Application Cases

[Overview]

In this study, a power amplifier was used to build an experimental platform for a lead-free piezoelectric MEMS hydrophone. This experiment aims to provide theoretical and experimental support for the engineering application of high-reliability lead-free piezoelectric MEMS hydrophones, and to advance their practical deployment in fields such as marine environment monitoring and underwater target recognition.

Experiment Name: Key-Parameter Testing Experiment of Lead-Free Piezoelectric MEMS Hydrophones

Research Directions: Lead-free piezoelectric materials; AlScN piezoelectric thin film; MEMS hydrophone; magnetron sputtering; micro-nano fabrication; acoustic impedance matching; low-noise signal amplification; low-frequency underwater acoustic detection.

Experiment Objective: As a core device in emerging miniaturized and unmanned underwater detection systems, the performance of piezoelectric MEMS hydrophones directly determines the sensitivity and reliability of underwater detection systems. However, traditional lead-based piezoelectric materials are limited in wider application due to heavy-metal pollution. Although lead-free piezoelectric materials offer environmental advantages, their sensitivity in complex underwater acoustic environments, environmental adaptability, and self-noise suppression capability still require systematic study.

Test Equipment:

1. Reference (standard) hydrophone

2. Power amplifier

3. Programmable electronic switch

4. DSOX3014T digital oscilloscope

5. Preamplifier

6. Programmable filter

7. Stainless-steel calibration cavity (standing-wave tube)

8. Custom high-precision rotary arm, together with a host computer and signal-acquisition peripherals

Figure 1. Schematic of the experimental platform

Experiment Procedure: The experiment adopted the “standing-wave field test method (comparison calibration method)”. The self-developed lead-free piezoelectric MEMS hydrophone and a standard hydrophone were simultaneously suspended vertically in a stainless-steel calibration cavity filled with seawater. A ±7 V DC bias was applied to the hydrophone under test. The system signal source drove the transmitting transducer to form a planar standing-wave sound field inside the cavity. With the immersion depth of both hydrophones fixed, the open-circuit voltages of the test hydrophone and the standard hydrophone were acquired and recorded, and the sound-pressure sensitivity at different frequencies was calculated by substituting the data into the calibration formula, completing the full-band sensitivity test.

Experiment Results: The self-developed lead-free piezoelectric MEMS hydrophone achieved an average sensitivity of −168 dB (re 1 V/µPa). In the target low-frequency band (10 Hz–100 Hz), the sensitivity was better than −167 dB (re 1 V/µPa). The in-band sensitivity curve showed a maximum fluctuation of ±5 dB and an average fluctuation of less than ±3 dB; the non-uniformity approached the national practical standard for measurement hydrophones. The low-frequency sensitivity performance was superior to that of similar domestic lead-free piezoelectric MEMS hydrophones.

Product Advantages of Aigtek Amplifiers in This Application:

1. High-power and high-current drive capability — Effectively drives the transmitting transducer to establish a stable planar sound field across the full frequency band.

2. Wide bandwidth and flat response — Accurately ensures the accuracy of low-frequency sensitivity calibration.

3. Low distortion and high output stability — Guarantees repeatability of calibration data and long-term reliable system operation.

[Recommended Product]: ATA-3000 Series Power Amplifier

Figure: Specifications of the ATA-3000 series power amplifier

The experimental materials in this article were compiled and published by Xi'an Aigtek Electronics. Aigtek has become an instrumentation supplier with a broad product portfolio and considerable scale in the industry; demonstration units are available with free trial support. Xi'an Aigtek Electronics is a high-tech enterprise specializing in the R&D, manufacturing, and sales of electronic test instruments including power amplifiers, high-voltage amplifiers, power signal sources, preamplifiers (low-noise signal amplifiers), high-precision voltage sources, and high-precision current sources.