Ultrasound Sensor Research Articles

Dispersed Sensing Networks in Nano-Engineered Polymer Composites: From Static Strain Measurement to Ultrasonic Wave Acquisition.

Self-sensing capability of composite materials has been the core of intensive research over the years and particularly boosted up by the recent quantum leap in nanotechnology. The capacity of most existing self-sensing approaches is restricted to static strains or low-frequency structural vibration. In this study, a new breed of functionalized epoxy-based composites is developed and fabricated, with a graphene nanoparticle-enriched, dispersed sensing network, whereby to self-perceive broadband elastic disturbance from static strains, through low-frequency vibration to guided waves in an ultrasonic regime. Owing to the dispersed and networked sensing capability, signals can be captured at any desired part of the composites. Experimental validation has demonstrated that the functionalized composites can self-sense strains, outperforming conventional metal foil strain sensors with a significantly enhanced gauge factor and a much broader response bandwidth. Precise and fast self-response of the composites to broadband ultrasonic signals (up to 440 kHz) has revealed that the composite structure itself can serve as ultrasound sensors, comparable to piezoceramic sensors in performance, whereas avoiding the use of bulky cables and wires as used in a piezoceramic sensor network. This study has spotlighted promising potentials of the developed approach to functionalize conventional composites with a self-sensing capability of high-sensitivity yet minimized intrusion to original structures.

Relationship Between Mechanical Work and Metabolic Cost of Multiple Sets of Resistance Exercise to Failure

Resistance Exercise (RE), due to its short high intensity nature, primarily uses glycolysis; producing more CO2 than utilizing O2. The relationship between Mechanical Work, O2, CO2, and acute muscular fatigue during RE is not well understood. PURPOSE: To investigate the relationship between volume of O2 (VO2), volume of CO2 (VCO2), and total mechanical work (TMW) in response to multiple sets of high intensity (90% 1-RM) 1-Leg Leg Extension (LE) RE completed to failure. METHODS: 25 males, Age=20.3±1.1yrs, BMI=24.2±2.1, BodyFat%=13.7±6.1, volunteered: Day1 included body composition (air-plethysmography) and 1-RM assessment of dominant 1-leg LE; Day2: (≥96 hours later) subjects’ completed multiple sets of 90%1-RM LE Each set was completed to failure; 15-20 seconds later another set to failure was completed. This sequence (sets to failure) continued until a set was composed of < 1 repetition; subjects’ then completed 10 minutes of sitting rest (Post-RE R). Metabolic measures were recorded on a breath-by-breath basis. VO2 and VCO2 were calculated as the sum totals, in ml/min, for the total RE time period (all reps & sets) & Post-RE R. TMW was measured with an ultrasound sensor (distance & time of weight stack movement) and custom-built software. Correlations, Linear Regression, and Min-Max Accuracy were used to assess the relationship between TMW, VO2, and VCO2. RESULTS: Averages and standard deviations for comparison variables of interest: TMW=3491.1±2127.9Nm, VO2=13210.9±2858.5ml/min, VCO2=15407.4±4136.1ml/min, and failure-set=3.1±1.2. Insignificant correlations were found between TMW and VO2 (r=0.28) & TMW and VCO2 (r=0.21). Linear Regressions suggested TMW had little explanatory power for VO2 (p=0.18, AdjR2 = 0.04), and VCO2 (p=0.31, AdjR2 = 0.01). Min-Max Accuracy measures, comparing in-sample predictions (TMW data plugged into Linear Regression Models) to observed values, were 84.5% for VO2, and 79.1% for VCO2. CONCLUSIONS: Weak Correlations and low AdjR2 values suggest very little relationship between TMW and metabolic measures during and following RE. Min-Max Accuracy measures suggest TMW does not predict VO2 & VCO2 well. These results are not unexpected as the work of RE is primarily governed by anaerobic processes and O2 is not the primary energy source for this type and intensity of activity.

Fault detection of ball screw-based electromechanical actuators using electrical, ultrasound and accelerometer sensors

Electromechanical actuators (EMAs) are considered a promising energy-efficient technology for actuating the flight controls of future aircraft. When it comes to aerospace systems, the degradation of EMAs should be checked during regular maintenance events or through condition-based maintenance. Ball bearings have a significant failure rate for flight control EMAs and are usually monitored by vibration noise. A challenge for detecting bearing faults, using state-of-the-art industrial methods, is the presence of a ball-screw mechanism that produces nominal vibration noise similar to that of faulty bearings. No prior research has investigated this problem. This paper explores vibration noise generated from a set of healthy and faulty bearings included in a typical ball-screw EMA. In addition, a method is introduced for evaluating fault diagnosis performance for different time and frequency vibration features. The technique has been validated on an EMA actuator at the German Aerospace Center (DLR).

