propagate along the ion path downstream towards the ion outlet, wherein the sequence includes at least a first sequence portion including first and last electrodes configured to receive voltages according to a first function, and including at least one intermediate electrode situated between the first and last electrodes wherein the at least one intermediate electrode is configured to receive a voltage defining a voltage dip relative to the first function. Atmospheric flow tubes include a tube body and a central electrode.