Ultrasound Sensor Research Articles

Etched Silicon-on-Insulator Microring Resonator for Ultrasound Measurement

A novel integrated optical ultrasound sensor based on silicon-on-insulator (SOI) platform is proposed, theoretically analyzed and experimentally demonstrated. By using a selectively etched SOI microring resonator in an add-drop structure, the technique provides a linear and distortion-free sensing response to the ultrasound signal as it prevents the coupling region deformation and removes variations from the power fluctuation of the optical source. The proof-of-concept experimental demonstration of the proposed sensor shows the detection of air-coupled ultrasound pressure at different frequencies and magnitudes, a frequency sensing resolution of 30 Hz and a wide acceptance angle around 75 degrees.

Chalcogenide microfiber-assisted silica microfiber for ultrasound detection.

An ultra-compact ultrasound sensor with a chalcogenide (ChG) microfiber and a silica microfiber is fabricated. It can detect the ultrasound wave generated by a piezoelectric transducer peaked at 3.7MHz. The sensor shows the broadband ultrasound frequency response with a high signal-to-noise ratio (SNR), owing to the high refractive index and small Young's modulus of ChG material. A ChG (${{\rm As}_2}{{\rm Se}_3}$As2Se3) microfiber of 2µm diameter is adhered to the surface of a silica microfiber with a diameter of 5µm via Van der Waals force; the transmission spectrum has high contrast due to multi-mode interference in this hybrid structure. The SNR response could be up to 70dB, especially at low frequency due to the soft ChG microfiber as a sensing unit to magnify the ultrasound signal, along with an SNR over 12dB at ultrasound of 31.2MHz. As a comparison, a silica taper with the same size as the ChG microfiber is also placed on the silica microfiber with a diameter of 5µm to detect an ultrasound signal from 18kHz to 9.4MHz with an SNR lower than that based on the ChG microfiber up to 38.8dB, showing the high sensitivity of the ChG microfiber.

Incubator Analyzer Using Bluetooth Android Display (Humidity & Air Flow)

Abstract— Incubator Analyzer is a calibrator used to calibrate incubator temperature, mattress temperature, noise, humidity and airflow so that conditions in the baby incubator environment remain stable and within normal limits. The purpose of this study is to develop a system for sending data to android and data storage. "Incubator Analyzer Using Bluetooth Appear Android" has four parameters for measuring temperature, noise, humidity, and water flow. Using the Atmega328 microcontroller as a data processor, and the output results will be displayed on the LCD display and equipped with data transmission via bluetooth HC-05 displayed to Android with data storage. The moisture parameter detects humidity quite well where the biggest error is obtained at 1.28% DHT-22, the Ultrasound Sensor HC SR-04 can detect Air Flow with an error of 311.66% as measured by a comparison device. Incubator Design This analyzer is made portable to calibrate baby incubator tools.

Detection of Circular-Crested Lamb Waves Using Surface-Bonded Fiber-Optic Ultrasound Sensors: A Theoretical Perspective

A theoretical framework is established to study the interaction between circular-crested Lamb waves (CCLWs) and a fiber-optic ultrasound sensor (FOUS) bonded onto the surface of a plate structure. CCLW is a universal expression of guided Lamb waves, regardless of the source-sensor distance. In the theory developed here, strain transfer and transformation, birefringence of the fiber sensor, and modulation of refractive index by elasto-optic effects are incorporated. Explicit expression for calculating the ultrasound-induced wavelength shift of fiber Bragg gratings (FBGs) is derived. To showcase application of the established theory in a more general situation, a chirped FBG Fabry-Perot interferometer based FOUS is simulated, in combination with transfer matrix method. Results uncover quantitatively the interplay of the following factors governing the sensor response: 1) co-existence of both axial and lateral normal strains in the fiber, especially in the near field; 2) elasto-optic properties of the fiber material; 3) initial polarization state of the fiber sensor; 4) incident angle of the CCLWs; and 5) ratio between the equivalent ultrasonic wavelength and the effective sensor length. The calculated results uncover the underlying mechanisms responsible for several experimental observations reported but inadequately explained in the literature. The theoretical framework is also applicable to other non-FBG-based FOUSs that rely on phase modulation by ultrasounds.