Non-destructive Testing Robots (NDTBOTs) for In-Service Storage Tank Inspection

Petrochemical storage tanks are generally inspected when the tank is offline mostly to assess the extent of underside corrosion on the tank floor. Emptying, cleaning and opening a tank for inspection takes many months and is very expensive. Inspection costs can be reduced significantly by inserting robots through manholes on the tank roof to perform non-destructive testing. The challenge is to develop robots that can operate safely in explosive and hazardous environments and measure the thickness of floor plates using ultrasound sensors. This paper reports on the development of a small and inexpensive prototype robot (NDTBOT) which is designed to be intrinsically safe for zone zero operation. The robot “hops” across the floor to make measurements, without any external moving parts. The paper describes the design, experimental testing of the NDTBOT and presents results of steel plate thickness measurements made under water.

Thermal annealing and single–domain preparation in tetragonal Pb(In1/2Nb1/2)O3–Pb(Mg1/3Nb2/3)O3–PbTiO3 crystal for electro–optic and non–linear optical applications

The relaxor–PbTiO3 single crystal has attracted extensive attention in ultrasound transducers, sensors, actuators, and optoelectronics devices due to its excellent piezoelectric response and electro–optic properties. Preparation of a single–domain crystal as a critical process for application in electro–optic and non–linear optical devices suffers from serious and inevitable cracking. Therefore, a pre-poling thermal annealing process was suggested to release residual stress from crystal growth and the ferroelectric–paraelectric phase transition, which significantly reduced the chance of cracking. The effect of thermal annealing on dielectric properties, strain behavior, and domain structure were investigated. As a result, a significant increase of the dielectric constant near room temperature was obtained after annealing, which is close to the dielectric constant of the a-oriented domain. The annealed single crystal showed a lower and sharper strain peak at the coercive electric field compared with the unannealed sample, and the 90° domain walls completely vanished, which was verified by optical microscopy. The crack–free single–domain crystal showed excellent optical quality, with high transmittance of approximately 70% in the visible and near–infrared regions, which indicates that this crystal is a promising candidate for applications in electro–optic and non–linear optical devices.

Bi-eddy current sensor based automated scanning system for thickness measurement of thick metallic plates

Generally, the thickness of thick metallic plates is measured by exploitation of some physical phenomenon outside of eddy currents which are naturally limited for thin plates with respect to the skin effect. Indeed, it is the capacitive or ultrasound sensors which are the commonly used for thick plates. This paper proposes an alternative for thickness evaluation of thick metallic plates using eddy currents. The measurement system consists mainly of two eddy current sensors, an impedance analyzer LCR-meter and a personnel computer equipped with the Labview software. The plate we want to measure its thick thickness is placed between the two sensors. The proposed measurement procedure is based on lift-offs evaluation of a bi-eddy current sensor. The system has been verified and validated with success using several thick aluminum plates. The realized experimental setup can be used for online thickness measurement in some industrial applications.

3-D Ultrasound Sensor More Opportunities in Near Field Recognition

3-D Ultrasound Sensor More Opportunities in Near Field Recognition

Validation of an automated system for aliquoting of HIV-1 Env-pseudotyped virus stocks.

The standardized assessments of HIV-specific immune responses are of main interest in the preclinical and clinical stage of HIV-1 vaccine development. In this regard, HIV-1 Env-pseudotyped viruses play a central role for the evaluation of neutralizing antibody profiles and are produced according to Good Clinical Laboratory Practice- (GCLP-) compliant manual and automated procedures. To further improve and complete the automated production cycle an automated system for aliquoting HIV-1 pseudovirus stocks has been implemented. The automation platform consists of a modified Tecan-based system including a robot platform for handling racks containing 48 cryovials, a Decapper, a tubing pump and a safety device consisting of ultrasound sensors for online liquid level detection of each individual cryovial. With the aim to aliquot the HIV-1 pseudoviruses in an automated manner under GCLP-compliant conditions a validation plan was developed where the acceptance criteria—accuracy, precision as well as the specificity and robustness—were defined and summarized. By passing the validation experiments described in this article the automated system for aliquoting has been successfully validated. This allows the standardized and operator independent distribution of small-scale and bulk amounts of HIV-1 pseudovirus stocks with a precise and reproducible outcome to support upcoming clinical vaccine trials.

