Passive Vapor Pre-Concentrator With Progressive Heating Injection
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Solution Overview
Problem
Conventional microscale gas chromatographic systems face challenges in achieving sharp injection bands and efficient power consumption due to the use of pumps for air sample circulation, leading to tradeoffs between injection band width, pre-concentration factors, and power dissipation.
Innovation Solution
A microscale collector-injector device comprising a passive pre-concentrator and a progressively-heated injector, which uses passive diffusion for sample collection and radial flow to minimize back-diffusion, coupled with sequentially actuated heating units to produce ultra-sharp injection bands, reducing power consumption and extending operational life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pumps are used for air sample circulation, then sampling efficiency is improved, but power consumption increases
Solution Approach 1:
The patent replaces the mechanical pump system with a passive diffusion-based sampling system. The microscale diffusion channels enable vapor transport through concentration gradients without mechanical circulation, eliminating pump power requirements while maintaining sampling efficiency through optimized diffusion pathways and collection material geometry.
Solution Approach 2:
The sampling system utilizes self-driven passive diffusion where the concentration gradient between the external environment and the collection material automatically drives vapor transport. This self-service mechanism eliminates the need for external power sources during the sampling phase, significantly reducing overall power consumption.
2Measurement precision
If conventional injection methods are used, then injection band width is acceptable, but desorption efficiency decreases
Solution Approach 1:
The heating process is segmented into multiple sequential zones along the extraction channel. Different segments of the collection material are heated at different times and temperatures, enabling precise control over desorption timing and location. This segmentation produces ultra-sharp injection bands while maximizing desorption efficiency by targeting specific compound regions.
Solution Approach 2:
The system employs dynamic, time-varying temperature profiles rather than static heating. The heating units are activated sequentially and for varying durations to create moving temperature fronts that drive compounds through the extraction channel in sharp, focused bands, simultaneously achieving narrow injection widths and high desorption efficiency.
3Productivity
If heating is applied to the compartment, then desorption efficiency is improved, but back-diffusion losses increase
Solution Approach 1:
The system performs preliminary concentration of vapors in the collection material before heating-induced desorption occurs. The passive diffusion collection phase accumulates compounds in the extraction channel, creating a concentrated reservoir that can then be efficiently desorbed with minimal back-diffusion losses when heated.
Solution Approach 2:
Heating is applied locally to specific zones of the collection material rather than uniformly throughout the entire compartment. This localized heating targets the regions containing concentrated compounds, achieving high desorption efficiency while minimizing thermal effects in other regions that could cause back-diffusion losses.
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 device achieves sharp injection bands with reduced power consumption, allowing for up to 50 times daily operation for 2 years on battery power, while maintaining high desorption efficiency and minimizing back-diffusion losses.
Implementation Method 1
The μPP device is configured to collect a sample at a known rate by using passive diffusion, without use of artificial circulation
Implementation Method 2
The heating unit is disposed in thermal communication with the second substrate. The heating unit is configured to heat the compartment
Implementation Method 3
The first collection material is disposed within the compartment and configured to capture compounds within a first range of vapor pressures
Data Source
AI summary
A microscale collector and injector device comprises a microscale passive pre-concentrator (μPP) and a microscale progressively-heated injector (μPHI). The μPP devices comprises first and second substrate portions, a first collection material, a μPP heater, and an outlet. The first substrate portion defines an array of microscale diffusion channels. The first and second substrate portions cooperate to define a first compartment in fluid communication with the diffusion channels. The first collection material is disposed within the first compartment, at least partially surrounding the outlet. The μPP heater is disposed in thermal communication with the second substrate portion. The μPHI device comprises third and fourth substrate portions, a second collection material, and a plurality of μPHI heaters. The third and fourth substrate portions cooperate to define a second compartment. The second collection material is disposed within the second compartment. The μPHI heaters are disposed in thermal communication with the second compartment.