Modeling of Errors Due to Uncertainties in Ultrasound Sensor Locations in Photoacoustic Tomography.

Photoacoustic tomography is an imaging modality based on the photoacoustic effect caused by the absorption of an externally introduced light pulse. In the inverse problem of photoacoustic tomography, the initial pressure generated through the photoacoustic effect is estimated from a measured photoacoustic time-series utilizing a forward model for ultrasound propagation. Due to the ill-posedness of the inverse problem, errors in the forward model or measurements can result in significant errors in the solution of the inverse problem. In this work, we study modeling of errors caused by uncertainties in ultrasound sensor locations in photoacoustic tomography using a Bayesian framework. The approach is evaluated with simulated and experimental data. The results indicate that the inverse problem of photoacoustic tomography is sensitive even to small uncertainties in sensor locations. Furthermore, these uncertainties can lead to significant errors in the estimates and reduction of the quality of the photoacoustic images. In this work, we show that the errors due to uncertainties in ultrasound sensor locations can be modeled and compensated using Bayesian approximation error modeling.

Short-Range Radar Implemented with Ultrasound Sensor and PSoC5LP

Short-Range Radar Implemented with Ultrasound Sensor and PSoC5LP

Subsea Crude Oil Spill Detection Using Robotic Systems

Underwater Robotic Oil Spill Surveillance (UROSS) system provides constant and autonomous spill surveillance for subsea pipelines. M900 embedded Radio Frequency Identification tags and readers are used to identify pipeline section for surveillance. GY-521 gyrometer and XL-MaxSonar-WR1 ultrasound sensor are used for autonomous navigation. Spills are detected using a METS methane sensor. After spill detection, images of spill site are captured with a L3C-400 Micro Ultras-Miniature Color Camera and spill location is obtained using GPS. Spill Images and location are transmitted to a remote PC on the nearest off shore platform using an Xbee Pro 900HP wireless connection. An Ocean Signal rescueME Personal Beacon Locator transmits a 406 MHz distress signal via satellite to emergency services communicating the identification of a spill. Power analysis showed the system’s ability to remain submerged and to provide surveillance for 100 m sections of a subsea pipeline once every 24 hrs for a month, and can be increased to every hour for 51 months.

Subsea Crude Oil Spill Detection Using Robotic Systems

Underwater Robotic Oil Spill Surveillance (UROSS) system provides constant and autonomous spill surveillance for subsea pipelines. M900 embedded Radio Frequency Identification tags and readers are used to identify pipeline section for surveillance. GY-521 gyrometer and XL-MaxSonar-WR1 ultrasound sensor are used for autonomous navigation. Spills are detected using a METS methane sensor. After spill detection, images of spill site are captured with a L3C-400 Micro Ultras-Miniature Color Camera and spill location is obtained using GPS. Spill Images and location are transmitted to a remote PC on the nearest off shore platform using an Xbee Pro 900HP wireless connection. An Ocean Signal rescueME Personal Beacon Locator transmits a 406 MHz distress signal via satellite to emergency services communicating the identification of a spill. Power analysis showed the system’s ability to remain submerged and to provide surveillance for 100 m sections of a subsea pipeline once every 24 hrs for a month, and can be increased to every hour for 51 months.

Use of a flexible optical fibre bundle to interrogate a Fabry-Perot sensor for photoacoustic imaging.

Photoacoustic imaging systems based on a Fabry Perot (FP) ultrasound sensor that is read-out by scanning a free-space laser beam over its surface can provide high resolution photoacoustic images. However, this type of free-space scanning usually requires a bulky 2-axis galvanometer based scanner that is not conducive to the realization of a lightweight compact imaging head. It is also unsuitable for endoscopic applications that may require complex and flexible access. To address these limitations, the use of a flexible, coherent fibre bundle to interrogate the FP sensor has been investigated. A laboratory set-up comprising an x-y scanner, a commercially available, 1.35 mm diameter, 18,000 core flexible fibre bundle with a custom-designed telecentric optical relay at its distal end was used. Measurements of the optical and acoustic performance of the FP sensor were made and compared to that obtained using a conventional free-space FP based scanner. Spatial variations in acoustic sensitivity were greater and the SNR lower with the fibre bundle implementation but high quality photoacoustic images could still be obtained. 3D images of phantoms and ex vivo tissues with a spatial resolution and fidelity consistent with a free-space scanner were acquired. By demonstrating the feasibility of interrogating the FP sensor with a flexible fibre bundle, this study advances the realization of compact hand-held clinical scanners and flexible endoscopic devices based on the FP sensing concept.