Gaze Direction based Mobile Application for Quadriplegia Wheelchair Control System

People with quadriplegia recruit the interest of researchers in introducing automated movement systems for adopted special purpose wheelchairs. These systems were introduced for easing the movement of such type of disabled people independently. This paper proposed a comprehensive control system that can control the movement of Quadriplegia wheelchairs using gaze direction and blink detection. The presented system includes two main parts. The first part consists of a smartphone that applies the propose gaze direction detection based mobile application. It then sends the direction commands to the second part via Wi-Fi connection. The second part is a prototype representing the quadriplegia wheelchair that contains robotic car (two-wheel driving car), Raspberry Pi III and ultrasound sensors. The gaze direction commands, sent from the smartphone, are received by the Raspberry Pi for processing and producing the control signals. The ultrasound sensors are fixed at the front and back of the car for performing the emergency stop when obstacles are detected. The proposed system is based on gaze tracking and direction detection without the requirement of calibration with additional sensors and instruments. The obtained results show the superior performance of the proposed system that proves the claim of authors. The accuracy ratio is ranged between 66% and 82% depending on the environment (indoor and outdoor) and surrounding lighting as well as the smart phone type.

Real-time Geographic Information System (GIS) for Monitoring the Area of Potential Water Level Using Rule Based System

Management of water resources based on Geographic Information System can provide substantial benefits to water availability settings. Monitoring the potential water level is needed in the development sector, agriculture, energy and others. In this research is developed water resource information system using real-time Geographic Information System concept for monitoring the potential water level of web based area by applying rule based system method. GIS consists of hardware, software, and database. Based on the web-based GIS architecture, this study uses a set of computer that are connected to the network, run on the Apache web server and PHP programming language using MySQL database. The Ultrasound Wireless Sensor System is used as a water level data input. It also includes time and geographic location information. This GIS maps the five sensor locations. GIS is processed through a rule based system to determine the level of potential water level of the area. Water level monitoring information result can be displayed on thematic maps by overlaying more than one layer, and also generating information in the form of tables from the database, as well as graphs are based on the timing of events and the water level values.

液体绝缘对光纤法布里-珀罗局放超声传感器特性参数影响

液体绝缘对光纤法布里-珀罗局放超声传感器特性参数影响

Development of an ultrasonic device for quality evaluation of yogurt

In this article a possibility of application of the ultrasonic non-contact method for assessing the quality of yogurt was researched. A prediction assessment was made by an ultrasound based on four parameters – pH, conductivity, fat content, and viscosity. An ultrasonic device was developed to determine the parameters of yoghurt by modified ultrasound sensor available commercially. In order to obtain data for post-processing, a software application was designed for recognizing the ultrasonic signal through the image processing and analysis techniques.&lt;br&gt;The developed algorithms and procedures were applied to determine the distance between the object and the sensor, whereby basic physico-chemical parameters of yogurt could be predicted with the lowest relative error. The working distance was 35 cm for the considered system. The survey results show that the parameters fat content, pH, conductivity, and viscosity of yogurt could be predicted by the proposed system for contactless measurement with accuracy of 94-97%.&lt;br&gt;&lt;br&gt;

Position Tracking During Human Walking Using an Integrated Wearable Sensing System.

Progress has been made enabling expensive, high-end inertial measurement units (IMUs) to be used as tracking sensors. However, the cost of these IMUs is prohibitive to their widespread use, and hence the potential of low-cost IMUs is investigated in this study. A wearable low-cost sensing system consisting of IMUs and ultrasound sensors was developed. Core to this system is an extended Kalman filter (EKF), which provides both zero-velocity updates (ZUPTs) and Heuristic Drift Reduction (HDR). The IMU data was combined with ultrasound range measurements to improve accuracy. When a map of the environment was available, a particle filter was used to impose constraints on the possible user motions. The system was therefore composed of three subsystems: IMUs, ultrasound sensors, and a particle filter. A Vicon motion capture system was used to provide ground truth information, enabling validation of the sensing system. Using only the IMU, the system showed loop misclosure errors of 1% with a maximum error of 4–5% during walking. The addition of the ultrasound sensors resulted in a 15% reduction in the total accumulated error. Lastly, the particle filter was capable of providing noticeable corrections, which could keep the tracking error below 2% after the first few steps.

