AC Magnetization Measurement Using Mixed-Frequency Excitation
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Solution Overview
Problem
Conventional methods for measuring ac magnetization of magnetic fluids are limited by ambient signal interference, sub-harmonic effects, and high-level input voltage limitations, leading to unreliable output voltages at target frequencies.
Innovation Solution
The use of mixed-frequency excitation technology and a compensation mechanism in the electronic circuit, where two different frequencies are applied to the magnetic field and processed to isolate and amplify the target frequency component, reducing interference from sub-harmonic signals and ambient noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional single-frequency excitation is used, then the measurement system is simple, but the output voltage is unreliable due to sub-harmonic effects and ambient signal interference
Solution Approach 1:
The excitation signal is segmented into multiple frequency components (first frequency f1 and second frequency f2) instead of using a single frequency. This segmentation allows the target magnetization signal to appear at a unique combination frequency (f1+f2) that is distinct from sub-harmonics and ambient interference, thereby improving output voltage reliability
Solution Approach 2:
The measurement system transitions from single-frequency excitation to multi-frequency excitation, adding a frequency dimension to the excitation signal. This dimensional change creates a unique frequency signature (f1+f2) for the target signal, enabling reliable distinction from interference signals that occupy different frequency positions
2Measurement precision
If mixed-frequency excitation is used, then the target frequency component can be isolated, but the device complexity increases
Solution Approach 1:
The patent introduces a signal processing circuit as an intermediary that processes the mixed-frequency excitation signals. This intermediary contains compensation mechanisms that selectively amplify the target frequency component (f1+f2) while suppressing other frequency components, achieving precise target frequency isolation through the mediating action of the signal processing circuit
Solution Approach 2:
The system changes the frequency parameters of the excitation signal from a single frequency to multiple frequencies (f1 and f2). This parameter change enables the target magnetization signal to be distinguished at the combination frequency (f1+f2), improving measurement precision through frequency domain separation
3Measurement precision
If amplification is applied to enhance detection sensitivity, then the target signal is amplified, but sub-harmonic signals and ambient noise are also amplified
Solution Approach 1:
The signal processing circuit extracts only the target frequency component (f1+f2) from the mixed-frequency excitation signals through selective amplification. By taking out and amplifying only the specific frequency component corresponding to the target magnetization signal, the system enhances detection sensitivity without proportionally amplifying sub-harmonic signals and ambient noise that occupy different frequency positions
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 precise measurement of ac magnetization by isolating the target frequency component, enhancing detection sensitivity and reducing noise, thereby providing a reliable output for bio-molecular quantification.
Implementation Method 1
a co-axial solenoid unit driven by the first ac current and the second ac current to generate a first magnetic field and a second magnetic field
Implementation Method 2
a gradiometer-type pick-up solenoid disposed within the co-axial solenoid unit, wherein a sample is disposed in the pick-up solenoid for detection an ac magnetization of the sample
Implementation Method 3
magnetic fluid shows magnetization having frequencies of not only fo but also αfo under a weak ac magnetic field with frequency fo
Data Source
AI summary
Disclosed is an apparatus for measuring ac magnetization at mixture frequency. The apparatus includes an ac generating unit for generating at least a first current with a frequency f1 and a second current with a frequency f2. The apparatus further includes a co-axial solenoid unit, driven by the first and second ac currents, to generate a first magnetic field and a second magnetic field. A pick-up solenoid is for disposing sample for detecting an ac magnetization of the sample and multiple frequency-component signals corresponding to various frequency combinations of f1 and f2 are output. The apparatus further includes a signal processing circuit for receiving the frequency-component signals, where the signal processing circuit obtains the ac magnetization of the sample at a target frequency of (γTf1+βTf2), which γT and βT are positive integers and the frequency f1 and the frequency f2 are two different frequencies.