Fiber optic-based laser interferometry array for three-dimensional ultrasound sensing.

Ultrasound imaging has been widely used in medical diagnosis due to its noninvasive, radiation-free, and real-time features. Optical resonance-based ultrasound sensors possess high sensitivity and broad bandwidth, but they need to operate in specific laser wavelengths or angles, which restricts their application in array sensing. Non-resonance-based optical sensing arrays did not perform with sufficient bandwidths or frame rates. Here we propose a fiber optic-based ultrasound sensing array with relatively high sensitivity, wide bandwidth, and three-dimensional (3D) sensing capabilities, which is potentially useful in medical imaging. Specifically, we experimentally demonstrated that the optical ultrasound sensor exhibited a noise equivalent pressure of 165 Pa, pressure nonlinearity of ${\lt 5}\% $<5%, $ - {3}\,\,{\rm dB}$-3dB angular uniformity of $ \pm {71}^\circ ,$±71∘, and $ - {6}\,\,{\rm dB}$-6dB bandwidth from $\sim{0}$∼0 to 27.2 MHz. For 3D sensing capabilities in spherical coordinates, the errors of the radial distance were within 5%, and the errors for the polar and azimuthal angles were within 4° and 2°, respectively. This demonstrated the viability and high performance of the array for 3D ultrasound sensing.

Photoacoustic imaging of the human placental vasculature.

Minimally invasive fetal interventions require accurate imaging from inside the uterine cavity. Twin‐to‐twin transfusion syndrome (TTTS), a condition considered in this study, occurs from abnormal vascular anastomoses in the placenta that allow blood to flow unevenly between the fetuses. Currently, TTTS is treated fetoscopically by identifying the anastomosing vessels, and then performing laser photocoagulation. However, white light fetoscopy provides limited visibility of placental vasculature, which can lead to missed anastomoses or incomplete photocoagulation. Photoacoustic (PA) imaging is an alternative imaging method that provides contrast for hemoglobin, and in this study, two PA systems were used to visualize chorionic (fetal) superficial and subsurface vasculature in human placentas. The first system comprised an optical parametric oscillator for PA excitation and a 2D Fabry‐Pérot cavity ultrasound sensor; the second, light emitting diode arrays and a 1D clinical linear‐array ultrasound imaging probe. Volumetric photoacoustic images were acquired from ex vivo normal term and TTTS‐treated placentas. It was shown that superficial and subsurface branching blood vessels could be visualized to depths of approximately 7 mm, and that ablated tissue yielded negative image contrast. This study demonstrated the strong potential of PA imaging to guide minimally invasive fetal therapies.

Smart Plant Growth Control and Monitoring System for Indoor Hydroponic Farming

Hydroponics is one of planting method that use water as a medium of plants growth, in this technique, mineral solution added into the water solvent, allowing the nutrient uptake process by the plants. Farming by hydroponic method must pay attention to the following parameters namely, temperature, humidity, the level of water needs and nutrients and also the level of sunlight need for photosynthesis process. This research used hydroponic technique in hydroponic growth room, and there is a LED growth light as an alternate of sunlight, due to this room is closed without sunlight. There are outputs displayed in monitoring system namely, temperature sensor, humidity sensor, ultrasound sensor to detect height of the plant and water level sensor to measured height of the water as a medium of the plant. Results of measured sensor in hydroponic growth room explained as the following: fan cooler worked when temperature , and humidity . Water pump worked when water level is less than 50% accordance set point. Control on LED Growth Light and LED Bulb when LDR sensor reached set point &gt; 500 in bright condition, and &lt; 500 in dark condition respectively. The average of Time update/received data in thing speak web is 2.4 second. Keywords: Smart Control, Hydroponic, IoT, Monitoring

