Sensitive Transducer Research Articles

Optically driven ultra-stable nanomechanical rotor

Nanomechanical devices have attracted the interest of a growing interdisciplinary research community, since they can be used as highly sensitive transducers for various physical quantities. Exquisite control over these systems facilitates experiments on the foundations of physics. Here, we demonstrate that an optically trapped silicon nanorod, set into rotation at MHz frequencies, can be locked to an external clock, transducing the properties of the time standard to the rod’s motion with a remarkable frequency stability fr/Δfr of 7.7 × 1011. While the dynamics of this periodically driven rotor generally can be chaotic, we derive and verify that stable limit cycles exist over a surprisingly wide parameter range. This robustness should enable, in principle, measurements of external torques with sensitivities better than 0.25 zNm, even at room temperature. We show that in a dilute gas, real-time phase measurements on the locked nanorod transduce pressure values with a sensitivity of 0.3%.

Wind tunnel measurement of small values of rolling moment using six-component strain gauge balance

An experimental investigation was conducted to determine the accuracy of the rolling moment measurement in wind tunnel tests. The test was done in a high Reynolds number blowdown wind tunnel in subsonic, transonic and supersonic speed regimes. The rolling moment was measured on a missile model using an internal six-component monoblock strain gauge balance. The balance rolling moment element was designed as a five-bar cage measuring element. The expected rolling moment values in the test were significantly less than the balance rolling moment measuring element full scale. To check the accuracy of the balance measurement, a sensitive one-component transducer was designed and manufactured. In the first phase of the wind tunnel test, rolling moment was simultaneously measured using the balance and the sensitive transducer. Experimental data obtained using the balance was compared with those obtained by the transducer. It is shown that the balance data agree very well with the sensitive one-component transducer data.

Measuring transducer of angular displacements using phase raids of the surface acoustic waves electric field

The phase method for angular displacement unambiguous measurement based on the use of surface acoustic waves (SAW) devices is proposed and theoretically grounded.To eliminate any ambiguity of phase measurements, the construction of acousto-electronic angular displacement transducer using phase incursion of several SAW on the surface of the piezoelectric circular waveguide at different frequencies is proposed. The information parameters that determine the position of SAW receiver are measured at these frequencies.The rating of potential metrological parameters of the 3-frequency angular displacement transducer in the range 0…..360 degrees with the formation of precise, intermediate and rough measurement scales is carried out. The use of phase incursion on the surface of the piezoelectric waveguide electric field of three SAW at different frequencies taking by moving SAW receiver allows to form precise, intermediate and rough measurement scales in accordance with 11, 6 and 5 binary digits representing the measurement results.The experimental test results of models of a 3-frequency generator block, an amplifying-selective block and a 3-frequencies angular displacement transducer containing circular piezoelectric waveguide with a radius of 15 mm based on zinc oxide-fused quartz structure over which displaces a circular sectional SAW receiver are presented. The amplitude of the SAW receiver output signal varies exponentially depending on a gap between the piezoelectric waveguide surface and SAW receiver. It requires high precision of transducer manufacturing to ensure parallel to the acoustic line surface movement of receiver thus eliminating the influence of the phase velocity dispersion of the surface acoustic wave as a result of the SAW receiver electric field perturbation on the accuracy of measurements. Grading characteristics of angular displacement transducer are linear. The coefficients of angular displacement transformation on the precise scales are 0.54, 0.55 and 0.56 electric degrees/arcsec in the central frequencies of 69.52, 70.62 and 71.69 MHz. At the same time, the resolution and angular displacements measurement error on the precise scale are respectively less than 0.5 arcsec and 1.5 arcsec.The test results of model based on piezoelectric waveguide of zinc oxide-fused quartz structure confirm the possibility of creating highly sensitive angular displacements transducers with a resolution and accuracy properties that are close to the parameters of inductosyns, photoelectric transducers and laser interferometers. However, it may have considerably less weight and dimensions, cost and complexity of construction.Ref. 20, fig.6.

Low frequency high sensitive velocity pickup transducer for vertical dynamic balancing machine (VDBM)

ABSTRACTThe measurement of static and dynamic unbalance of satellite is carried out on vertical dynamic balancing machine (VDBM) [1]. The Velocity pickup is a transducer in VDBM, which measures the dynamic velocity due to static and dynamic unbalance and converts mechanical motion into voltage output, which controls measurement sensitivity of machine. In order to improve measurement sensitivity of balancing machine at low spin speed, a new velocity pickup with higher sensitivity is developed. A full scale development model of velocity pickup is developed and tested with VDBM. This paper gives the detailed description about design, analysis and sensitivity measurement of the low frequency high sensitive velocity pickup.

High Quality Factor Graphene-Based Two-Dimensional Heterostructure Mechanical Resonator.

