A Fiber Bragg Grating-Based Sensor for Passive Cavitation Detection at MHz Frequencies

Area of Science:

• Biomedical Engineering
• Optical Sensing
• Acoustics

Background:

• Fiber Bragg gratings (FBGs) are explored as alternatives to piezoelectric sensors for ultrasound detection.
• Existing research lacks quantitative data on FBG performance in the MHz frequency range crucial for biomedical ultrasound.
• Electromagnetic interference (EMI) immunity is a key advantage of FBGs in sensitive applications.

Purpose of the Study:

• To quantitatively evaluate Fiber Bragg grating (FBG) sensor performance for detecting MHz-frequency ultrasound.
• To assess the feasibility of using FBGs for measuring passive cavitation signals.
• To characterize FBG sensitivity, linearity, and repeatability at 1, 5, and 10 MHz.

Main Methods:

• FBG sensor performance was assessed for ultrasound detection at 1, 5, and 10 MHz.
• Sensitivity, linearity (R-squared), and repeatability (coefficient of variation) were measured.
• Passive cavitation signals from SonoVue microbubbles were measured using the FBG sensor.

Main Results:

• FBG sensors demonstrated high sensitivity (0.769–0.99 V/MPa) across 1-10 MHz ultrasound frequencies.
• Excellent linearity (R-squared ≥ 0.975) and repeatability (CV < 5.5%) were observed.
• Passive cavitation emissions, including subharmonic and ultraharmonic peaks, were successfully detected.

Conclusions:

• FBGs show significant potential as high-performance sensors for MHz-frequency ultrasound applications.
• FBGs are suitable for passive cavitation detection (PCD), offering advantages over traditional sensors.
• This work provides crucial quantitative data for FBG sensor implementation in biomedical ultrasound.