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This paper delves into enhancing the performance of ScAlN-based Piezoelectric Micromachined Ultrasonic Transducers (PMUTs) through the implementation of Polydimethylsiloxane (PDMS) acoustic lenses. The PMUT, encapsulated in PDMS, underwent thorough characterization through the utilization of an industry-standard hydrophone calibration instrument. The experimental results showed that the ScAlN-based PMUT with the PDMS lenses achieved an impressive sensitivity of −160 dB (re: 1 V/μPa), an improvement of more than 8 dB compared to the PMUT with an equivalent PDMS film. There was a noticeable improvement in the −3 dB main lobe width within the frequency response when comparing the PMUT with PDMS encapsulation, both with and without lenses. The successful fabrication of high-performance PDMS lenses proved instrumental in significantly boosting the sensitivity of the PMUT. Comprehensive performance evaluations underscored that the designed PMUT in this investigation surpassed its counterparts reported in the literature and commercially available transducers. This encouraging outcome emphasizes its substantial potential for commercial applications. [ABSTRACT FROM AUTHOR]

Inspired from fish bionics, an anulus-shaped ciliary structure for four-unit MEMS vector hydrophone (AFUVH) is proposed in this paper. It replaces the previous bionic cilium-shaped structure and becomes a novel sensing structure in the four-unit MEMS vector hydrophone (FUVH), which realizes the complete simulation of the fish lateral line neuromasts structurally and functionally. It not only improves the sensitivity of FUVH, but also retains a sufficient bandwidth, which improves the overall performance of FUVH for monitoring remote ships noise. Meanwhile, this paper theoretically analyzes the performance of AFUVH for detecting acoustic signals. ANSYS 17.0 simulation is used to derive the parameters of effective structure and optimum dimension structure of annulus-shaped ciliary structure. Finally, the experimental results show that comparing with cilium-structured FUVH, the sensitivity of AFUVH with effective structure is increased by 3.92 dB, and the sensitivity of AFUVH with optimum dimension structure is increased by 5.87 dB, reaching up to −177.53 dB.

With advances in new materials and technologies, there has been increasing research focused on flexible sensors. However, in most flexible pressure sensors made using new materials, it is challenging to achieve high detection sensitivity across a wide pressure range. Although traditional silicon-based sensors have good performance, they are not formable and, because of their rigidity and brittleness, they are not suitable for fitting with soft human skin, which limits their application in wearable devices to collect various signals. Silicon nanomembranes are ultra-thin, flexible materials with excellent piezoresistive properties, and they can be applied in various fields, such as in soft robots and flexible devices. In this study, we developed a flexible pressure sensor based on the use of silicon nanomembranes (with a thickness of only 340 nm) as piezoresistive units, which were transferred onto a flexible polydimethylsiloxane (PDMS) substrate. The flexible pressure sensor operated normally in the range of 0–200 kPa, and the sensitivity of the sensor reached 0.0185 kPa−1 in the low-pressure range of 0–5 kPa. In the high-pressure range of 5–200 kPa, the sensitivity of the sensor was maintained at 0.0023 kPa−1. The proposed sensor exhibited a fast response and excellent long-term stability and could recognize human movements, such as the bending of fingers and wrist joints, while maintaining a stable output. Thus, the developed flexible pressure sensor has promising applications in body monitoring and wearable devices. [ABSTRACT FROM AUTHOR]

Aiming at the low sensitivity of traditional stethoscope and the application value of electronic stethoscope in the early diagnosis of cardiovascular diseases, in this paper,a bionic electronic stethoscopes based on MEMS technology is designed. The feasibility of micro-structure of MEMS electronic sensor is verified by theoretical analysis and finite element simulation. And the sensor acquisition circuit and the PC upper machine are designed for the real-time acquisition of heart sound signal. The focuses of this paper is to design and optimize the micro-structure of the sensor, and improve of the working bandwidth and the signal-to-noise ratio. The final test results show that the sensitivity of the sensor is −189.5dB (@500Hz), the working bandwidth is 20-600Hz, and the SNR is 25.62dB, which is 2.59dB higher than the similar products of 3M Littmann 3200 electronic stethoscope. [ABSTRACT FROM AUTHOR]