Ultralight mechanical resonators based on low-dimensional materials are well suited as exceptional transducers of minuscule forces or mass changes. However, the low dimensionality also provides a challenge to minimize resistive losses and heating. Here, we report on a novel approach that aims to combine different two-dimensional (2D) materials to tackle this challenge. We fabricated a heterostructure mechanical resonator consisting of few layers of niobium diselenide (NbSe2) encapsulated by two graphene sheets. The hybrid membrane shows high quality factors up to 245,000 at low temperatures, comparable to the best few-layer graphene mechanical resonators. In contrast to few-layer graphene resonators, the device shows reduced electrical losses attributed to the lower resistivity of the NbSe2 layer. The peculiar low-temperature dependence of the intrinsic quality factor points to dissipation over two-level systems which in turn relax over the electronic system. Our high sensitivity readout is enabled by coupling the membrane to a superconducting cavity which allows for the integration of the hybrid mechanical resonator as a sensitive and low loss transducer in future quantum circuits.

Support Vector Machine with Wavelet Decomposition Method for Fault Diagnosis of Tapered Roller Bearings by Modelling Manufacturing Defects

Tapered roller element bearings are generally applied in machines and transmission gearboxes. In manufacturing outer ring, inner ring and the rollers usually suffer damages. It is a challenging task to reveal and classify the defects. This paper presents an efficient method for fault classification by support vector machines. The faults on the bearing parts created by laser beam machine have similar shape and surface topography as the grinding faults from the manufacturing process. Vibration signature is collected by sensitive transducer and high resolution data acquisition unit. A test-rig is constructed to model the circumstances of the operation of the built-in tapered roller bearings. Moreover, test-rig is planned with the aim to mitigate the harmful vibration components from the environment that influence the precision of the vibration measurement. Feature extraction is executed by wavelet decomposition. Decomposition level is determined by FFT considering the structural frequencies of the bearing elements. The proper wavelet is selected by the Energy-to-Shannon Entropy criteria from Daubechies and Symlet wavelet families. The fault classification is done by R Cran software using support vector machine classifiers. Time domain parameters of the vibration signature such as kurtosis, skewness, crest factor and range are provided to the classifier. Classification rates are high enough to ensure the efficiency of the method in all cases in the study.

Experimental studies on the effect of Reynolds and Weber numbers on the impact forces of low-speed droplets colliding with a solid surface

The impact force of low-speed droplets colliding with a solid surface was recorded with an experimental setup involving a highly sensitive piezoelectric force transducer and a high-speed camera recording the droplet shape. Water, ethanol, pure glycerin and aqueous glycerin solutions were used. Experimental results showed that dimensionless force is independent of the Weber number in the experimental range of 68–858 but varies with the Reynolds number. The impact is categorized into three types of processes according to the data on dimensionless peak force against the Reynolds number. The first type is a viscosity-dominated one, in which the Reynolds number ranges between 2.9 and 20. In the second type, transition process, the Reynolds number is in the range of 20–230. In the inertia-dominated type, the Reynolds number is larger than 230. In the viscosity-dominated impact, dimensionless peak force decreases rapidly with increasing Reynolds number, and the effect of viscosity could not be ignored. In the inertia-dominated impact, dimensionless peak force remains constant with varying the Reynolds number, that is, impact force is directly proportional to the product of liquid density, velocity squared and diameter squared but is unaffected by the changes in viscosity and surface tension. Furthermore, the deformation of droplet shape due to oscillation affects the impact force; a small horizontal-to-vertical ratio results in small impact force and vice versa.

Ultrasonic Single Element and Sectorized Array Transducers with Omnidirectional 2D Field Distribution for Non-Contact Human-Machine Interface and Echo-Location

This work discusses the possibilities of some novel applications for the high frequency (200 kHz–500 kHz), high sensitivity (-20 dB– -35 dB) and wide band (> 50 % @ -20 dB) air-coupled transducers that have been used so far for non-destructive testing and materials characterization at CSIC. These applications refer to non-contact human-machine interfaces, gesture recognition and echolocation. Compared with other technologies, the relatively higher frequency and bandwidth permit to achieve better resolution and the higher sensitivity permit to reach longer distances. In addition, this later feature also permits to reduce the number of transducers. This is achieved by using a conical reflector that provides an omnidirectional (2D) acoustic field. Examples of applications and realizations are shown by using single element 250 kHz transducers; and 8-elements 400 kHz sectorized array transducers. This later type of air-coupled array is introduced here for the first time.DOI: http://dx.doi.org/10.5755/j01.eie.23.4.18722

Basic Science Liver

Basic Science Liver

Intensity-based readout of resonant-waveguide grating biosensors: Systems and nanostructures

