Prenatal acoustic programming of mitochondrial function for high temperatures in an arid-adapted bird

Sound is an essential source of information in many taxa and can notably be used by embryos to programme their phenotypes for postnatal environments. While underlying mechanisms are mostly unknown, there is growing evidence for the involvement of mitochondria—main source of cellular energy (i.e. ATP)—in developmental programming processes. Here, we tested whether prenatal sound programmes mitochondrial metabolism. In the arid-adapted zebra finch, prenatal exposure to ‘heat-calls’—produced by parents incubating at high temperatures—adaptively alters nestling growth in the heat. We measured red blood cell mitochondrial function, in nestlings exposed prenatally to heat- or control-calls, and reared in contrasting thermal environments. Exposure to high temperatures always reduced mitochondrial ATP production efficiency. However, as expected to reduce heat production, prenatal exposure to heat-calls improved mitochondrial efficiency under mild heat conditions. In addition, when exposed to an acute heat-challenge, LEAK respiration was higher in heat-call nestlings, and mitochondrial efficiency low across temperatures. Consistent with its role in reducing oxidative damage, LEAK under extreme heat was also higher in fast growing nestlings. Our study therefore provides the first demonstration of mitochondrial acoustic sensitivity, and brings us closer to understanding the underpinning of acoustic developmental programming and avian strategies for heat adaptation.

Fabrication and calibration of nanostructured Vanadium-doped ZnO-based micromachined sensor with superior sensitive for underwater acoustic measurement

A high-performance micromachined piezoelectric sensor based nanostructured Vanadium-doped Zinc oxide (ZnO) film with air-backing has been developed and characterized for underwater acoustic application. The sensing cell with a low foot-print of 2.0 mm × 2.0 mm is fabricated by MEMS technology using a ZnO-on-SOI process platform. An optimal ratio of piezoelectric coefficient to the relative permittivity is obtained about 6.3 in the Zn0.98V0.02O sensing cell, improving by an order of magnitude compared with other notable piezoelectric films, plays a mainly dominant role in the enhanced piezoelectric response. Calibrations in the standard underwater instrument have demonstrated that the presented sensor could achieve an acoustic pressure sensitivity of −165 ± 2 dB (Ref. 1 V/μPa) over a bandwidth 10 Hz to 10 kHz, outperforming the same kind of reported devices. The maximum non-linearity is no more than 0.3% and the sensitivity variation is no more than ± 0.7 dB in the temperature range from 10℃ to 50 ℃ indicating a better stability and higher reliability. The proposed sensor with a superior acoustic sensitivity gives a great application potential in underwater acoustic measurements.

Coupled D33 Mode-Based High Performing Bio-Inspired Piezoelectric MEMS Directional Microphone

Microelectromechanical system (MEMS) directional microphones have been identified as having use in multi-projected virtual reality applications such as virtual meetings for projecting cameras. In these applications, the acoustic sensitivity plays a vital role as it biases the directional sensing, signal-to-noise ratio (SNR) and self-noise. The acoustic sensitivity is the multiplied outcome of the mechanical sensitivity and the electrical sensitivity. As the dimensions are limited in MEMS technology, the improvement of the acoustic sensitivity by reflecting the mechanical as well as electrical domains is a challenge. This paper reports on a new formation of the D33 mode, the coupled D33 mode, based on piezoelectric sensing to improve the acoustic functionalities. The unique advancement of the proposed D33 mode is that it allows multiple spans of the regular D33 mode to perform together, despite this increasing the diaphragm’s dimensions. At a reduced diaphragm size, the orientation of the coupled D33 mode realizes the maximum conversion of the mechanical deflection into electrical sensitivity. The significance of the proposed D33 mode in comparison to the regular D33 mode is simulated using COMSOL Multiphysics. Then, for a proof–of–concept, the experimental validation is carried out using a piezoelectric MEMS directional microphone inspired by the ears of the fly Ormia ochracea. In both ways, the results are found to be substantially improved in comparison with the regular approach of the D33 mode, showing the novelty of this work.

