Pulsed Flow Ion Mobility Spectrometer Miniaturization
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Solution Overview
Problem
Conventional ion mobility spectrometers face limitations in miniaturization due to the need for large drift tubes and high voltages, as well as the requirement for continuous gas flow, which restricts their size and safety, especially in portable devices used for detecting explosives and chemical agents.
Innovation Solution
The use of a pulsed gas flow operation in an ion mobility spectrometer, which allows for a solid-state construction without a gas pump, utilizing an ion filter with interdigitated electrodes to drive ions through a filter using electric fields, and employing a pulsed pump to pre-concentrate ions and improve sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a long drift tube is used to improve resolution in TOF ion mobility spectrometry, then measurement precision is improved, but device complexity and size increase, restricting miniaturization
Solution Approach 1:
The patent replaces the mechanical drift tube system with an electric field-based ion mobility filter. Instead of relying on physical drift tube length for resolution, the invention uses controlled electric fields to separate ions based on their mobility characteristics, enabling high-resolution analysis in a compact solid-state device without requiring long drift paths
Solution Approach 2:
The invention changes the operating parameters from continuous high voltage to pulsed asymmetric electric fields. By applying alternating high and low voltage pulses to the filter electrodes, ions are selectively transmitted based on their mobility, achieving high resolution with much shorter physical dimensions than conventional drift tubes
2Measurement precision
If high electric field strengths are used to improve ion mobility separation, then measurement precision is improved, but safety hazards increase and device miniaturization is restricted
Solution Approach 1:
The patent employs periodic pulsed electric fields instead of continuous high voltage. The asymmetric pulse waveform (with distinct high-voltage and low-voltage phases) creates temporary high field strengths for ion separation while allowing the field to reset between pulses, reducing overall power requirements and safety hazards compared to continuous operation
Solution Approach 2:
The invention uses dynamically switching electric fields that adapt their strength and direction based on the ion separation requirements. The electric field parameters (amplitude, duration, waveform) are optimized to provide sufficient separation power only when needed, rather than maintaining constant high voltage, thereby reducing safety risks and power consumption
3Ease of operation
If a pump is used to generate constant gas flow in FAIMS, then ion transport is improved, but device complexity increases and miniaturization is limited
Solution Approach 1:
The patent replaces the mechanical gas pump system with an electric field-driven ion transport mechanism. Ions are propelled through the device by asymmetric electric field pulses rather than by continuous gas flow, eliminating the need for bulky pump components and enabling solid-state miniaturization while maintaining effective ion transport
Solution Approach 2:
The invention extracts and eliminates the gas pump component from the FAIMS system. By using electric fields to drive ion mobility separation and transport, the design removes the mechanical pumping system entirely, simplifying the device architecture and enabling portable implementations
4Productivity
If continuous gas flow is used to transport ions, then ion transport efficiency is improved, but sensitivity decreases due to analyte dilution
Solution Approach 1:
The patent uses periodic pulsed gas flow synchronized with the electric field cycles. Gas flow is activated only during specific phases of the asymmetric pulse waveform to transport ions, while remaining stopped during other phases to allow analyte accumulation. This intermittent flow maintains ion transport efficiency while minimizing dilution of the analyte signal
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 miniaturization and increased sensitivity by pre-concentrating ions, reducing the size and power requirements of the spectrometer, while maintaining robustness and reducing the dilution of analytes, allowing for more efficient detection of chemical agents.
Implementation Method 1
a pump operable to draw gas through the ion filter in pulsed operation
Implementation Method 2
utilizing an ion filter with interdigitated electrodes to drive ions through a filter using electric fields
Implementation Method 3
employing a pulsed pump to pre-concentrate ions and improve sensitivity
Implementation Method 4
Ion mobility spectrometry relies on the movement of different ion species through an electric field to a detector
Data Source
AI summary
An ion mobility spectrometer is described which makes use of a pulsed flow pump to draw gas through an ion filter in pulsed operation. A gas counterflow may also be provided, in some embodiments this may also be a pulsed counterflow.