Multi-layered domain morphology in relaxor single crystals with nano-patterned composite electrode

(1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT) single crystals, especially with compositions near its morphotropic phase boundary (MPB), have been employed for a broad range of applications such as ultrasound transducers, sensors, and actuators. To further enhance the properties of PMN-PT, electrode patterning, as a method of domain engineering, was proved to be an effective approach. In our previous report, a 200 nm grating pattern electrode (Ti/Au–MnOx) (nano-electrode) was prepared on one surface of PMN-PT crystal, exhibiting 30% d33 enhancement. In this work, the multi-layered domain morphology and the domain engineering from nano-electrode were characterized using piezoresponse force microscopy (PFM). A hypothetical domain engineering model for nano-electrodes is established to explain the experimental results as well as the property enhancement from the nano-electrode. The electrode patterning proves that the nano-scale modification can tune the macro-scale piezoelectric properties of the bulk material.

Dual-Polarized Fiber Laser Sensor for Photoacoustic Microscopy.

Optical resolution photoacoustic microscopy (OR-PAM) provides high-resolution, label-free and non-invasive functional imaging for broad biomedical applications. Dual-polarized fiber laser sensors have high sensitivity, low noise, a miniature size, and excellent stability; thus, they have been used in acoustic detection in OR-PAM. Here, we review recent progress in fiber-laser-based ultrasound sensors for photoacoustic microscopy, especially the dual-polarized fiber laser sensor with high sensitivity. The principle, characterization and sensitivity optimization of this type of sensor are presented. In vivo experiments demonstrate its excellent performance in the detection of photoacoustic (PA) signals in OR-PAM. This review summarizes representative applications of fiber laser sensors in OR-PAM and discusses their further improvements.

Ultrasound as a Tool to Study Muscle–Tendon Functions during Locomotion: A Systematic Review of Applications

Movement science investigating muscle and tendon functions during locomotion utilizes commercial ultrasound imagers built for medical applications. These limit biomechanics research due to their form factor, range of view, and spatio-temporal resolution. This review systematically investigates the technical aspects of applying ultrasound as a research tool to investigate human and animal locomotion. It provides an overview on the ultrasound systems used and of their operating parameters. We present measured fascicle velocities and discuss the results with respect to operating frame rates during recording. Furthermore, we derive why muscle and tendon functions should be recorded with a frame rate of at least 150 Hz and a range of view of 250 mm. Moreover, we analyze why and how the development of better ultrasound observation devices at the hierarchical level of muscles and tendons can support biomechanics research. Additionally, we present recent technological advances and their possible application. We provide a list of recommendations for the development of a more advanced ultrasound sensor system class targeting biomechanical applications. Looking to the future, mobile, ultrafast ultrasound hardware technologies create immense opportunities to expand the existing knowledge of human and animal movement.

Easy on the Ear

Ultrasound sensor aids diagnosis of middle-ear infection

Pulse Pileup Correction of Signals From a Pyroelectric Sensor for Phase-Insensitive Ultrasound Computed Tomography

This paper describes the application of a pulse pileup correction algorithm based on maximum likelihood estimation to simulated and experimentally acquired signals from a pyroelectric ultrasound sensor. The sensor forms part of a prototype phase-insensitive ultrasound computed tomography (piUCT) system for breast cancer detection that generates quantitative maps of acoustic attenuation. The effectiveness of the piUCT technique has been previously demonstrated through imaging of cylindrical, polyurethane phantoms. For the technique to be applied clinically, the system must be capable of measuring high acoustic attenuations (>30 dB) and completing a scan in a clinically acceptable time frame of approximately 5 min. High attenuations present a challenge because the sensor responds directly to acoustic power and therefore, an attenuation of 30 dB causes a drop in signal level of three orders of magnitude, resulting in a large dynamic range in the received signal set. Completion of a scan in 5 min requires a period between measurements shorter than the response time of the sensor, causing pyroelectric pulse pileup. The maximum likelihood estimation method recovers the amplitudes of closely spaced superimposed pyroelectric signals while improving the coefficient of variation of the measurement by a factor of two compared to direct pulse amplitude measurement, simultaneously increasing the maximum measurable attenuation and measurement rate of the system.