An all-Optical Photoacoustic Sensor for the Detection of Trace Gas

A highly sensitive Fabry–Perot based transduction method is proposed as an all-optical alternative for the detection of trace gas by the photoacoustic spectroscopy technique. A lumped element model is firstly devised to help design the whole system and is successfully compared to finite element method simulations. The fabricated Fabry–Perot microphone consists in a hinged cantilever based diaphragm, processed by laser cutting, and directly assembled at the tip of an optical fiber. We find a high acoustic sensitivity of 630 mV/Pa and a state-of-the-art noise equivalent pressure, as low as ~ 2 μ Pa / Hz at resonance. For photoacoustic trace gas detection, the Fabry–Perot microphone is further embedded in a cylindrical multipass cell and shows an ultimate detection limit of 15 ppb of NO in nitrogen. The proposed optical trace gas sensor offers the advantages of high sensitivity and easy assembling, as well as the possibility of remote detection.

Acoustic Measurement of Ultrasound Sensors in a Water Bath

PMN-PT is one of promising materials for fabrication ultrasound sensors for flow metering, in that the relative permittivity and the dielectric loss factor are superior to PZT, the popular piezoelectric materials at present. However, there are not many studies focusing on characterizing the PMN-PT ultrasound sensors by acoustic measurements. This study introduces an acoustic bath to accommodate a pair of ultrasound sensors for measuring the relative acoustic sensitivity and the dispersion angle by ultrasound waves. Ultrasound sensors with resonance frequencies from 0.2 MHz to 1 MHz are also tested in terms of the relative permittivity, the dielectric loss factor, the electric impedance, and the electric admittance. From these measurements, it is found that PMN-PT is superior to PZT for increasing the relative acoustic sensitivity of ultrasound sensors. Impedance matching electronic circuits are fabricated by designing capacitance and inductance with the reflectance coefficients. Smith chart is used to calculate the capacitance and the inductance for the PMN-PT ultrasound sensors with resonance frequencies of 0.2 MHz and 0.5 MHz. As a results, it is also found that the impedance matching electronic circuits enhance the electrical admittance by 3.6 ∼ 25 times while keeping the electrical impedance between 50 Ω and 100 Ω.

Design of a New Type of Optical Fiber Infrasound Sensor and Its Usage in Karst Geological Exploration

In this study, the demand of optical fiber (OF) sonic sensor is analyzed, and a composite OF infrasound sensor is proposed aiming at the detection demand of low-frequency infrasound waves in specific occasions. With this sensor, the polymer thin film and the aluminum soil can be combined to form a kind of composite film, the ECF/P interferometer can be formed between the end faces of the ferrule of the OF FC contact, the sensor head of the OF ECF/P infrasound sensor system is fabricated and then packaged. The designed OF infrasound sensor is used in the construction of a wireless sensor network (WSN) for karst geological exploration. The structure of the WSN includes the SimpliciTI communication network protocol, ADF7021 RF transceiver chip, STM32 processor chip, etc. New types of environment from karst can be sampled with this WSN. During the test, the performance of the composite OF infrasound sensor is analyzed at the beginning. The acoustic sensitivity of up to –136.73 dB re 1 V/μPa can be obtained in the low frequency infrasound range (1–20 Hz); the WSN based on the composite OF infrasound sensor has lower power consumption and faster networking speed. In addition, it can realize signal cover in karst areas without public mobile cellular networks, and send the information collected by the sensor to the data center, thus proving the fiber optic sound wave sensor designed in this study is successful and helpful for the geological prospectors to monitor the environment.

Side-Polished Fiber-Optic Line Sensor for High-Frequency Broadband Ultrasound Detection

We demonstrate a side-polished fiber-optic ultrasound sensor (SPFS) with a broad frequency bandwidth (dc–46 MHz at 6-dB reduction) and a wide amplitude detection range from several kPa to 4.8 MPa. It also exhibits a high acoustic sensitivity of 426 mV/MPa with a signal-to-noise ratio of 35 dB and a noise-equivalent pressure of 6.6 kPa (over 1–50 MHz bandwidth) measured at 7-MHz frequency. The SPFS does not require multi-layer-coated structures that are used in other high-sensitivity optical detectors. Without any coating, this uses a microscale-roughened structure for evanescent-field interaction with an external medium acoustically modulated. Such unique structure allows significantly high sensitivity despite having a small detection area of only 0.016 mm2 as a narrow line sensor with a width of 8 μm. The SPFS performance is characterized in terms of acoustic frequency, amplitude responses, and sensitivities that are compared with those of a 1-mm diameter piezoelectric hydrophone used as a reference.