At present, more and more flexible pressure sensors are used in wearable devices. The improvement of the adsorbability of nanomaterials on sponge flexible pressure sensors is an urgent problem to be solved. Here, using conductive carbon black with good dispersibility and small particle size as the conductive filler filled in the middle of the sponge can improve the absorbability of the sponge. A simple method of soaking a sponge with different thicknesses in conductive carbon black dispersion is used to obtain flexible pressure sensors based on conductive carbon black/sponge. We compare and analyze the differences in initial resistance and sensitivity of sponge pressure sensors with different thicknesses and select the sensor with higher sensitivity (0.194 kPa−1) for response time, recovery time, and stability tests. The sensor is used in the neck, wrist, knee, and other body parts for motion recognition. The two conductive carbon black/sponge sensors are placed orthogonally on the back to identify nod, tilt head, and placed on the elbow to test the angle of arm bending. Conductive carbon black/sponge flexible pressure sensor shows good application prospects in the wearable field. [ABSTRACT FROM AUTHOR]

During underwater acoustic detection, the positioning accuracy of the bionic cilia MEMS vector hydrophone is affected by its own sensitivity. MEMS vector hydrophone operate in different temperature environments, so studies on the environmental temperature and the sensitivity of the MEMS vector hydrophone are of great significance. In this paper, based on the sensitivity of the MEMS vector hydrophone at room temperature (22°C), its sensitivity variation is studied within the temperature range of 0–40°C. The relationship between the temperature and the piezoresistor in the MEMS vector hydrophone is theoretically analyzed, and it is concluded that the sensitivity change is within ±0.6dB. The sensitivity change of MEMS vector hydrophone is proved to be within ±0.3 dB via COMSOL 5.4 simulation software, and the MEMS vector hydrophone is verified experimentally by the hydrophone temperature characteristic testing system. The results show that the variation of the sensitivity is within ±0.5 dB, which is basically consistent with the theoretical analysis results and simulation results. It can be said that under normal non-extreme ambient temperature, the operating temperature has little effect on the sensitivity of the MEMS vector hydrophone. [ABSTRACT FROM AUTHOR]

Inspired from fish bionics, an anulus-shaped ciliary structure for four-unit MEMS vector hydrophone (AFUVH) is proposed in this paper. It replaces the previous bionic cilium-shaped structure and becomes a novel sensing structure in the four-unit MEMS vector hydrophone (FUVH), which realizes the complete simulation of the fish lateral line neuromasts structurally and functionally. It not only improves the sensitivity of FUVH, but also retains a sufficient bandwidth, which improves the overall performance of FUVH for monitoring remote ships noise. Meanwhile, this paper theoretically analyzes the performance of AFUVH for detecting acoustic signals. ANSYS 17.0 simulation is used to derive the parameters of effective structure and optimum dimension structure of annulus-shaped ciliary structure. Finally, the experimental results show that comparing with cilium-structured FUVH, the sensitivity of AFUVH with effective structure is increased by 3.92 dB, and the sensitivity of AFUVH with optimum dimension structure is increased by 5.87 dB, reaching up to −177.53 dB. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to present a novel nitrile butadiene rubber (NBR) packaging structure, which can solve the problems of the low sensitivity, narrow frequency band and fluctuating frequency response curve of the MEMS bionic vector hydrophone. Design/methodology/approach – A 0.05-mm-thick NBR sound-transparent cap was designed by theoretical analysis and simulation to reduce the signal attenuation caused by the packaging structure, and the frequency band of the hydrophone has been extended to 4 kHz. In this work, the vector hydrophone was fabricated by the MEMS technology and packaged with the NBR sound-transparent cap. The performance indicators were calibrated in the National Defence Underwater Acoustics Calibration Laboratory of China. Findings – The results show that the sensitivity of NBR-packaged hydrophone reaches −170 dB (±2 dB), and the difference is less than 1 dB compared to bare chip. And the frequency band is 50 Hz-4 kHz. The hydrophone also has good directional pattern in the form of an 8-shape, and the pressure-resisting ability is more than 2 MPa. Originality/value – The packaging structure significantly increases the sensitivity of the hydrophone and broadens the frequency band, providing a new method in the packaging design for MEMS hydrophone. [ABSTRACT FROM AUTHOR]

