Capacitive Low-Frequency Hydrophone Based on Micronanostructured Iontronic Hydrogel for Underwater Monitoring

Area of Science:

• Acoustic Engineering
• Materials Science
• Sensor Technology

Background:

• Hydrophones are vital for underwater detection but struggle with low sensitivity and poor signal-to-noise ratio (SNR) for low-frequency signals.
• Existing technologies face limitations in accurately detecting subtle underwater acoustic phenomena.

Purpose of the Study:

• To develop a highly sensitive capacitive hydrophone (CH) for enhanced low-frequency underwater sound detection.
• To investigate the efficacy of a carbon nanotube (CNT) integrated hydrogel in improving sensor performance.

Main Methods:

• Fabrication of a capacitive hydrophone (CH) using a latex film/silver electrode and a structured hydrogel electrolyte.
• Integration of a carbon nanotube (CNT) topology network within a pyramid microarray in the hydrogel to enhance electric double layer (EDL) formation.
• Testing the CH's sensitivity and SNR across a broad frequency range (20-800 Hz), particularly in the low-frequency band (20-125 Hz).

Main Results:

• The CH achieved a receiving sensitivity of -159.7 dB in the 20-125 Hz band, outperforming a commercial hydrophone by 33.29 dB.
• Demonstrated exceptional low-pressure sensitivity and a superior SNR, enabling detection of sound waves as faint as 0.3 Pa.
• The CNT-enhanced EDL sensing mechanism significantly improved sensitivity and precision.

Conclusions:

• The developed CNT-enhanced capacitive hydrophone offers a significant advancement for low-frequency underwater acoustic detection.
• This technology shows great potential for applications in sonar systems, maritime vessel monitoring, and underwater soundscape analysis.
• The CNT-enhanced EDL sensing mechanism provides a promising pathway for future high-performance hydrophone designs.