Dynamic Ion Gate Pulse Width for IMS Sensitivity and Resolution
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Solution Overview
Problem
Existing TOF-IMS systems face a trade-off between sensitivity and resolving power due to the need for a single ion gating time for multiple analytes, resulting in suboptimal detection of both high-mobility and low-mobility ions, where sensitivity for low-mobility ions is sacrificed for resolving power of high-mobility ions.
Innovation Solution
Implementing a method and apparatus that uses two different pulse widths for injecting ions from the ionization region into the drift region during ion gate de-energization, with a narrower pulse for high-mobility ions and a wider pulse for low-mobility ions, allowing for enhanced resolution and sensitivity of spectral traces for each type of ion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single ion gating time is used for multiple analytes, then the system can detect both high-mobility and low-mobility ions, but the resolving power for high-mobility ions deteriorates and sensitivity for low-mobility ions is sacrificed
Solution Approach 1:
The ion gate pulse width is made dynamic rather than fixed, allowing the system to adjust the gating time based on the mobility characteristics of the analytes being detected. High-mobility ions use shorter pulse widths (e.g., 50-200 microseconds) to maintain resolving power, while low-mobility ions use longer pulse widths (e.g., 200-1000 microseconds) to improve sensitivity, thereby resolving the contradiction between versatility and measurement precision
Solution Approach 2:
The system changes the temporal parameter (ion gate pulse width) according to the specific analyte mobility requirements. By varying this parameter dynamically, the system optimizes detection performance for different analyte types without requiring multiple fixed-configured systems, thus maintaining both adaptability and measurement precision
2Measurement precision
If a shorter ion gating time is used, then resolving power increases and peak width decreases, but sensitivity decreases rapidly below a certain threshold
Solution Approach 1:
Different ion gate pulse widths are applied locally to different mobility groups of ions. High-mobility ions receive shorter pulses optimized for their fast transit through the drift region, while low-mobility ions receive longer pulses to accumulate sufficient signal. This localized optimization resolves the contradiction between resolving power and sensitivity by tailoring the gating time to the specific requirements of each ion type
3Quantity of substance
If a longer ion gating time is used, then sensitivity for low-mobility ions improves, but resolving power for high-mobility ions deteriorates significantly
Solution Approach 1:
The system dynamically switches between different ion gate pulse width settings based on the analyte mobility being detected. Rather than using a static long pulse width that would broaden high-mobility ion peaks, the system employs short pulses for high-mobility ions to preserve peak sharpness and long pulses for low-mobility ions to enhance signal intensity, thus resolving the contradiction between sensitivity and resolving power
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 improved resolution of high-mobility analytes and increased sensitivity for low-mobility analytes by generating distinct spectral traces with optimized peak amplitudes and widths, effectively addressing the limitations of single-ion gating time systems.
Implementation Method 1
An ion gate (sometimes referred to as an ion shutter) that includes a conducting grid of interleaved wires, e.g., a Bradbury-Nielson gate, is maintained in a 'cut-off' condition that is configured to prevent an ion current to transmit from the ionization region. Energizing the ion gate deflects the ions in the ionization region to the gate wires, thereby collecting the ions and preventing them from flowing through the gate.
Implementation Method 2
Based on an ions' mass, charge, size, and shape (the ion mobility), the migration time through the drift region is characteristic of different ions, leading to the ability to distinguish different analyte species.
Implementation Method 3
ions are generated in an ionization region to increase the ion population therein
Implementation Method 4
Ions of lower mobility and longer drift times have wider spectrum peak widths as a function of diffusion in the axial direction along the drift region as compared to higher mobility ions with shorter drift times.
Data Source
AI summary
A method of detecting constituents in a sample includes generating a plurality of ions in an ionization region. The method also includes preventing the plurality of ions in the ionization region from flowing into a drift region through inducing a first voltage in a device positioned between the two regions. The method further includes injecting at least a portion of the ions from the ionization region into the drift region. The method also includes regulating the voltage in the device to a second voltage for a first predetermined temporal period, the second voltage less than the first voltage. The method further includes regulating the voltage in the device to the first voltage. The method also includes regulating the voltage in the device to the second voltage for a second predetermined temporal period, the second predetermined temporal period different from the first predetermined temporal period.