Design Of Hydrophone Research Articles

Design and Implementation of a Four-Unit Array Piezoelectric Bionic MEMS Vector Hydrophone.

High-performance vector hydrophones have been gaining attention for underwater target-monitoring applications. Nevertheless, there exists the mutual constraint between sensitivity and bandwidth of a single hydrophone. To solve this problem, a four-unit array piezoelectric bionic MEMS vector hydrophone (FPVH) was developed in this paper, which has a cross-beam and a bionic fish-lateral-line-nerve-cell-cilia unit array structure. Simulation analysis and optimization in the design of the bionic microstructure have been performed by COMSOL 6.1 software to determine the structure dimensions and the lead zirconate titanate (PZT) thin film distribution. The FPVH was manufactured using MEMS technology and tested in a standing wave bucket. The results indicate that the FPVH has a sensitivity of up to -167.93 dB@1000 Hz (0 dB = 1 V/μPa), which is 12 dB higher than that of the one-unit piezoelectric MEMS vector hydrophone (OPVH). Additionally, the working bandwidth of the FPVH reaches 20 Hz~1200 Hz, exhibiting a good cosine curve with an 8-shape. This work paves a new way for the development of multi-unit piezoelectric vector hydrophones for underwater acoustic detectors.

Design and Implementation of a Multi-Function Hydrophone for Underwater Acoustic Application

In recent years, underwater acoustic applications have attracted much attention, for example, for underwater environmental monitoring, underwater exploration, etc. Hydrophones play a particularly important role. Although hydrophone design has been in multifarious application forms, it still needs to consider increasing demand for low-cost, low-consumption, and multiple-function devices, as well as issues around miniaturization, lossless data collection, etc. In this paper, we design a compact underwater acoustic device that has the capability of underwater acoustic signal storage, underwater acoustic signal transmission via the Internet, and decoding based on the direct sequences spread spectrum (DSSS). The key problem is how to implement multiple functions in only one micro-controller unit (MCU). The hardware and software of the proposed multi-function hydrophone are described in detail. In particular, the MCU, the pre-amplifier with gain control, and the analog-to-digital integrated chip are introduced. Moreover, underwater acoustic data storage, underwater acoustic transmission, and the DSSS receiver are depicted in terms of software. The different functions of the hydrophone are verified in sea trial experiments. The results show that the proposed multi-function hydrophone is able to sample underwater acoustic data at high quality. In addition, to demonstrate configurable parameters, the DSSS receiver with different carrier frequencies is provided. The proposed multi-function hydrophone realizes zero bit error rate (BER) when carrier frequency fc=9 kHz, and the BER with 10−3 order of magnitude when carrier frequency fc=15.5 kHz. The results show that the proposed multi-function hydrophone has great potential to explore the ocean.

Design and analysis of a flexible hydrophone based on PVDF with aluminum film substrate and PDMS encapsulation

Unmanned underwater vehicles (UUVs) need hydrophones for underwater acoustic sensing. However, previous hydrophones were rigid in shape and unable to realize conformal installation. In this paper, a flexible hydrophone with great installation adaptability was presented. Polyvinylidene fluoride (PVDF) piezoelectric film was applied as the transducing material. A flexible aluminum film was selected as the substrate. These two films were sandwiched by polydimethylsiloxane (PDMS) layers. Finite element simulation revealed that the sensitivity and bandwidth of the hydrophone were enhanced by using the aluminum film substrate. The sensing performance improvement was ascribed to the suppressed in-plane stress of the PVDF film. Prototypes were fabricated and tested. The fabricated hydrophone exhibited a sensitivity of −211 dB (ref. 1 V/μPa) at 500 Hz. It owned a 20–500 Hz working frequency range and an omnidirectional pattern. Besides, the sensitivity difference caused by shape changes was within 2.3 dB. Furthermore, the hydrophone showed good waterproofing ability.

Simulation Study on Optimization Design of MEMS Hydrophone Based on AlN Film

In this paper, simulation study on optimization design of MEMS hydrophone based on AlN (Aluminum Nitride) film is carried out. Based on the theory of elastic mechanics and sound-solid coupling effect, the effect of film shape on the sensitivity and frequency response of the device is studied firstly. Results show that a square shape is beneficial to improving the overall performance of the device. The effects of piezoelectric film thickness and radius on the device performance are studied consequently. Results show that increasing the piezoelectric film radius significantly improves the device sensitivity. Finally, the effects of sandwiched and unequal-thickness piezoelectric structures on the device performance are investigated. It is found that unequal-thickness piezoelectric structures can remarkably improve the device performance. Results of this paper would support the performance improvement of MEMS hydrophones based on AlN film in future research work.

