Magnetic Particle Quantification via Modulated EPR
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for quantifying magnetic particles, such as paramagnetic particles, using electron paramagnetic resonance (EPR) face challenges in accurately determining a wide range of concentrations and require improvements for precise quantification and efficient imaging.
Innovation Solution
A method and system that apply a first time-varying magnetic field and a second RF field orthogonal to the first, allowing for the measurement of resultant magnetization and subsequent discrete Fourier transform to determine specific frequency components, enabling accurate quantification of magnetic particles by calculating power and voltage from these components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional EPR methods are used for quantifying magnetic particles, then measurement capability is provided, but measurement precision and accuracy over a wide concentration range are insufficient
Solution Approach 1:
The patent applies periodic modulation to the static magnetic field B0, transforming it into a time-varying field with frequency fB0. This periodic action creates amplitude-modulated signal components at frequencies fB1±nfB0 that are proportional to particle quantity, enabling accurate quantification across wide concentration ranges while maintaining high measurement precision through frequency-domain analysis
Solution Approach 2:
The patent changes the parameter of the magnetic field from static to time-varying by applying periodic modulation at frequency fB0. This parameter change transforms the EPR signal into an amplitude-modulated signal where the modulation depth carries quantitative information about particle concentration, resolving the contradiction between precision and range
2Reliability
If DC magnetic fields are used for magnetic polarization, then EPR detection is enabled, but signal amplification and noise reduction are limited
Solution Approach 1:
By applying periodic modulation to the magnetic field B0, the patent transforms the static EPR signal into an amplitude-modulated signal. This periodic action enables signal amplification through the modulation process and allows noise reduction by shifting the signal to higher frequency components (fB1±nfB0) where noise contributions are reduced, thereby improving reliability while enhancing power
Solution Approach 2:
The patent introduces an intermediary modulation process that acts on the EPR signal. The periodic modulation serves as an intermediary mechanism that amplifies the signal through amplitude modulation and simultaneously filters noise by operating at frequency components where environmental and electronic noise contributions are minimized
3Ease of manufacture
If parallel transmission and receiving coils are used, then simple geometry is achieved, but signal amplification is reduced
Solution Approach 1:
The patent employs asymmetric coil geometry where the transmission coil and receiving coil are oriented non-parallel to each other. This asymmetry increases the magnetic coupling between coils and enhances signal amplification while maintaining manufacturing simplicity through standard coil winding techniques at specific angles
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
This approach allows for sensitive and accurate determination of magnetic particle quantities over several orders of magnitude, from 1 nanogram to 4500 micrograms in a volume, irrespective of particle size or shape, with enhanced signal amplification and reduced noise contributions.
Implementation Method 1
applying a first magnetic field (B0) to said volume for magnetizing said magnetic particles, the first magnetic field (B0) being a time-varying field
Implementation Method 2
applying to said volume a second magnetic field (B1) not parallel to the first magnetic field (B0) for causing precession of the magnetic moment of the magnetized particles, the second magnetic field being an RF field having a second frequency (fB1) chosen substantially equal to the Larmor-frequency (fL)
Implementation Method 3
measuring a resultant magnetization (M) originating from the volume by obtaining a voltage signal being representative for the resultant magnetization using a sensing element
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
Quantification of a particular element comprised in magnetic particles enclosed in a volume is described. Applying a first time-varying magnetic field, Bo(t) to said volume, having a first magnitude and a first frequency, fBo and applying a second time varying magnetic field, B1(t), not parallel with the first magnetic field Bo(t) for causing precession of the magnetized particles is performed. The second magnetic field is an RF field having a second frequency, fB1 equal to the Larmor-frequency, fL of said particular element. Thereafter the resultant magnetization, M(t), originating from the volume and modulated by the time-varying field is measured, and at least one frequency component fB1±nfBO,n=1,3,5,... of the resultant magnetization is determined. A power and/or voltage of the at least one frequency component is calculated and a quantity of the magnetic particles enclosed in the volume is determined based thereon.