Magnetic Particle Spectroscopy Phase Detection
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Solution Overview
Problem
Existing methods for measuring sample properties based on the dynamic magnetic response of magnetic nanoparticles are limited by the need for accurate measurement control, long acquisition times, and require sophisticated hardware and trained personnel.
Innovation Solution
A method involving the application of a time-varying magnetic excitation field and a magnetic field gradient to drive magnetic particles into a non-linear magnetization response regime, allowing for the detection of phase shifts in higher harmonics, which can indicate minor changes in sample properties such as hydrodynamic diameter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If accurate measurement control is used to resolve signal amplitudes, then measurement precision is improved, but measurement time increases and device heating occurs
Solution Approach 1:
The patent changes the measurement parameter from signal amplitude to phase of higher harmonics. This parameter transformation allows rapid measurement without the need for long acquisition times and sophisticated amplitude resolution, while still providing sensitive detection of nanoparticle properties through phase shifts in the 3rd and higher harmonics of the magnetization response.
2Measurement precision
If sophisticated hardware and data processing are used to improve measurement precision, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent simplifies the measurement approach by using phase detection of higher harmonics instead of complex amplitude measurements. This parameter change reduces the need for sophisticated hardware and data processing while maintaining high measurement precision for detecting sample properties such as viscosity, temperature, and nanoparticle clustering.
3Measurement precision
If drive currents are increased to improve signal strength, then signal amplitude is improved, but temperature drift and device heating occur
Solution Approach 1:
The patent changes from measuring signal amplitude to measuring phase of higher harmonics. This parameter transformation allows for sufficient signal detection without requiring high drive currents, thereby avoiding device heating and temperature drift while maintaining the ability to detect sample properties accurately.
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 method enables fast and robust sample characterization by detecting minor changes in Brownian relaxation characteristics of magnetic particles, allowing for rapid measurement of sample properties without the need for precise amplitude measurements.
Implementation Method 1
applying a time-varying magnetic excitation field, the excitation field having an excitation amplitude and an excitation frequency, such that the magnetic particles are driven into a non-linear magnetization response regime
Implementation Method 2
The magnetic moments of MNPs follow the time-varying external field directions through a combined Néel and Brownian relaxation mechanism. The Brownian relaxation process is dominant for single-core iron oxide MNPs with core sizes above 20 nm and can reflect the degree of freedom of physical rotational motion of the MNPs.
Implementation Method 3
Magnetic particle spectroscopy (MPS) is a quite young technology for the characterization of MNPs. It uses an oscillating magnetic field of a sufficient field strength to drive a MNP ensemble periodically into a non-linear magnetization response.
Data Source
AI summary
A method for measuring a modified property of a sample comprising magnetic particles in suspension using time variable magnetic fields, wherein the method comprises applying a time-varying magnetic excitation field, the excitation field having an excitation amplitude and an excitation frequency, and an offset magnetic field to the sample, such that the magnetic particles are driven into a non-linear magnetization response regime; recording a non-linear magnetization response of the sample for obtaining a signal metric indicative for a phase of a higher harmonic with respect to the excitation frequency in the non-linear magnetization response; and determining a measurement signal indicative of the modified property, the measurement signal being based on the signal metric obtained for the sample and the same signal metric obtained for a reference sample without the modified property, the reference sample also comprising the magnetic particles in suspension.