We optimize the package of the cilium-type MEMS bionic vector hydrophone introduced by Chenyang and Wendong in 2007, which has the disadvantages of a low receiving sensitivity, narrow frequency band, and fluctuating frequency response curve. Initially, a full parametric analysis of frequency response and sensitivity with different material sound transparent cap were made. Then, we propose and realize an umbrella-type packaged structure with high receiving sensitivity and wide frequency band. The theoretical analysis and simulation analysis are conducted by ANSYS software and LMS virtual. Lab acoustic software. Finally, to verify the practicability of the package, the umbrella-type packaged hydrophone calibration was carried out in the National Defense Underwater Acoustics Calibration Laboratory of China. The test results show that the performance of umbrella-type hydrophone has been greatly improved compared with the previous packaged hydrophone: exhibiting a receiving sensitivity of -178 dB (increasing by 20 dB, 0-dB reference 1 V/μPa), the frequency response ranging from 20 Hz to 2 kHz (broaden one times), the fluctuation of frequency response curve within ±2 dB, and a good dipole directivity. [ABSTRACT FROM PUBLISHER]

The paper reports a GaAs micro accelerometer by making use of the electromechanical coupling effect based on metal-semiconductor field effect transistor (MESFET). MESFET as a sensitive unit is located at high-stress region to detect the nanometers deformation under stress. The electromechanical coupling effect is validated, and at the same time, the piezoresistive effect and sensitivity, including linear, transition and saturation regions are analyzed under different voltage bias using static and dynamic testing methods. The results indicate that the piezoresistive coefficient and sensitivity of microstructure strongly depend on voltage bias. The transition region between the saturated and linear regions shows a greater sensitivity and piezoresistive coefficient. As a result, the GaAs microstructure based on MESFET can obtain higher piezoresistive coefficient and sensitivity by optimizing the combination of gate and drain voltage. [ABSTRACT FROM PUBLISHER]

• The sensitivity of the hydrophone under hydrostatic pressure is simulated. • A simple test method of hydrophone under hydrostatic pressure is proposed. • The sensitivity of the MEMS vector hydrophone under hydrostatic pressure is studied. • Reduce the influence of uncertainty in the application of MEMS vector hydrophone. Hydrophones are one of the main sensors for underwater acoustic signal detection, and their positioning accuracy is closely related to their sensitivity. However, in practice, hydrophones need to work in different depths of water environment. The ciliated MEMS vector hydrophone has a four-beam structure and has a certain anti-interference ability against hydrostatic pressure. However, due to the manufacturing process and other reasons, there may be certain errors in the production of varistors, which leads to the hydrophone's resistance to hydrostatic pressure. The resistance to the impact is reduced. Therefore, studying the influence of hydrostatic pressure environment on the sensitivity of MEMS vector hydrophones is of great significance to the application of MEMS vector hydrophones. According to the application environment of MEMS vector hydrophone, the sensitivity of MEMS vector hydrophone is studied in this paper within the range of hydrostatic pressure 1 atm ∼ 12 MPa. In this paper, the influence of hydrostatic pressure on the sound transmission loss and piezoresistor are studied to theoretically verify that the hydrostatic pressure has little effect on the sensitivity of MEMS vector hydrophone. It is verified by COMSOL5.6 software simulation that the sensitivity changes within the pressure range of 1 dB. In order to facilitate the experiment of the MEMS vector hydrophone in the hydrostatic environment, this paper proposed a method of combining an external sound source with a marine environment simulation test machine. It is concluded that within the test pressure range, the sensitivity change of the MEMS vector hydrophone fluctuates within ±1 dB. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