Interrogation of a ring-resonator ultrasound sensor using a fiber Mach-Zehnder interferometer

We experimentally demonstrate an interrogation procedure of a ring-resonator ultrasound sensor using a fiber Mach-Zehnder interferometer (MZI). The sensor comprises a silicon ring resonator (RR) located on a silicon-oxide membrane, designed to have its lowest vibrational mode in the MHz range, which is the range of intravascular ultrasound (IVUS) imaging. Ultrasound incident on the membrane excites its vibrational mode and as a result induces a modulation of the resonance wavelength of the RR, which is a measure of the amplitude of the ultrasound waves. The interrogation procedure developed is based on the mathematical description of the interrogator operation presented in Appendix A, where we identify the amplitude of the angular deflection Φ0 on the circle arc periodically traced in the plane of the two orthogonal interrogator voltages, as the principal sensor signal. Interrogation is demonstrated for two sensors with membrane vibrational modes at 1.3 and 0.77 MHz, by applying continuous wave ultrasound in a wide pressure range. Ultrasound is detected at a pressure as low as 1.2 Pa. Two optical path differences (OPDs) of the MZI are used. Thus, different interference conditions of the optical signals are defined, leading to a higher apparent sensitivity for the larger OPD, which is accompanied by a weaker signal, however. Independent measurements using the modulation method yield a resonance modulation per unit of pressure of 21.4 fm/Pa (sensor #1) and 103.8 fm/Pa (sensor #2).

Ultrasound functional imaging in an ex vivo beating porcine heart platform

In recent years, novel ultrasound functional imaging (UFI) techniques have been introduced to assess cardiac function by measuring, e.g. cardiac output (CO) and/or myocardial strain. Verification and reproducibility assessment in a realistic setting remain major issues. Simulations and phantoms are often unrealistic, whereas in vivo measurements often lack crucial hemodynamic parameters or ground truth data, or suffer from the large physiological and clinical variation between patients when attempting clinical validation. Controlled validation in certain pathologies is cumbersome and often requires the use of lab animals.In this study, an isolated beating pig heart setup was adapted and used for performance assessment of UFI techniques such as volume assessment and ultrasound strain imaging. The potential of performing verification and reproducibility studies was demonstrated. For proof-of-principle, validation of UFI in pathological hearts was examined.Ex vivo porcine hearts (n = 6, slaughterhouse waste) were resuscitated and attached to a mock circulatory system. Radio frequency ultrasound data of the left ventricle were acquired in five short axis views and one long axis view. Based on these slices, the CO was measured, where verification was performed using flow sensor measurements in the aorta. Strain imaging was performed providing radial, circumferential and longitudinal strain to assess reproducibility and inter-subject variability under steady conditions. Finally, strains in healthy hearts were compared to a heart with an implanted left ventricular assist device, simulating a failing, supported heart.Good agreement between ultrasound and flow sensor based CO measurements was found. Strains were highly reproducible (intraclass correlation coefficients >0.8). Differences were found due to biological variation and condition of the hearts. Strain magnitude and patterns in the assisted heart were available for different pump action, revealing large changes compared to the normal condition. The setup provides a valuable benchmarking platform for UFI techniques. Future studies will include work on different pathologies and other means of measurement verification.

Sensing, Measuring and Modelling the Mechanical Properties of Sandstone

We present a hybrid framework for simulating the strength and dilation characteristics of sandstone. Where possible, the grain-scale properties of sandstone are evaluated experimentally in detail. Also, using photo-stress analysis, we sense the deviator stress (/strain) distribution at the micro-scale and its components along the orthogonal directions on the surface of a V-notch sandstone sample under mechanical loading. Based on this measurement and applying a grain-scale model, the optical anisotropy index K 0 is inferred at the grain scale. This correlated well with the grain contact stiffness ratio K evaluated using ultrasound sensors independently. Thereafter, in addition to other experimentally characterised structural and grain-scale properties of sandstone, K is fed as an input into the discrete element modelling of fracture strength and dilation of the sandstone samples. Physical bulk-scale experiments are also conducted to evaluate the load–displacement relation, dilation and bulk fracture strength characteristics of sandstone samples under compression and shear. A good level of agreement is obtained between the results of the simulations and experiments. The current generic framework could be applied to understand the internal and bulk mechanical properties of such complex opaque and heterogeneous materials more realistically in future.

