Planar DMS Pre-Filter Assembly for Mass Spectrometry
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Solution Overview
Problem
Cylindrical differential mobility spectrometers (DMS) used as pre-filters for mass spectrometers require frequent attachment and detachment, leading to issues like sample contamination, time-consuming processes, wear, reduced reliability, and increased size and power requirements due to high transport gas flow rates, which are undesirable for portable and field-deployable applications.
Innovation Solution
A planar DMS system with a micromachined electrospray head and guiding electrodes, allowing for independent control of ion introduction and desolvation, and a DMS filter that can be deactivated instead of disconnected, reducing ion diffusion and gas flow rates, thereby enhancing sensitivity and compactness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cylindrical DMS is used as a pre-filter for mass spectrometry, then ion filtering capability is achieved, but frequent attachment and detachment is required leading to sample contamination, wear, and reduced reliability
Solution Approach 1:
The DMS filter electrodes are designed to be dynamically controllable through voltage application. By applying asymmetric voltage waveforms, the filter can be activated or deactivated without physical disconnection, allowing ions to pass freely when deactivated and selectively filtered when activated. This dynamic control eliminates the need for frequent attachment and detachment operations.
2Reliability
If a cylindrical DMS is used as a pre-filter, then ion filtering is achieved, but the system size and power requirements increase
Solution Approach 1:
The patent replaces the mechanical cylindrical DMS structure with an integrated planar DMS design where the filter electrodes are formed directly on a substrate. This substitution of mechanical assembly with an integrated planar structure reduces system size, weight, and power requirements while maintaining ion filtering performance.
3Quantity of substance
If a cylindrical DMS is used as a pre-filter, then ion concentration is achieved, but ion diffusion occurs requiring terminus and trap regions
Solution Approach 1:
The patent combines the ion concentration function with the ion filtering function in a single integrated planar DMS structure. The filter electrodes serve dual purposes: selectively filtering ions based on their mobility characteristics and simultaneously concentrating ions through the applied electric fields. This merging eliminates the need for separate terminus and trap regions required by cylindrical designs.
4Measurement precision
If a cylindrical DMS is used as a pre-filter, then ion analysis is achieved, but the process is time-consuming due to frequent attachment and detachment
Solution Approach 1:
The integrated planar DMS design enables continuous ion analysis without interruption for attachment or detachment operations. The filter remains permanently mounted and can be dynamically activated or deactivated through voltage control, ensuring continuous useful action and eliminating time losses associated with mechanical assembly changes.
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 planar DMS system improves ion focusing and detection efficiency, reduces system size and power consumption, and allows for continuous ion flow without the need for frequent disconnection, enhancing the reliability and portability of DMS-MS systems.
Implementation Method 1
A differential mobility spectrometer (DMS), also referred to as a Field Asymmetric Ion Mobility Spectrometer (FAIMS), also analyzes ions that are flowing through a gas or mixture of gases. However, unlike an IMS, a DMS subjects the ions to a time-varying (e.g., asymmetric) field as the ions flow through an analytical gap between filter electrodes that apply the asymmetric field.
Implementation Method 2
A compensation field is also typically generated one of the filter electrodes (by applying a DC compensation voltage to the electrode) that enables the DMS to pass through a selected ion species.
Implementation Method 3
A planar DMS system with a micromachined electrospray head and guiding electrodes, allowing for independent control of ion introduction and desolvation
Implementation Method 4
A planar DMS system with a micromachined electrospray head and guiding electrodes, allowing for independent control of ion introduction and desolvation
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A pre-filter assembly including a differential mobility spectrometer (DMS) that is configured to be in-line with a mass spectrometer (MS) such that the MS continuously receives carrier flow from the DMS when the DMS filtering fields are removed.