Liquid Junction Assembly With Holed Plate for Dead Volume Reduction
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Solution Overview
Problem
Current methods for joining capillaries in liquid chromatography and mass spectrometry systems are prone to dead volumes due to inaccuracies in drilling small holes for connecting capillaries, especially at the micro and nanoscale, leading to experimental failures.
Innovation Solution
A liquid junction assembly using a discrete holed plate or shim element instead of a conventional integral web, allowing for precise alignment and minimization of dead volumes by using a plate with a hole smaller than the conduit cross sections, assembled with the bodies to ensure accurate alignment and secure connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a discrete holed plate is used instead of an integral web, then manufacturing precision of the hole is improved, but device complexity increases
Solution Approach 1:
The liquid junction assembly is divided into separate components: a body, a discrete plate with the through-hole, and capillary conduits. The plate is positioned between the bodies and secured independently, allowing the hole to be manufactured with high precision using specialized techniques while keeping the overall assembly modular and manageable.
Solution Approach 2:
The discrete plate acts as an intermediary element between the two bodies, providing a precisely positioned through-hole that connects the capillary conduits. This intermediate component isolates the complexity of hole positioning from the main body structures, allowing each part to be optimized independently.
2Ease of manufacture
If mechanical drilling is used to create the through hole, then ease of manufacture is improved, but manufacturing precision deteriorates
Solution Approach 1:
The patent replaces traditional mechanical drilling with laser drilling technology. The laser beam can be precisely positioned and focused to create accurately located holes without the limitations of mechanical drill bit reach and alignment. This substitution maintains ease of manufacture through automated laser processes while dramatically improving hole positioning accuracy to within 50 μm of the center line.
3Manufacturing precision
If laser drilling is used to create the through hole, then manufacturing precision is improved, but ease of manufacture deteriorates
Solution Approach 1:
The plate with the laser-drilled hole is manufactured as a separate preliminary component before final assembly. This allows the complex laser drilling operation to be performed on a small, accessible workpiece with precise positioning fixtures, rather than attempting to drill through the entire assembled liquid junction. The pre-manufactured plate is then easily integrated into the final assembly.
4Ease of manufacture
If the hole is positioned far from the passage end, then ease of manufacture is improved, but manufacturing precision deteriorates
Solution Approach 1:
Instead of positioning the hole far from the passage end along the axial dimension, the discrete plate provides a new dimensional plane for hole creation. The plate's thickness creates a accessible working surface where the hole can be precisely positioned and drilled perpendicular to the passage axis, eliminating the reach limitations of mechanical drilling while maintaining excellent alignment accuracy.
Data Source
AI summary
A liquid junction assembly for providing a flow connection between two tubular conduits. The assembly includes respective bodies configured to define elongated passages of respective first and second cross sections to receive and locate the respective tubular conduits, a plate with at least one hole therethrough of a third cross section smaller than the first and second cross sections, and a seat for the plate, defined in a face of one or both of the bodies. The bodies and the plate are assembled with the plate in the seat and the elongated passages and the hole aligned along a common axis.