Orthogonal Receive Coil for In Vivo Sensor Signal Isolation
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Solution Overview
Problem
Existing in vivo sensing technologies face challenges in accurately determining characteristics like pressure and quality factors within the body due to interference from large oscillation signals and difficulty in separating small receive signals from the RF probe's frequency measurements.
Innovation Solution
The method involves generating a transmit field to induce a response signal in an in vivo sensor, with a receive coil oriented orthogonally to the transmit coil to minimize coupling and enhance signal isolation, allowing for precise measurement of magnetic coupling and determination of resonant frequency and quality factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single RF coil is used in the grid-dip oscillator approach, then device complexity is reduced, but measurement precision deteriorates due to difficulty in separating small receive signals from large oscillation signals
Solution Approach 1:
The single RF coil is segmented into two separate coils: a transmit coil for generating the oscillating RF current and a receive coil for detecting the sensor response. This segmentation allows the transmit and receive functions to be performed independently, enabling the small receive signal to be separated from the large transmit signal, thereby improving measurement precision while maintaining relatively simple device structure.
Solution Approach 2:
The receive coil is extracted and oriented orthogonally to the transmit coil to specifically extract the sensor response signal while rejecting the large oscillation signal from the transmit coil. This spatial extraction enables the small receive signal to be isolated from the dominant transmit signal, resolving the signal separation problem.
2Measurement precision
If the receive coil is oriented orthogonally to the transmit coil, then signal isolation is improved, but coupling measurement becomes more complex
Solution Approach 1:
The receive coil is oriented in a dimension orthogonal to the transmit coil's orientation. By utilizing the third spatial dimension (orthogonal orientation), the patent achieves effective signal isolation where the magnetic field of the transmit coil does not couple with the receive coil, thereby improving signal isolation without requiring complex shielding or filtering mechanisms.
Solution Approach 2:
The sensor itself acts as an intermediary that couples the transmit coil and receive coil. The transmit coil induces current in the sensor, which then generates a magnetic field detected by the receive coil. This intermediary mechanism enables signal transfer while maintaining orthogonal orientation and minimizing direct coupling between the coils.
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 improves signal isolation by up to 100 dB, enabling the detection of small implanted sensors and providing accurate measurements of characteristics like pressure and quality factors, reducing noise floor and enhancing the sensitivity of in vivo sensing.
Implementation Method 1
An oscillating RF current flows through an RF coil, inducing currents in the inductance coil of a nearby sensor
Implementation Method 2
The loading effect of the sensor on the RF transmit coil results in a decrease or 'dip' in the phase response of the transmitter current and the frequency
Implementation Method 3
A receive coil, oriented as to interact with signals having a second orientation that is substantially orthogonal to first orientation
Data Source
AI summary
Methods and systems are provided for determining a characteristic of an in vivo sensor. A transmit field, operative to induce a response signal in an associated in vivo sensor, is generated at a transmitting component having an associated orientation. The response signal is received at a receiving component, having an associated orientation. The coupling between the transmitting component and the receiving component is measured. The associated orientation of at least one of the transmitting component and the receiving component is rotated as to reduce the measured coupling.