Design and Fabrication of Hollow Mushroom-Like Cilia MEMS Vector Hydrophone

Vector hydrophone is the core equipment of underwater acoustic detection. Aiming at the problem of low sensitivity and short detection distance of existing vector hydrophone. In this paper, a hollow mushroom-like cilia sensitive structure is designed to optimize the hydrophone sensitive unit. The optimal size of the hollow mushroom-like cilia MEMS vector hydrophone (MCVH) microstructure was determined by COMSOL5.6 simulation. The hollow structure is adopted, which not only ensures the working bandwidth of the hydrophone is 20Hz-1000Hz, but also improves the sensitivity of the hydrophone by increasing the receiving area of the sound wave. The test results show that the hollow structure has obvious "8" directivity, and the pit depth of the "8" directivity larger than 40dB at 315Hz. Meantime, the sensitivity of MCVH can reach -180.9dB at 1000Hz. Compared with Ciliary MEMS vector hydrophone(CVH), the sensitivity is improved by 16.8dB.

Design and implementation of Crossed-circle MEMS ciliary vector hydrophone

MEMS ciliary vector hydrophone is used for underwater low-frequency acoustic signal testing, but it is limited by mutual inhibition of bandwidth and sensitivity. A crossed-circle bionic vector hydrophone is proposed in this paper. It uses two circular structures to increase receiving area of sound waves and improve sensitivity. At the same time, it improves working bandwidth of the hydrophone by reducing thickness of circular structure and adopting hollow cylinder. In this paper, COMSOL simulation software was used to carry out simulation and analysis of stress distribution and natural frequency, and determine the optimal size of crossed-circle structure. Experiments show that sensitivity of the hydrophone was measured to reach −184.5 dB@1250 Hz（0dB = 1 V/μPa）, and the working bandwidth was 20–1250 Hz, the sensitivity reaches −186.7 dB at 1000 Hz, 10.4 dB higher than that of single-cylinder structure. The depth of pit exceeds 30 dB at 315 Hz and 630 Hz, indicating that the hydrophone has excellent dipole directivity.

Design and Characterization of an Aluminum Nitride-Based MEMS Hydrophone With Biologically Honeycomb Architecture

In this article, we present a high-performance aluminum nitride (AlN)-based microelectromechanical system (MEMS) hydrophone sensor, in which the sensing cells are designed and arranged as an innovative honeycomb architecture for achieving large acoustic pressure sensitivity and high fill-factor. An 8×9 array of 360 μm in characteristic size, 0.92-MHz MEMS hydrophone sensor is developed based on an AlN-on-cavity silicon-on-insulator (CSOI) platform. The size of the MEMS hydrophone sensor is 3.2 mm ×3.2 mm. The MEMS hydrophone sensor and its preamplification circuit are integrated on a printed circuit board and packaged together with an acoustically transparent material, in order to meet the stringent requirements of underwater applications. The packaged MEMS hydrophone is fully characterized through using an industry-standard hydrophone calibration instrument. The MEMS hydrophone achieves an acoustic pressure sensitivity of -178 dB (re: 1 V/ μ Pa), with a maximum nonlinearity of 0.1%, and a noise resolution of 58.7 dB (re: 1 μPa/Hz). The measurement results show that the reported MEMS hydrophone sensor with bioinspired honeycomb structure is compared favorable with advanced commercially available bulky hydrophones.

Design and Implementation of a Composite Hydrophone of Sound Pressure and Sound Pressure Gradient.

The bionic cilium MEMS vector hydrophone has the characteristics of low power consumption, small volume, and good low-frequency response. Nevertheless, there exists the problem of left–right ambiguity in the azimuth estimation of a single hydrophone. In order to solve the engineering application problem, a sound-pressure sound-pressure-gradient hydrophone is designed in this paper. The new composite hydrophone consists of two channels. The bionic cilium microstructure is optimized and used as the vector channel, to collect the sound pressure gradient information, and a scalar channel, based on a piezoelectric ceramic tube, is added, to receive the sound pressure information. The theoretical analysis, simulation analysis, and test analysis of the composite hydrophone are carried out, respectively. The test results show that the sensitivities of the hydrophone can reach up to −188 dB (vector channel) and −204 dB (scalar channel). The problem of left–right ambiguity is solved by combining the sound pressure and sound pressure gradient in different ways. This is of great significance in the engineering application of single cilium MEMS hydrophone orientation.