Resonant waveguide gratings (RWG) − also called photonic crystal slabs (PCS) − have been established as reliable optical transducers for label-free biochemical assays as well as for cell-based assays. Current readout systems are based on mechanical scanning and spectrometric measurements with system sizes suitable for laboratory equipment. Here, we review recent progress in compact intensity-based readout systems for point-of-care (POC) applications. We briefly introduce PCSs as sensitive optical transducers and introduce different approaches for intensity-based readout systems. Photometric measurements have been realized with a simple combination of a light source and a photodetector. Recently a 96-channel, intensity-based readout system for both biochemical interaction analyses as well as cellular assays was presented employing the intensity change of a near cut-off mode. As an alternative for multiparametric detection, a camera system for imaging detection has been implemented. A portable, camera-based system of size 13cm×4.9cm×3.5cm with six detection areas on an RWG surface area of 11mm×7mm has been demonstrated for the parallel detection of six protein binding kinetics. The signal-to-noise ratio of this system corresponds to a limit of detection of 168M (24ng/ml). To further improve the signal-to-noise ratio advanced nanostructure designs are investigated for RWGs. Here, results on multiperiodic and deterministic aperiodic nanostructures are presented. These advanced nanostructures allow for the design of the number and wavelengths of the RWG resonances. In the context of intensity-based readout systems they are particularly interesting for the realization of multi-LED systems. These recent trends suggest that compact point-of-care systems employing disposable test chips with RWG functional areas may reach market in the near future.

Correlation of Transabdominal Ultrasonography and Cystoscopy in Follow-up of Patients with Non-muscle Invasive Bladder Cancer.

Cystoscopy (CS) is considered to be the gold standard in the follow-up of non-muscle invasive bladder cancer. However, CS is invasive, time-consuming, and expensive. On the other hand, modern sensitive transducers have improved the imaging of urinary tract rendering transabdominal ultrasonography (US) more effective in visualizing intraluminal filling defects in the bladder than it was in the past. Twenty-five follow-up patients of low-risk bladder cancer meeting the inclusion and exclusion criteria were included in study. Ultrasonography of the bladder was performed by a single senior radiologist, and subsequently, these patients were subjected to flexible cystoscopy under local anesthesia. Pain score was calculated for each of the cystoscopies done. Findings of transabdominal ultrasound of the bladder were correlated and compared with those of cystoscopy. Subjects with US and/or CS findings suggestive of recurrence underwent transurethral resection of bladder tumor (TURBT) under general anesthesia and confirmation of the bladder carcinoma was achieved by the histopathological examination. Mean patient age was 60.56years with range of 29 to 77years. The sensitivity of modern ultrasonographic techniques was found to be 84.61% with specificity of 91.7% taking flexible cystoscopy as the gold standard for detection of recurrence. The accuracy of US was 88% with positive predictive value of 91.7% and negative predictive value of 84.61%. Technological evolution has improved the accuracy of ultrasonography in diagnosis of bladder carcinoma. It represents a valuable surveillance tool in selected sub group of low risk non-muscle invasive bladder cancer patients.

Highly Sensitive, Durable, and Multifunctional Sensor Inspired by a Spider.

Sensitivity, durability, and multifunction are the essential requirements for a high-performance wearable sensor. Here, we report a novel multifunctional sensor with high sensitivity and durability by using a buckled spider silk-like single-walled carbon nanotubes (SSL-SWNTs) film as the conducting network and a crack-shaped Au film as the sensitive transducer. Its high sensitivity is inspired by the crack-shaped structure of the spider's slit organs, while the high durability is inspired by the mechanical robustness of the spider silk. Similar to the spider's slit organs that can detect slight vibrations, our sensor also exhibits a high sensitivity especially to tiny strain. The proposed quantum tunneling model is consistent with experimental data. In addition, this sensor also responds sensitively to temperature with the sensitivity of 1.2%/°C. Because of the hierarchical structure like spider silk, this sensor possesses combined superiority of fast response (<60 ms) and high durability (>10 000 cycles). We also fabricate a wearable device for monitoring various human physiological signals. It is expect that this high-performance sensor will have wide potential applications in intelligent devices, fatigue detection, body monitoring, and human-machine interfacing.

A Highly Sensitive Transducer for Landslide Monitoring

The paper presents construction details and experimental characteristics of a transducer devoted to measuring soil displacement during landslides. It consists of a flexible rod on which special highly sensitive strain gages are glued so that rod deformation can be accurately measured. Beside its high sensitivity, the transducer is also characterized by the possibility of measuring soil levels displacements in depth, being thus useful for geologists to study the structure and dynamics of such a phenomenon. Article DOI: https://dx.doi.org/10.20319/mijst.2015.11.0111 This work is licensed under the Creative Commons Attribution-Non-commercial 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc/4.0/ or send a letter to Creative Commons, PO Box 1866, Mountain View, CA 94042, USA.

