EPR Detection Using Frank Sequence and Crossed Loop Resonator
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Solution Overview
Problem
Electron Paramagnetic Resonance (EPR) imaging faces challenges due to short electron spin relaxation times, requiring rapid detection and high power levels, which can lead to excessive RF/microwave power absorption and compliance issues with FDA regulations.
Innovation Solution
The use of a Frank sequence and a crossed loop resonator to generate and isolate low-power microwave signals, allowing for efficient detection of electron spins within a short time frame, reducing the 'dead time' and minimizing power absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high power levels are used to excite electron spins in EPR imaging, then detection sensitivity is improved, but power absorption by the object increases leading to regulatory compliance issues
Solution Approach 1:
The patent applies periodic pulse sequences (Frank sequences) to excite electron spins, replacing continuous high-power excitation with timed periodic pulses. This allows accumulation of signal over multiple pulses while limiting total power absorption, resolving the contradiction between detection sensitivity and power absorption constraints
Solution Approach 2:
The patent changes the temporal parameters of excitation by using variable pulse widths and intervals in the Frank sequence, optimizing the balance between signal generation and power absorption. By adjusting pulse duration and repetition timing, the system achieves sufficient detection sensitivity while maintaining power absorption within regulatory limits
2Reliability
If rapid detection is implemented to account for short electron spin relaxation times, then signal capture is improved, but dead time in the system increases
Solution Approach 1:
The patent uses preliminary action by preparing the spin system through a sequence of preparatory pulses before the actual detection pulse. The Frank sequence pre-aligns and conditions the electron spins, so that when the detection pulse arrives, the signal is already optimized for capture, reducing the critical dead time
Solution Approach 2:
The patent implements rapid switching and detection mechanisms that skip through the dead time period by using hard pulse sequences with minimal relaxation periods. The system rushes through the necessary detection window efficiently, capturing the signal before relaxation occurs while minimizing idle dead time
3Use of energy by stationary object
If continuous wave excitation is used in EPR, then power consumption is reduced, but detection precision deteriorates due to inability to resolve short relaxation times
Solution Approach 1:
The patent transforms continuous wave excitation into periodic pulsed excitation using Frank sequences. This maintains lower average power consumption compared to continuous excitation while providing sufficient temporal resolution to detect short electron spin relaxation times, thus resolving the contradiction between power consumption and detection precision
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 enables EPR imaging with significantly reduced power levels, below 50 Watts, while maintaining effective detection of electron spins, thus addressing the limitations of short relaxation times and compliance with regulatory standards.
Implementation Method 1
an excitation signal generator configured to generate an excitation signal... applying the continuous wave excitation signal to an object... exciting the object with a magnetic field
Implementation Method 2
a crossed loop resonator configured to isolate a detection signal produced by the excitation signal exciting an object with a magnetic field
Implementation Method 3
detecting electron spins using electron paramagnetic resonance... detect electron spins of the object using the detection signal
Data Source
AI summary
Various systems and methods for detecting electron spins using electron paramagnetic resonance are described. An excitation signal generator configured to generate an excitation signal of varying amplitude and phase as compared to a reference signal may be present. A crossed loop resonator configured to isolate a detection signal produced by the excitation signal exciting an object with a magnetic field may also be preset. Further, a detection device configured to detect electron spins of the object using the detection signal isolated by the crossed loop resonator may be present.