Optical Fiber Bragg Grating Detector for Intravascular Imaging
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Solution Overview
Problem
Current ultrasound detectors, particularly piezo-electric detectors, face challenges in sensitivity and miniaturization for intravascular multispectral optoacoustic imaging, and are vulnerable to electromagnetic radiation, limiting their effectiveness in thermoacoustic imaging applications.
Innovation Solution
An ultrasound detector utilizing an optical waveguide with a π-phase-shifted Bragg grating that includes a localized defect in periodicity, allowing for enhanced acoustic sensitivity and resistance to environmental changes, coupled with a wideband pulsed interrogation light source for improved detection and multiplexing capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If piezo-electric detectors are miniaturized for intravascular imaging, then the detector size is reduced allowing use in coronary arteries, but the acoustic sensitivity is diminished
Solution Approach 1:
The patent replaces piezo-electric mechanical detection with optical detection using a fiber optic sensor. The fiber optic sensor detects acoustic waves through optical interference patterns caused by acoustic-induced refractive index changes, eliminating the need for mechanical piezo-electric elements and enabling miniaturization without sensitivity loss.
Solution Approach 2:
The patent changes the detection parameter from electrical voltage (piezo-electric) to optical interference patterns. By monitoring phase changes in light caused by acoustic-induced refractive index variations, the system achieves high sensitivity in a miniaturized format suitable for intravascular imaging.
2Power
If high energy optical pulses are used to generate sufficient acoustic signal, then the acoustic signal magnitude increases, but the average laser power exceeds the tissue damage threshold
Solution Approach 1:
The patent replaces piezo-electric detection with optical detection, enabling the use of lower energy optical pulses. The optical fiber sensor's high sensitivity allows detection of weaker acoustic signals generated by lower energy pulses, thereby reducing the risk of tissue damage while maintaining adequate signal strength for imaging.
3Measurement precision
If piezo-electric detectors are used for thermoacoustic imaging, then the detectors can measure acoustic fields, but they are vulnerable to electromagnetic radiation from high intensity optical pulses and RF radiation
Solution Approach 1:
The patent replaces piezo-electric detectors with optical fiber sensors that detect acoustic waves through optical interference. Since optical fibers are dielectric materials, they are inherently immune to electromagnetic radiation from optical pulses and RF fields, eliminating the vulnerability while maintaining acoustic detection capability.
4Reliability
If optical detection schemes are used instead of piezo-electric detectors, then the detectors are not sensitive to external electromagnetic fields, but they fail to achieve the bandwidth and sensitivity of piezo-electric technology
Solution Approach 1:
The patent changes the detection parameter to optical interference patterns and uses a swept-wavelength laser source to scan through a wide spectral range. This approach provides both electromagnetic field immunity and high sensitivity with wide bandwidth, as the swept-wavelength technique allows detection across multiple frequencies simultaneously.
Solution Approach 2:
The patent employs periodic sweeping of the laser wavelength across a broad spectrum. This periodic modulation of the optical frequency allows the system to probe multiple acoustic frequencies sequentially, achieving wide bandwidth detection while maintaining high sensitivity through coherent detection methods.
5Speed
If wideband continuous-wave source interrogation is used with Fiber Bragg Gratings, then the detection bandwidth is increased, but the inherent noise from incoherent light source severely limits sensitivity
Solution Approach 1:
The patent replaces continuous-wave interrogation with periodic swept-wavelength pulsed laser excitation. The swept-wavelength technique modulates the optical frequency in a controlled periodic manner, enabling wideband detection while maintaining coherence throughout the measurement process, thus avoiding the noise problems of incoherent continuous-wave sources.
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 solution provides significantly improved acoustic sensitivity and faster imaging speeds, overcoming the limitations of current detectors by concentrating the localized-light resonance portion at the defect, enabling more efficient and non-invasive optoacoustic or thermoacoustic imaging.
Implementation Method 1
at least one Bragg grating created in the optical waveguide, wherein the at least one Bragg grating includes a localized defect in periodicity so that a localized-light resonance portion is formed around the defect
Implementation Method 2
Optical detection schemes are based on the photoelastic effect, where stress or strain in the optical medium leads to changes in its refractive index
Implementation Method 3
an optical waveguide and at least one Bragg grating created in the optical waveguide
Data Source
AI summary
An ultrasound detector adapted for ultrasound detection with medical applications includes an optical waveguide, and at least one Bragg grating, created with a predetermined refractive index modulation amplitude in the optical waveguide, wherein the at least one Bragg grating includes a localized defect in periodicity so that a localized-light resonance portion is formed around the defect, and the localized-light resonance portion has spectral properties capable of being modulated in response to an ultrasound oscillation, wherein the optical waveguide is a non-amplifying optical medium, and the refractive index modulation amplitude is selected such that the localized-light resonance portion is concentrated at the defect in periodicity and the ultrasound oscillation can be sensed by the at least one Bragg grating with an acoustic sensitivity most of which being obtained over the localized-light resonance portion.