As the core equipment of Underwater acoustic detection, MEMS vector hydrophones are applied to Unmanned Underwater Vehicles (UUV), which can better detect underwater targets. Most of the MEMS vector hydrophones currently used are long-tube cylindrical, relatively large in volume and weight, which is not suitable for installation on UUV. The co-vibration vector hydrophone is small in size and weight, but it needs elastic suspension due to the requirements of the working principle. Therefore, according to the needs of practical engineering applications, this paper designs an Embedded UUV Conformal MEMS Vector Hydrophone (ECVH), establishes an encapsulation model through theoretical analysis, and uses COMSOL6.0 to simulate its acoustic performance. The sensitivity and directionality of the ECVH are verified in the standing wave barrel. When the test frequency is 630 Hz, the sensitivity of the vector channel is −182.3 dB, and the depth of the ' 8 ' direction concave point is greater than 35 dB. The sensitivity of the sound pressure channel is −182 dB, which is omnidirectional. Finally, it is mounted on UUV for preliminary signal acquisition verification test. The test results show that the ECVH can work normally on UUV, which provides a new idea for underwater small platform test. [Display omitted] • An embedded MEMS vector hydrophone conformal with UUV is designed according to the needs of practical application engineering. • The embedded MEMS vector hydrophone is small in size, light in weight and can be rigidly fixed. • The embedded MEMS vector hydrophone has good directivity, and the vector channel is consistent with the sound pressure channel. [ABSTRACT FROM AUTHOR]

Under the premise of ensuring that the working frequency-band reaches 1KHz, the Dumbbell-shaped ciliary structure can improved the sensitivity of the MEMS vector hydrophone. • The Dumbbell-shaped ciliary can obtain the area of receiving sound waves larger than common ciliary structure in the same mass. • The Dumbbell-shaped ciliary can increase the center of gravity position and increase the moment of force than Two-layered cilia. • The Dumbbell-shaped ciliary structure is made by integrated production, which is easier to guarantee the conformity. • The use of resin as the material for making cilia can bring better performance to hydrophone. • Under the premise of ensuring that the working frequency-band reaches 1KHz, the sensitivity of the MEMS vector hydrophone is improved. 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 1 K H z , a Dumbbell-shaped ciliary MEMS vector hydrophone (DCVH) with better sensitivity below 1 K H z 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 - 186.1 d B (1 K H z , 0 d B = 1 V / μ P a), 10.8 d B higher than bionic ciliary MEMS vector hydrophone (CVH), the working frequency-band of 20 H z - 1 K H z , the excellent "8″ character directivity, and concave point depth exceeding 30 d B , which is consistent with theory and simulation results and meets the design requirements. [ABSTRACT FROM AUTHOR]

• A novel MEMS vector hydrophone was designed for applying based on piezoresistive effect and fish bionics in the range of 20 Hz–1628 Hz. • Compared with previous studies, fabrication of this micro-structure can be made more simple and efficient. • By using Design Exploration function of ANSYS19.0 software, the optimum solution of the highest sensitivity was obtained with the restrictions of bandwidth. • The MEMS vector hydrophone have a good performance for engineering application, such as the high sensitivity and 8-shape directivity, the wider working bandwidth could realizes the dual use of military and civilian. The previous cilia MEMS vector hydrophone were mainly aimed at monitoring the noises of remote ships due to the limitation of frequency band. Moreover, the methods of adding appendants to cilia were usually used to improve the sensitivity, which increased the difficulty of fabrication, secondary integration and the consistency of production. In this paper, based on the bionic principle of multiple cilia on fishes' sense cells, a cilia cluster MEMS vector hydrophone(CCVH) is designed. This micro-structure not only improves the sensitivity of hydrophone without adding appendants to cilia, but also designs a suitable frequency band to monitor ships and some valuable marine species. Firstly, a mathematical model is established for theoretical analysis. Then, simulation analysis is carried out to verify the correctness of theoretical analysis, and the optimal size of cilia is found simultaneously. Secondly, the fabrication of cilia cluster MEMS vector hydrophone is more simpler because the cilia have the same properties and integrated process. Finally, test results show that the sensitivity of hydrophone has been increased by 9.6 dB, which can reach up to -183.3 dB@1600 Hz(0 dB ref.1 V/uPa) with the frequency band in the range of 20 Hz-1 kHz. Besides, the sensitivity is increased by 6 dB per octave. Concave point depth of 8-shaped directivity is beyond 30 dB, which indicates that CCVH is promising in underwater application. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

