Variable-Volume Injection Valve for Nano-Scale HPLC
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Solution Overview
Problem
Current nano/capillary scale HPLC injection systems face challenges in achieving variable sample volumes, particularly for columns with IDs less than 300µm, as they often require precise positioning and are limited to full-loop injections, necessitating frequent replacement of injectors for different injection amounts.
Innovation Solution
A variable-volume injection valve comprising a stator and rotor with arcuate grooves, where the rotor is rotatable to vary the overlap between the grooves, allowing programmable adjustment of injection volume by changing the length of overlap, enabling both full and partial loop injections without physical changes to the injector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If external loops with tubing are used for nano/capillary scale chromatography, then injection volumes can be reduced, but tubing with small enough id is difficult to find and unswept volumes in loop ports add undesirable chromatographic variance
Solution Approach 1:
The sample loop is nested within the rotor groove, creating an integrated structure where the loop is formed by the groove geometry itself rather than being a separate external component. This eliminates the need for additional tubing and reduces unswept volume in loop ports, thereby reducing chromatographic variance while maintaining small injection volumes suitable for nano/capillary scale chromatography.
Solution Approach 2:
The invention transitions from external tubing-based loops to internal groove-based loops formed in the rotor and stator surfaces. This dimensional change from external to internal structure allows for precise control of the sample loop geometry and eliminates the chromaticographic variance issues associated with external tubing connections.
2Quantity of substance
If fixed loop rotary valves are used for nano/capillary scale, then injection volume can be controlled, but precise sample loading system is needed to precisely position sample in small volume
Solution Approach 1:
The invention introduces a variable overlap mechanism between the rotor and stator grooves that allows dynamic adjustment of the effective sample loop length. By rotating the rotor to different positions, the overlap between grooves changes, enabling programmable adjustment of injection volume without requiring a complex precise positioning system for sample loading. The system transforms a static fixed-loop design into a dynamic variable-volume design.
Solution Approach 2:
The invention changes the geometric parameter of the sample loop by varying the overlap length between rotor and stator grooves. This parameter change allows the same physical structure to deliver different injection volumes (10 to 250nL) by simply adjusting the rotational position, eliminating the need for complex precise positioning systems while maintaining control over injection volume.
3Measurement precision
If full-loop injections are used with internal loops, then injection accuracy is improved, but users must replace injector or rotor/stator when different injection amounts are needed
Solution Approach 1:
The invention makes the rotor-stator assembly multi-functional by enabling it to deliver a range of injection volumes (10 to 250nL) through variable overlap positioning. Instead of being limited to a single fixed volume, the same rotor-stator assembly can be configured for different injection amounts by adjusting the rotational position, eliminating the need for replacement and providing versatility while maintaining injection accuracy.
Solution Approach 2:
The invention transforms the static single-volume internal loop design into a dynamic variable-volume system. By allowing rotational adjustment of the rotor relative to the stator, the effective sample loop volume becomes dynamically changeable, enabling the same hardware to adapt to different injection requirements while preserving the accuracy benefits of internal loop design.
4Adaptability or versatility
If variable volume injection is achieved through pump and injection valve coordination, then injection volume flexibility is improved, but system complexity increases
Solution Approach 1:
The invention merges the volume control function directly into the injection valve structure through the variable overlap mechanism between rotor and stator grooves. Instead of requiring separate pump coordination and valve control systems, the volume control is integrated into the valve's mechanical structure, simplifying the overall system while maintaining injection volume flexibility.
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 2C~3
AI summary
Variable- volume injection valves include a stator and a rotor. The stator has a first port, a second port, and a contact surface with a groove therein. The first port opens into the stator groove. The rotor has a contact surface with a groove therein. The contact surface of the rotor is urged against the contact surface of the stator such that the rotor groove opposes the stator groove with one end of the rotor groove overlapping the stator groove and the opposite end of the rotor groove overlapping the second port of the stator. The overlapping grooves of the rotor and stator provide a fluidic channel between the first and second ports of the stator. The rotor is movable with respect to the stator in order to vary a length of overlap between their overlapping grooves.