FBG Sensor Unit for Stable Heartbeat Detection in MRI Imaging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for monitoring heartbeats during medical imaging, such as those using electrocardiogram, pulse wave measurement, and electromagnetic waves, suffer from mental and temporal burdens on subjects and operators, inaccurate peak detection, and drift issues due to subject movement, especially in MRI environments.
Innovation Solution
A sensor unit with a fiber Bragg grating sensor fixed to a stiff member and covered by a cover with a hole, featuring a contact assisting member and elastic elements, to stabilize the sensor and maintain contact with the subject, reducing movement and drift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electrodes with conductive gel are installed on the skin to measure electrocardiogram waveform, then heartbeat monitoring accuracy is improved, but mental and temporal burdens on subject and operator increase
Solution Approach 1:
The patent replaces the mechanical electrode-gel-skin contact system with an optical fiber-based FBG sensor system. The FBG sensor detects heartbeat through optical wavelength shifts caused by skin surface displacement, eliminating the need for conductive gel and complex electrode installation while maintaining measurement accuracy.
Solution Approach 2:
The patent introduces an optical fiber as an intermediary medium between the subject's skin and the detection system. The FBG sensor embedded in the optical fiber detects skin surface changes through optical wavelength modulation, serving as a non-intrusive mediator that avoids direct electrical contact and reduces installation burden.
2Measurement precision
If FBG sensor is attached directly to skin surface to detect pulse wave, then detection sensitivity is improved, but sensor stability deteriorates due to subject movement
Solution Approach 1:
The patent embeds the FBG sensor within a multi-layered sensor unit structure that includes a flexible substrate, adhesive layer, and protective coating. This nested configuration protects the sensitive optical fiber while maintaining contact with the skin surface, ensuring both detection sensitivity and sensor stability during subject movement.
Solution Approach 2:
The patent uses a flexible substrate and thin film structures to mount the FBG sensor. These flexible components conform to the skin surface and move with the subject, maintaining stable contact without restricting natural movement, thereby preserving both sensitivity and stability.
3Adaptability or versatility
If optical fiber with multiple FBG sensors is used to detect pulse waves at multiple locations, then measurement capability is improved, but device complexity increases
Solution Approach 1:
The patent designs a universal sensor unit that can be applied to multiple measurement locations on the body. Each sensor unit contains an FBG sensor that can detect pulse waves at different anatomical sites, providing multi-functional capability without requiring different sensor types or complex configuration changes.
Solution Approach 2:
The patent divides the measurement system into multiple independent sensor units, each containing an FBG sensor. These modular segments can be independently attached to different body locations, allowing versatile multi-point measurement while keeping each individual sensor unit simple and easy to handle.
4Stability of the object's composition
If sensor is fixed rigidly to prevent movement, then sensor stability is improved, but detection accuracy deteriorates due to inability to follow skin surface changes
Solution Approach 1:
The patent employs a dynamic mounting system where the sensor unit is attached with controlled flexibility. The adhesive layer and flexible substrate allow the sensor to dynamically follow skin surface changes during heartbeat and breathing while maintaining overall positional stability, achieving both stability and accuracy through dynamic adaptation.
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
The sensor unit effectively detects heartbeats with high accuracy by minimizing movement and drift, allowing precise synchronization with MRI imaging without the need for direct skin contact and reducing mental and temporal burdens.
Implementation Method 1
an optical fiber in which a plurality of FBG sensors are arranged in series is used in a case where pulse waves at a plurality of locations are detected using the FBG sensors. The plurality of FBG sensors have different Bragg wavelengths from each other.
Implementation Method 2
The plurality of FBG sensors have different Bragg wavelengths from each other. In the optical fiber sensor system, light incident on the optical fiber is light in a band including the Bragg wavelength of the FBG sensor, and the optical signal of each of the FBG sensors is separated and detected.
Data Source
AI summary
Provided are a sensor unit and a medical image capturing apparatus in which movement of the sensor unit caused by movement of a subject is suppressed. The sensor unit is attached to a surface on which a subject is placed and detects a heartbeat of the subject, and includes an FBG sensor that is provided with one or more sensor elements for detecting the heartbeat of the subject, a fixing member that fixes a side of the FBG sensor opposite to a side facing the subject and that has a surface on which the FBG sensor is fixed, the surface having a predetermined stiffness, and a cover that covers the side of the FBG sensor facing the subject and that has a structure in which a cover hole is formed at a position corresponding to the sensor element on a surface of the side facing the subject.