Rapid volumetric photoacoustic tomographic imaging with a Fabry-Perot ultrasound sensor depicts peripheral arteries and microvascular vasomotor responses to thermal stimuli

PurposeTo determine if a new photoacoustic imaging (PAI) system successfully depicts (1) peripheral arteries and (2) microvascular circulatory changes in response to thermal stimuli.MethodsFollowing ethical permission, 8 consenting subjects underwent PAI of the dorsalis pedis (DP) artery, and 13 completed PAI of the index fingertip. Finger images were obtained after immersion in warm (30-35 °C) or cold (10-15 °C) water to promote vasodilation or vasoconstriction. The PAI instrument used a Fabry-Perot interferometeric ultrasound sensor and a 30-Hz 750-nm pulsed excitation laser. Volumetric images were acquired through a 14 × 14 × 14-mm volume over 90 s. Images were evaluated subjectively and quantitatively to determine if PAI could depict cold-induced vasoconstriction. The full width at half maximum (FWHM) of resolvable vessels was measured.ResultsFingertip vessels were visible in all participants, with mean FWHM of 125 μm. Two radiologists used PAI to correctly identify vasoconstricted fingertip capillary beds with 100% accuracy (95% CI 77.2-100.0%, p < 0.001). The number of voxels exhibiting vascular signal was significantly smaller after cold water immersion (cold: 5263 voxels; warm: 363,470 voxels, p < 0.001). The DP artery was visible in 7/8 participants (87.5%).ConclusionPAI achieves rapid, volumetric, high-resolution imaging of peripheral limb vessels and the microvasculature and is responsive to vasomotor changes induced by thermal stimuli.Key points• Fabry-Perot interferometer-based photoacoustic imaging (PAI) generates volumetric, high-resolution images of the peripheral vasculature.• The system reliably detects thermally induced peripheral vasoconstriction (100% correct identification rate, p < 0.001).• Vessels measuring less than 100 μm in diameter can be depicted in vivo.

A Method for Measuring the Directional Response of Ultrasound Receivers in the Range 0.3–80 MHz Using a Laser-Generated Ultrasound Source

A simple method for measuring the directivity of an ultrasound receiver is described. The method makes use of a custom-designed laser ultrasound source which generates a large diameter (>1 cm) broadband monopolar plane wave with a continuous frequency content extending from to . The plane wave is highly uniform in amplitude (±5% over >8 mm) and phase (equivalent to at 80 MHz over ). To measure directivity, the source is rotated around the receiver under test in a compact centimeter-scale setup. To demonstrate the method, it was used to measure the directivity of two broadband small aperture Fabry-Perot ultrasound sensors over an angular range of ±50° at frequencies up to 80 MHz. Measurements were found to be highly repeatable with an estimated typical repeatability <4% in the range of 0.5-25 MHz. Due to the broad bandwidth, large size, and adjustable nature of the source, the method is widely applicable and could aid the characterization of receivers used in medical ultrasound, ultrasonic nondestructive testing. and ultrasound metrology.

Piezoelectric line detector array for photoacoustic tomography

Photoacoustic tomography relies on a dense coverage of the surface surrounding the imaged object with ultrasound sensors in order to enable an accurate reconstruction. A curved arrangement of integrating line sensors is proposed that is able to acquire data for a linear projection image of the absorbed energy density distribution in the object. Upon rotation of the object relative to the array, three-dimensional (3D) images can be obtained.The proposed design is based on the cost-effective piezoelectric polymer film technology with 64 line shaped sensors arranged on a half-cylindrical surface. It is combined with an optical parametric oscillator for the near infrared as a source for laser pulses. Image reconstruction from recorded signals consists of two-dimensional (2D) back projection followed by an inverse Radon transform.The tomograph exhibits a spatial resolution on the order of 200 to 250μm. In a phantom experiment, the steps from acquisition of a single, 2D projection image to a full 3D image are demonstrated. Finally, in vivo projection images of a human finger are shown, revealing the near real-time imaging capability of the device in 2D.

Blood vessel model equipped with ultrasound sensors for evaluation of intravascular treatment

Blood vessel model equipped with ultrasound sensors for evaluation of intravascular treatment