Segmented Ion Gate for FAIMS Carrier Gas Exchange
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Solution Overview
Problem
Field Asymmetric Ion Mobility Spectroscopy (FAIMS) is hindered by neutral molecules or atoms in the carrier gas, which reduce ion separation efficiency and introduce noise in the detector electrode, necessitating a method to transfer ions from a first carrier gas to a second carrier gas.
Innovation Solution
An ion gate with a channel connecting two volumes, featuring electrodes that apply an electric field to transport ions from the first carrier gas to the second, with channel dimensions optimized for efficient ion transfer, such as lengths less than 1 mm and cross-sectional areas between 1 μm² and 10,000 μm², fabricated using high resistivity materials like silicon or quartz.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ions are transferred from a first carrier gas to a second carrier gas using a conventional ion gate, then ion separation efficiency is improved, but neutral molecules or atoms in the carrier gas reduce the ability to fractionate ions and contribute to noise in the detector electrode
Solution Approach 1:
The ion gate is divided into multiple discrete channels (e.g., 10-1000 channels) instead of a single open aperture. Each channel acts as an independent pathway for ion transport, allowing precise control over which ions pass through while blocking neutral molecules. This segmentation enables the system to maintain high ion transmission efficiency while effectively filtering out noise-causing neutral species.
Solution Approach 2:
The patent introduces a carrier gas exchange mechanism as an intermediary step between ion generation and detection. Ions are first generated in a first carrier gas, then transferred through the segmented ion gate to a second carrier gas with different properties. This intermediary transfer allows the system to optimize ion separation in the first gas while using the second gas to minimize noise and enhance detection, effectively mediating between conflicting requirements.
2Productivity
If the channel length is reduced to enhance ion transfer efficiency, then ion mobility separation is improved, but manufacturing precision becomes more challenging
Solution Approach 1:
The ion gate channels are implemented using thin film structures (e.g., silicon nitride, silicon oxide) deposited on a substrate. These thin films can be fabricated with precise thickness control using standard semiconductor manufacturing techniques like chemical vapor deposition (CVD) or atomic layer deposition (ALD). The thin film approach allows creation of channels with lengths in the micrometer range while maintaining manufacturing feasibility and dimensional accuracy.
Solution Approach 2:
The patent systematically varies channel parameters (length, width, depth, aspect ratio) to optimize performance. By changing these geometric parameters within specific ranges (e.g., channel length 10-500 micrometers, width 1-100 micrometers), the invention achieves high ion transfer efficiency while staying within manufacturing capabilities. The optimized parameter ranges balance the competing demands of short channel length for efficiency and manufacturability for precision.
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
Effectively separates ions by transferring them from a first carrier gas with unknown neutral species to a second with known composition, minimizing interference and enhancing downstream analysis by reducing noise and improving ion mobility separation.
Implementation Method 1
Ions are transported from the first volume to the second volume through the channel under an electric field produced by the first and second electrodes
Implementation Method 2
the first and second electric potential providing an electric driving force to transport ions in the first volume to the second volume through the at least one channel
Data Source
AI summary
An ion gate is disposed between a first volume occupied by a first carrier gas and ions of the first carrier gas and a second volume occupied by a second carrier gas. The ion gate includes at least one channel connecting the first volume to the second volume, a first electrode disposed on an inlet surface of the ion gate facing the first volume, and a second electrode disposed on an outlet surface of the ion gate facing the second volume. Ions are transported from the first volume to the second volume through the channel under an electric field produced by the first and second electrode.