Design and realization of cap-shaped cilia MEMS vector hydrophone

Ciliary MEMS vector hydrophone (CVH) has excellent performance in low-frequency detection, however, there is still the problem of poor sensitivity in some applications. A cap-shaped ciliary vector hydrophone (CCVH) is proposed in this paper. The microstructure not only ensures the working bandwidth of the hydrophone, but also increases the sensitivity. A single integration process is adopted to complete the pasting of the cap-shaped cilia and the cantilever beam, requiring no complicated secondary cilia integration process. Firstly, a mathematical model is established for theoretical derivation, and then the principle is verified via COMSOL simulation. Finally, test results show that the sensitivity of CCVH can reach −182.7 dB at 1 kHz (1 kHz, 0 dB@1 V/µPa). Compared with the CVH, the sensitivity has increased by 14.4 dB. Concave point depth of 8-shaped directivity is beyond 30 dB, which indicates that CCVH has an excellent ability to detect underwater ship noise.

Design and realization of sculpture-shaped ciliary MEMS vector hydrophone

The traditional design of cilium MEMS vector hydrophone (CVH) usually adds attachment to the cilium to increase the force-bearing area of the cilium, which improves the sensitivity of CVH but also greatly reduces the inherent frequency of hydrophone, and brings heavier burden to the cross-beam. Based on the radiation noise of ships that is generally below 1 kHz, this article designs a sculpture-shape cilium MEMS vector hydrophone (SCVH). Compared to traditional CVH, it enhances the sensitivity of hydrophone, increases the resolution of weak signal, and reaches the working frequency band of 1 kHz. In this paper, the stress analysis of cantilever beam is carried out, and then the appropriate size of SCVH is determined by simulation analysis. Finally, the sensitivity and directivity experiments in standing wave tube are carried out. The experimental results show that the sensitivity of SCVH at 1 kHz reaches -184.2 dB (0 dB = 1 V/μPa), 13.1 dB higher than traditional CVH. The working frequency band of SCVH is 20 Hz-1kHZ, and the depth of “8”-shaped directivity concave point is larger than 30 dB.

Design and implementation of a jellyfish otolith-inspired MEMS vector hydrophone for low-frequency detection

Detecting low-frequency underwater acoustic signals can be a challenge for marine applications. Inspired by the notably strong response of the auditory organs of pectis jellyfish to ultralow frequencies, a kind of otolith-inspired vector hydrophone (OVH) is developed, enabled by hollow buoyant spheres atop cilia. Full parametric analysis is performed to optimize the cilium structure in order to balance the resonance frequency and sensitivity. After the structural parameters of the OVH are determined, the stress distributions of various vector hydrophones are simulated and analyzed. The shock resistance of the OVH is also investigated. Finally, the OVH is fabricated and calibrated. The receiving sensitivity of the OVH is measured to be as high as −202.1 dB@100 Hz (0 dB@1 V/μPa), and the average equivalent pressure sensitivity over the frequency range of interest of the OVH reaches −173.8 dB when the frequency ranges from 20 to 200 Hz. The 3 dB polar width of the directivity pattern for the OVH is measured as 87°. Moreover, the OVH is demonstrated to operate under 10 MPa hydrostatic pressure. These results show that the OVH is promising in low-frequency underwater acoustic detection.

Design and development of a broadband spherical hydrophone using PZT-4

Majority of the sensors for underwater application use acoustic waves for detection, communication and navigation of submersibles. Hydrophone, used for sensing acoustic signals in water, has piezoelectric material within which responds to acoustic pressure by generating electric potential. Different types of hydrophones having different shapes can be manufactured depending on their applications. An omni-directional hydrophone can be developed using a spherical piezoelectric material as active material. This paper describes the design and development of a spherical hydrophone using lead zirconate titanate-4 (PZT-4) hollow sphere, having Receiving Sensitivity (RS) − 205 ± 0.6 dB ref 1 V/µPa in the frequency band 0–10 kHz. Analytical modelling of the piezoelectric sphere is done to fix its dimensions for the desired output and numerical analysis is done in COMSOL Multiphysics to validate the result. Since the spherical hydrophone is manufactured by encapsulating the piezoelectric sphere with polymer to give water-tight insulation, numerical analysis of the piezoelectric sphere coated with a polymer is done to calculate the RS of the hydrophone. Fabrication of a spherical hydrophone is done by rubber encapsulation of the piezoelectric sphere using compression moulding technique and its RS is measured in water. RS values obtained from numerical analysis and experiment are having a good agreement in the frequency band 0–10 kHz.

