Tapered Ion Mobility Channel for Precise Ion Separation
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Solution Overview
Problem
Trapped ion mobility spectrometry is limited in controlling the linear velocity of the carrier gas, the effectiveness of the RF field in confining ions, and the control of the electric field along the ion channel, which hampers the separation and identification of ions based on their mass-to-charge ratio and collisional cross-section.
Innovation Solution
An ion mobility spectrometer with a continuous ion channel having a varying diameter, equipped with a resistive conductor generating an electric field and electrodes producing a confining field, allows for adjustable DC and time-varying electrical signals to control ion movement and separation, enhancing the separation of ions by varying the speed of the carrier gas and electric field along the ion channel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional ion channel design is used, then the structure is simple, but the control over linear velocity of carrier gas and electric field distribution is insufficient
Solution Approach 1:
The ion channel is divided into multiple segments with different diameters along its length. Each segment can be independently controlled to provide different linear velocities to the carrier gas, enabling precise control over ion transport while maintaining a manageable structural complexity through modular design.
Solution Approach 2:
Different portions of the ion channel are given different local properties through varying diameter specifications. The channel has a first section with a first diameter and a second section with a second diameter, creating localized regions that optimize specific functions such as ion confinement, velocity control, and electric field distribution.
2Reliability
If RF field strength is increased to improve ion confinement, then ion separation effectiveness improves, but energy consumption increases
Solution Approach 1:
The system optimizes ion confinement by changing multiple parameters simultaneously rather than simply increasing RF field strength. The varying ion channel diameter, carrier gas flow rate, and electric field strength are coordinated to achieve effective ion confinement with reduced energy consumption, as the geometric constraints of the segmented channel provide additional confinement mechanisms.
3Measurement precision
If the ion channel diameter is reduced to improve resolution, then ion separation precision improves, but carrier gas flow control becomes more difficult
Solution Approach 1:
The ion channel is segmented into sections with different diameters, allowing the system to achieve high resolution in specific regions while maintaining easier-to-control flow characteristics in other regions. The segmented design provides flow expansion sections that facilitate carrier gas flow control while maintaining narrow sections for high-resolution ion separation.
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 configuration provides improved control over ion separation, allowing for more precise identification and separation of ions based on their mass-to-charge ratio and collisional cross-section, increasing the resolution and efficiency of the ion mobility spectrometry process.
Implementation Method 1
a resistive conductor extending along the ion channel and configured to generate an electric field along the ion channel when a DC signal is applied across the resistive conductor
Implementation Method 2
a radio frequency (RF) electric field radially confines (traps) ions in an ion channel while a flowing carrier gas forces (drags) ions along the ion channel
Implementation Method 3
a flowing carrier gas forces (drags) ions along the ion channel
Implementation Method 4
an electric field exerts an electric force on the ions, in a direction opposite the direction followed by the flowing carrier gas
Data Source
AI summary
An ion mass spectrometer that has an ion channel shaped to modify the speed of a carrier gas as the carrier gas traverses the ion channel. In one case, the ion channel has a tapered shape, which continuously varies the gas flow rate. This arrangement is made using conductors located in the drift tube. This controlled variation in speed together with the control of the axial electric field in the ion channel, provide greater control on the separation of ions in the ion channel. A method of analyzing ions based on a variation of at least one of axial electric field and of the speed of the flowing gas in the ion channel is also disclosed.