Magnetic Pole Piece Assembly for Homogeneous Assay Fields
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Solution Overview
Problem
Existing magnetic assemblies for assays face issues with non-homogeneous magnetic field strength, interference with reaction kinetics, and impractical size for point-of-care testing due to high power consumption and localized magnetic fields.
Innovation Solution
A magnetic assembly with a pole piece and aligned magnetic elements, configured to spread magnetic field strength evenly over an extended area, using a rotatable arm to adjust magnetic field orientation for precise sample handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If high-power permanent magnets or large coil electromagnets are used to generate strong magnetic fields, then magnetic field strength is improved, but device size and power consumption increase making them impractical for point-of-care testing
Solution Approach 1:
The magnetic field generation system is segmented into multiple permanent magnet assemblies, each contributing to the overall magnetic field. This allows distribution of the magnetic field generation task across multiple smaller components rather than relying on a single large high-power magnet, reducing overall power consumption while maintaining field strength
Solution Approach 2:
The invention changes the operational parameters by using permanent magnets with specific remanence values (Br ≥ 1.05 T) and configuring them in assemblies with precise geometric relationships. This allows generation of clinically useful magnetic fields (≥0.2 T at the isocenter) without requiring continuous high power input, as the permanent magnets provide sustained field generation
2Measurement precision
If magnetic field strength is increased to improve assay sensitivity, then measurement precision is improved, but magnetic field homogeneity deteriorates causing localized field concentration
Solution Approach 1:
The magnetic assembly is designed with non-uniform magnetization distribution across different regions. Specific zones within the assembly have tailored magnetic properties to compensate for geometric field variations, creating locally optimized field conditions that collectively produce homogeneous overall field distribution at the isocenter
Solution Approach 2:
The invention employs asymmetric magnet assembly configurations where magnets are positioned and oriented in non-symmetric patterns. This asymmetry is deliberately designed to counterbalance field inhomogeneities that would otherwise arise from the geometric arrangement, achieving homogeneous field distribution through compensatory asymmetric placement
3Device complexity
If permanent magnets are positioned close to the test strip to reduce device size, then device complexity is reduced, but interference with reaction kinetics increases affecting assay accuracy
Solution Approach 1:
The magnetic assembly is designed to be movable relative to the test strip, allowing dynamic adjustment of the distance and orientation between the magnets and the sample. This enables the system to minimize device size while avoiding harmful magnetic interference during critical reaction phases by positioning magnets at optimal distances
Solution Approach 2:
The magnetic field application is implemented in periodic cycles rather than continuously. Magnets are positioned close to the test strip only during specific phases (such as particle capture or washing) when strong magnetic fields are beneficial, and retracted during reaction phases to avoid interfering with biochemical kinetics
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
Provides consistent and homogeneous magnetic field coverage for accurate assay results, reducing device size and power requirements, suitable for portable point-of-care testing.
Implementation Method 1
The capture antibody is attached to a magnetic particle with sufficient paramagnetic material content to be attracted and retained by an applied magnetic field
Implementation Method 2
magnetic particle with sufficient paramagnetic material content
Implementation Method 3
the pole piece comprises a cap at one end of the shaft which extends at least partially over a lateral surface of each of the at least two magnetic elements
Data Source
AI summary
A magnetic assembly for use in a device for conducting assays is disclosed. The magnetic assembly comprises a pole piece having a longitudinal shaft interposed between at least two magnetic elements, each of the at least two magnetic elements having a north magnetic pole and a south magnetic pole; the at least two magnetic elements being orientated such that each north magnetic pole or each south magnetic pole is aligned inwardly towards the shaft; and wherein the pole piece comprises a cap at one end of the shaft which extends at least partially over a lateral surface of each of the at least two magnetic elements. Also disclosed is a device for conducting assays and a method of operating the device.