Design and implementation of hollow cilium cylinder MEMS vector hydrophone

The cilium MEMS vector hydrophone (CVH) plays an important role in detecting underwater acoustic targets, but there are still problems of low sensitivity and insufficient working bandwidth. In this paper, hollow cilium cylinder vector hydrophone (HCVH) is presented, which can improve sensitivity and working bandwidth within a certain range. Acting as the received acoustic signal structure, a hollow cylinder can not only ensure that sensitivity is improved by increasing the size of area which receives sound, but also reduce its weight to improve the stability of hydrophone. Through the theoretical analysis and the simulation, the relationship between the structure parameters and working performance of the hydrophone is obtained, and the specific size of the sensitive structure is determined. The experimental results show that the sensitivity of HCVH is increased by 8.7 dB in 20–1000 Hz, reaching up to −185.6 dB (re 1 V/µPa) at 1250 Hz. In addition, HCVH has a good directivity.

Design and fabrication of a novel MEMS piezoelectric hydrophone

Hydrophone, serving as a part of sonar, has a significant effect on the performance of acoustic sensors such as frequency characteristics and sensitivity, however, some limitation such as high cost and complexity in SOI manufacturing technique hinder the industrial application of hydrophones. Therefore, a novel Micro-Electro-Mechanical Systems (MEMS) piezoelectric vector hydrophone based on PZT (lead zirconate titanate) film has been adopted in obtaining vector information of underwater sound field. The piezoelectric hydrophone sensor was analyzed, designed and fabricated with PZT-on-Si substrate, and the structure consists of a four-cantilevers and an acoustics columnar cilium fixed on the center micro mass. According to the simulation results, the piezoelectric films are optimally distributed at the tip of the four beams, where the maximum strain locates. Finally, the piezoelectric vector hydrophone was characterized by comparative calibration experiments in a standing wave bucket. This passive MEMS piezoelectric hydrophone has the characteristics of receiving sensitivity with −189.3 dB at 920 Hz (0dB = 1 V/μPa) and a typical directional pattern of "8" shape, low noise output and high dynamic test range, which is suitable for high precision passive underwater detection.

Design and realization of dumbbell-shaped ciliary MEMS vector hydrophone

An excellent hydrophone should have higher sensitivity in its working frequency-band to provide signal with better quality for direction of arrival (DOA). Aiming at the centralized distribution of radiation noise from ships generally below 1KHz, a Dumbbell-shaped ciliary MEMS vector hydrophone (DCVH) with better sensitivity below 1KHz is designed in this paper. When detecting the submarine sound signal, Dumbbell-shaped ciliary can obtain the area of receiving sound waves larger than common ciliary structure in the same mass, increase the center of gravity position and increase the moment of force, so as to improve the high sensitivity of hydrophone under the premise of meeting the working frequency-band. In addition, the use of resin as the material for making cilia can bring better performance to hydrophone. Through theoretical analysis and simulation verification by COMSOL5.4, the design is feasible. Finally, DCVH is verified by hydrophone test calibration system, with the sensitivity of -186.1dB (1KHz, 0dB=1V/μPa), 10.8dB higher than bionic ciliary MEMS vector hydrophone (CVH), the working frequency-band of 20Hz-1KHz, the excellent “8″ character directivity, and concave point depth exceeding 30dB, which is consistent with theory and simulation results and meets the design requirements.

Design of a MEMS bionic vector hydrophone with piezo-gated MOSFET readout

A new design of a MEMS bionic vector hydrophone based on piezoelectric transduction has been proposed. The designed hydrophone has a higher sensitivity in comparison to its previous counterparts. Readout electronics includes embedded MOSFETs and external operational amplifiers. MOSFETs with piezoelectric gates are integrated to the beams and have been used as the strain to electrical current transducers. The drains of the MOSFETs have been connected to operational amplifiers that convert the transistor currents to the voltage and also amplify the output. The changes in the channel length and mobility are negligible and the transistor current is merely under the influence of the pressure induced charges on the piezoelectric surface which directly produce the vertical electric field. Designed hydrophone characterized with the sensitivity up to −146.2 ​dB (Ref. 1 ​V/μPa) for frequencies up to about 3 ​kHz. The results verify the possibility of utilizing the proposed design as an underwater acoustic sensor with a high sensitivity and a wide frequency range.