We demonstrate a surface-enhanced Raman scattering (SERS) sensor based on carboxyl-functionalized core-shell structure of Ag@SiO 2 nanoparticles (NPs) active substrate. For selective molecular capturing, the active substrate was functionalized by carboxyl terminal groups to form a negatively charged surface. Experimental results indicate that the SERS sensitivity of the NPs was improved significantly for detecting the positively charged substances. The experimental results provide a potential method for preparing highly sensitive biochemical sensors, especially in the application of recognizing specific molecules accurately. [ABSTRACT FROM AUTHOR]

• MEMS Co-vibration Combined Hydrophone has excellent cosine pointing and high sensitivity. The precise positioning of weak signals can be achieved. • MEMS microphones are used as scalar channels to avoid the problem of ambiguity of sound positioning on the port and starboard of MEMS Co-vibration Combined Hydrophone. • MEMS Co-vibration Combined Hydrophone has the advantages of low power consumption and low cost. • The microphone is used as a scalar channel to reduce the volume of the MEMS Co-vibration Combined Hydrophone and enhance the concealment of the UUV operation. This paper proposes a MEMS co-vibration combined hydrophone (CCH) to position the weak acoustic source of small-volume UUV acoustic self-guided cabins. With an external diameter of 36 mm, it adopts the MEMS triaxial accelerometer to form the vector channel and the MEMS capacitive omnidirectional microphone to form the scalar channel. This paper first analyzes the acoustic receiving model of an elastic-free sphere in water, designs a MEMS co-vibration combined hydrophone packaging and then simulates its acoustic performance. The average density of the encapsulated CCH is 1.01 g/cm3. The vector channel bandwidth is 20 Hz−1,000 Hz, and the sensitivity is −173 dB @ 1 kHz (re 1 V/ μPa) with good cosine directivity. The scalar channel sensitivity is −171 dB @ 1 kHz (re 1 V/ μPa) with omnidirectional directivity. The error of the orientation test in the standing wave tube is less than 1 degree. The sound source-level test results are mostly consistent with the theoretical calculation based on the actual distance. The above results indicate that the hydrophone can be mounted to UUV to perform sound source detection, which can meet the need for precise positioning, and has a specific application value. [ABSTRACT FROM AUTHOR]

• Design of a novel cilia MEMS vector hydrophone based on piezoresistive effect and bionic principle. • The Crossed-circle structure enlarges the acoustic receiving area. • The Crossed-circle structure is simple to manufacture. • Crossed-circle MEMS ciliary vector hydrophone improves the sensitivity and broadens the working bandwidth. 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 （0 dB = 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. [ABSTRACT FROM AUTHOR]

• Design of a novel MEMS vector hydrophone based on fish bionics. • A new packaging structure is proposed. • The feasibility of the hydrophone is proved with theory and experiment. • The hydrophone has the high sensitivity and wide working bandwidth. The polyurethane-encapsulated lateral line-inspired MEMS vector hydrophone has problems such as low-frequency sensitivity (10–80 Hz) loss and narrow working bandwidth. In order to eliminate these two problems, a new encapsulation with a stainless steel mesh cap structure was proposed. This paper first verified the sensitivity loss and narrow working bandwidth of the polyurethane encapsulation through experiments and simulations, analyzed the impact of the perforation rate, thickness, and aperture of the stainless steel mesh cap structure on the vector hydrophone through simulation, and finally made 8 types of stainless steel mesh cap with different apertures was tested experimentally. Finally, the experimental results show that the sensitivity of the stainless steel mesh encapsulation in the low frequency range (10–80 Hz) is improved by an average of 12 dB than that of the polyurethane encapsulation, and the working bandwidth has been increased from 10–210 Hz to 10–667 Hz. [ABSTRACT FROM AUTHOR]