Technical and Physical Limitations in the Determination of Background Mercury Concentration

The optical schemes and characteristics of atomic absorption Hg <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sup> analyzers based on the Zeeman effect and a low-pressure capillary mercury lamp, as well as on 190 fm linewidth UV dye laser systems have been studied in detail. The method of evaluating the limit of detection (LOD) of atomic absorption analyzers is proposed. The characteristics of modern ultra-narrowband sensors and sources of UV radiation are analyzed. The efficiency of using new thermal ultrasonic sensors as optical power detectors in the atomic absorption analyzer is discussed. Technical characteristics and reliability of such sensors are compared with all known thermal sensors. The main physical and technical limitations that have a negative effect on the sensitivity and miniaturization of thermal ultrasound sensors are presented. The study shows that such thermal sensors have low sensitivity and accuracy, which makes their use in portable express analyzers of background mercury impractical. The evaluation results prove that the analyzers which use a transverse magnetic field for splitting the lamp emission line also cannot register background mercury concentration. This fact is explained by the low signal-to-noise ratio (SNR) of the discharge low-pressure UV lamp operating in a continuous mode and by the absorption of forbidden oxygen lines by the reference optical signal. The estimation results shown that the portable Hg <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sup> analyzers based on UV dye laser systems can reach the LOD <; 0.1 ng/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . Thus, the main stage in the design of the portable express background mercury analyzers is a measurement of the SNR of UV sources and sensors.

Pyroelectric ultrasound sensor model

Ultrasound is typically measured using phase-sensitive piezoelectric sensors. Interest in phase-insensitive sensors has grown recently, with proposed applications in ultrasound attenuation tomography of the breast. The advantage of phase-insensitive imaging is that it does not suffer from degradation of image quality due to phase-aberration and narrow directional response. A numerical model of a phase-insensitive pyroelectric ultrasound sensor is presented. The model consists of three coupled components run in sequence: acoustic, thermal, and electrical. The acoustic simulation models the propagation and absorption of the incoming ultrasound wave. The negative divergence of the time-averaged acoustic intensity is used as a heat source in the thermal simulation for the time-evolution of temperature in the sensor. Both the acoustic and thermal simulations are performed using the k-Wave MATLAB toolbox with an assumption that shear waves are not supported in the medium. The final component of the model uses a pyroelectric circuit model which outputs the sensor response based on the temperature change in the sensor. The modelled pyroelectric sensor response and directional dependence are compared to empirical data. A physical model for the directionality of the sensor response is then proposed.

Single-pixel camera photoacoustic tomography.

.Since it was first demonstrated more than a decade ago, the single-pixel camera concept has been used in numerous applications in which it is necessary or advantageous to reduce the channel count, cost, or data volume. Here, three-dimensional (3-D), compressed-sensing photoacoustic tomography (PAT) is demonstrated experimentally using a single-pixel camera. A large area collimated laser beam is reflected from a planar Fabry–Pérot ultrasound sensor onto a digital micromirror device, which patterns the light using a scrambled Hadamard basis before it is collected into a single photodetector. In this way, inner products of the Hadamard patterns and the distribution of thickness changes of the FP sensor—induced by the photoacoustic waves—are recorded. The initial distribution of acoustic pressure giving rise to those photoacoustic waves is recovered directly from the measured signals using an accelerated proximal gradient-type algorithm to solve a model-based minimization with total variation regularization. Using this approach, it is shown that 3-D PAT of imaging phantoms can be obtained with compression rates as low as 10%. Compressed sensing approaches to photoacoustic imaging, such as this, have the potential to reduce the data acquisition time as well as the volume of data it is necessary to acquire, both of which are becoming increasingly important in the drive for faster imaging systems giving higher resolution images with larger fields of view.