Design and implementation of two-component cilia cylinder MEMS vector hydrophone

In previous studies of MEMS vector hydrophone, the ideas of increasing the sound signal reception area were only considered for improving the sensitivity of cilium MEMS vector hydrophone (CVH), which lead to a problem of increasing the load of cantilever beam. In order to solve the problem, a two-component cilia cylinder MEMS vector hydrophone (TCVH) is developed in this paper. TCVH can improve the sensitivity of MEMS vector hydrophone with the same load of cantilever beam as CVH. Firstly, device structure parameters of the two-component cilia cylinder and cross-beam are determined based on the theoretical analysis and simulation analysis. Compared with the modal shapes of CVH, the overall structure of TCVH is more stable. And in terms of fabrication, the secondary integration process become more simple than that of previous works due to the consistency of the upper and lower cilia materials as well as the feature of no mould. Then, the results of the standing waves field comparison calibration test show that compared with CVH, the sensitivity of TCVH is increased by 4.5 dB on the condition of same load on cantilever beam in the range of 20–1000 Hz. In addition, the sensitivity of an optimized dimension structure can be increased by 8.3 dB, reaching up to −188.1 dB (1KHz 0 dB at 1 V/μPa). Finally, the “8” shape directivity and concave point depth (>30 dB) demonstrate that the TCVH has a good target detection capability.

Correction to: Design and modeling of a novel high sensitive MEMS piezoelectric vector hydrophone

In the original article, one of the co-author’s (Morteza Dardel) family name has been published incorrectly. The correct family name should be Dardel. The original article has been corrected.

Design and modeling of a novel high sensitive MEMS piezoelectric vector hydrophone

In this paper, a novel micro electromechanical systems (MEMS) piezoelectric hydrophone with the ability to detect the direction of the sound in two dimensions was designed and analyzed. Piezoelectric hydrophones are widely used today. These devices constitute the main part of the sonar systems. Sonars are used in marine vessels and for transportation of marine military equipment, such as submarines and battleships. Hydrophones work by converting received sound pressure to electrical signals. The idea of the present paper for designing hydrophones is taken from sea creatures and use artificial hair cell structure. This structure not only has the advantages of piezoelectric sensors such as being active and having optimal sensitivity, but it is also able to detect the direction of the sound and work at low frequencies, the performance of the sensor has been improved compared with the previous works (Ito et al. in Sens Actuators, 2008; Choi et al. in Sens Actuators, 2010; Guan et al. in Microsyst Technol, 2011; Sens Actuators, 2012; Zhang et al. in Design of a monolithic integrated three-dimensional MEMS bionic vector hydrophone, 2014), in a way that its sensitivity is ź 191 dB in the frequency range of below 10.4 kHz (0 dB re 1 V/μPa).

Design of the Monolithic Integrated Array MEMS Hydrophone

Since the sensitivity and frequency band of the micro-electro-mechanical system (MEMS) bionic vector hydrophone restrain each other, a single hydrophone can not simultaneously meet the high sensitivity and wide frequency band requirements. Therefore, in this paper, based on a single MEMS bionic vector hydrophone, a $2\times 2$ four-unit array microstructure on a chip has been proposed to realize both high sensitivity and wide frequency band, which consists of four four-beam-cilium structures with different cilium lengths of 10000, 8000, 6000, and 3000 $\mu {\mathrm{ m}}$ , respectively. The array structure sizes are determined by the theoretical and simulation analysis, and then the array structure is fabricated integrally by the MEMS manufacturing technology. Finally, this paper presents the experimental characterization of the packaged array hydrophone in a standing wave tube to validate the theory and the simulation. The test results show that the array hydrophone has high sensitivity and good frequency response, exhibiting the highest sensitivity of −189 dB (without pre-amplifier, 0 dB reference 1 V/uPa) and frequency band of 20–5000 Hz, both bearing witness to a good directivity in the shape of 8. The improvements of the hydrophone performance broaden its application scope.