• Compared with the PNS standard sensor, the cilia sensor can perform two-dimensional turbulence observation. • Streamlined package design can enhance the effect of flow diversion. • The sensitivity of the lollipop-shaped cilia sensor is almost 50 times more than that of the PNS sensor. [Display omitted] A lollipop-shaped cilia sensor based on the MEMS vector hydrophone was designed for measuring ocean turbulence. The micro-cross beam structure met successfully detected the ocean turbulence vector. In addition, the cilia were designed in a lollipop shape, which not only increased the turbulence signal receiving area but also achieved better diversion effects. In general, the turbulence signal is usually concentrated in the range 0–200 Hz. The sensor structure was simulated and analyzed and its size was optimized. The frequency response bandwidth was also ensured, leading to improved sensitivity. The results of sensor calibration experiments prove that the lollipop-type cilia sensor has high sensitivity, reaching 2.73×10−2 Vms2/kg. In addition, the vector test results verify that the MEMS turbulence sensor accurately measured the two-dimensional ocean turbulence. [ABSTRACT FROM AUTHOR]

Under the premise of ensuring that the working frequency-band reaches 1KHz, the sculpture-shape ciliary structure can improved the sensitivity of the MEMS vector hydrophone. [Display omitted] • The sculpture-shaped ciliary can obtain the area of receiving sound waves larger than common ciliary structure in the same mass. • The sculpture-shaped ciliary structure is made by integrated production, which is easier to guarantee the conformity. • The use of red wax as the material for making cilia can bring better performance to hydrophone. • Under the premise of ensuring that the working frequency-band reaches 1KHz, the sensitivity of the MEMS vector hydrophone is improved. 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. [ABSTRACT FROM AUTHOR]

• Design of a novel cap-shaped cilia MEMS vector hydrophone. • The cap-like cilia microstructure has a simple fabrication. • The feasibility of the hydrophone is proved with simulation and experiment. • The hydrophone has sufficient bandwidth and the high sensitivity. 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. [ABSTRACT FROM AUTHOR]

• Design of a novel cilia MEMS vector hydrophone based on bionic principle. • The beaded cilia structure is simple to manufacture. • The MEMS vector hydrophone has wide working bandwidth and the higher sensitivity. In view of the problem that the increased difficulty of underwater moving targets detection caused by the development of acoustic stealth technology, a beaded cilia MEMS vector hydrophone (BCVH) is proposed in this paper. Compared with previous cilia structures, it can enlarge the receiving area of acoustic wave to improve sensitivity without the introduction of additional structures. Meanwhile, the introduction of additional mass and the loss of working frequency band are reduced, and the structure is manufactured at one time. In this paper, the design scheme and optimal size of BCVH are determined via theoretical analysis and simulation, then vector hydrophone calibration system is used to verify it. The experimental results show that the sensitivity of BCVH reaches −183.3 dB (@1kHz, 0 d B = 1 V / μ P a), 13.7 dB higher than bionic cilia MEMS vector hydrophone (CVH). Moreover, the depth of concave point of BCVH is more than 30 dB, which has a good directivity. [ABSTRACT FROM AUTHOR]

• Design of a novel MEMS vector hydrophone based on fish bionics. • The hollow cilium cylinder vector hydrophone has a simple fabrication. • The feasibility of the hydrophone is proved with theory and experiment. • The hydrophone has the high sensitivity and wide working bandwidth. 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. [ABSTRACT FROM AUTHOR]