A piezoelectric, flexural-disk, neutrally buoyant, underwater accelerometer

Area of Science:

• Engineering
• Materials Science
• Oceanography

Background:

• Underwater accelerometers are crucial for marine research and monitoring.
• Existing sensors may face challenges with buoyancy, pressure, and noise in aquatic environments.
• Development of robust, sensitive accelerometers is essential for accurate data acquisition.

Purpose of the Study:

• To design and characterize a novel piezoelectric accelerometer for reliable underwater operation.
• To achieve neutral buoyancy and a compact form factor for the sensor.
• To evaluate the sensor's sensitivity, noise floor, and resonance frequency.

Main Methods:

• Fabrication of a flexural-disk accelerometer using lead zirconate-titanate (PZT-5A) disks bonded to an aluminum substrate.
• Encasing the sensor in syntactic foam for neutral buoyancy within an aluminum housing.
• Characterization of sensitivity, capacitance, resonance frequency, and spectral noise-equivalent acceleration floor.

Main Results:

• The accelerometer utilizes two PZT-5A disks on an aluminum substrate, housed in a neutrally buoyant, foam-enclosed aluminum casing.
• Key performance metrics include a sensitivity of -42 dB re 1 V-s(2)/m, capacitance of 5.0 nF, and resonance frequency of 11 kHz.
• The spectral noise-equivalent acceleration floor is approximately -171 dB re 1 m/s(2)-√Hz at 5 kHz when paired with a specific preamplifier.

Conclusions:

• The developed piezoelectric accelerometer is suitable for underwater use, offering neutral buoyancy and a compact design.
• The sensor demonstrates good sensitivity and a low noise floor, making it effective for measuring acceleration in marine settings.
• This accelerometer provides a valuable tool for various underwater sensing applications requiring precise motion detection.