Laser-Scribed Graphene Electrodes for Aptamer-Based Biosensing.

Graphene as a transducer material has produced some of the best-performing sensing approaches to date opening the door toward integrated miniaturized all-carbon point-of-care devices. Addressing this opportunity, laser-scribed graphene (LSG) electrodes are demonstrated here as highly sensitive and reliable biosensor transducers in blood serum analysis. These flexible electrodes with large electrochemical surface areas were fabricated using a direct-write laser process on polyimide foils. A universal immobilization approach is established by anchoring 1-pyrenebutyric acid to the graphene and subsequently covalently attaching an aptamer against the coagulation factor thrombin as an exemplary bioreceptor to the carboxyl groups. The resulting biosensor displays extremely low detection limits of 1 pM in buffer and 5 pM in the complex matrix of serum.

Nitrogen vacancy centers in diamond as angle-squared sensors

Nitrogen-vacancy (NV) centers are defects in diamonds, which, due to their electronic structure, have been extensively studied as magnetic field sensors. Such field detection applications usually employ the NV centers to detect field components aligned with the direction of the internally-defined spin axis of the NV center. In this work we detect magnetic fields which are slightly misaligned with the NV center axis. In particular, we demonstrate that the NV center can measure the square of the angle between the magnetic field and the NV center axis with high sensitivity which diverges as the external field approaches a value pre-defined by the NV center’s internal parameters, in agreement with predictions. These results show that NV centers could be used as sensitive transducers for making quantum nondemolition (QND) measurements on systems such as nanomechanical oscillators.

Core-Shell Super-Spherical Nanoparticles for LSPR-Based Sensing Platforms

Boosted by the progresses in nanooptics, highly sensitive and label-free optical transducers for sensing applications have been proposed over the last years. Among them, plasmonic nanoparticle-based transducers have had a great success because their resonant behavior is extremely sensitive to the changes of the local surrounding environment, being interesting candidates for real-time measurements and diagnoses. Here, we propose the employment of the core-shell super-spherical nanoparticle to design new sensing devices. We demonstrate that, thanks to this particular geometry, a sensor working in the visible spectrum may exhibit a higher sensitivity with respect to all the conventional solutions currently adopted in the field. The analysis is conducted by developing an analytical model for the polarizability of the core-shell super-spherical particle and verified through a proper set of numerical experiments. Finally, the sensing performances of the core-shell super-spherical nanoparticle are discussed and compared with the state-of-the-art optical sensors working in the same frequency range.

A Diaphragm-type Highly Sensitive Fiber Bragg Grating Force Transducer with Temperature Compensation

This paper presents a novel diaphragm-type fiber Bragg grating (FBG) force transducer with a high sensitivity through combining the axial property of the optical fiber and the transverse property of a circular diaphragm. The theoretical model of the presented sensor was derived, and its sensing characteristics were analyzed by numerical simulation and finite element analysis. A specimen of this type of sensor was manufactured with a 0.6mm-thickness diaphragm and a 0.1-ratio of the radius of the hard core and the outer radius of the diaphragm. Experiments were conducted to show that its experimental force sensitivity 441.84 pm/N was consistent with the theoretical value 422.4 pm/N within a working range of 0~4.9 N, which verified the effectiveness of the proposed theoretical model. Moreover, experimentally the designed transducer provided a broad flat frequency range from 0 to 200 Hz and a dynamic resolution of 0.15 mN $\cdot $ (Hz−0.5). The temperature cross-sensitivity of this sensor was suppressed effectively in the range of 16.7 °C~53.6 °C after implementing the temperature compensation. Compared with the existing FBG force sensors, the proposed sensor provided higher and more easily adjustable sensitivity.

Volatile Organic Compounds and Dimethyl Methyl Phosphonate (DMMP) Sensing Properties of the Metal Oxide Functionalized QCM Transducers at Room Temperature

ZnO nanorods were synthesized directly on the mass sensitive transducer elements, namely the quartz crystal microbalance (QCM), by electrochemical deposition techniques. Besides, vanadium pentaoxide (V2O5) thin films were evaporated on the ZnO nanorods using a thermal evaporation system. The fabricated chemical gas sensors were exposed to different levels of various volatile organic compounds (VOCs). The VOCs sensing measurements were realized at room temperature. The application of an additional V2O5 layer on the ZnO nanorods was found to improve the sensing performance of the nanorods. The highest responses were obtained for the analyte DMMP and the DMMP sensitivities of the sensors are at least three times higher than the sensitivities for the other tested VOCs. ZnO nanorods are considered excellent sensing materials on the QCM allowing selective detection of DMMP and other analytes at room temperature.

Piezoresistive Properties of Suspended Graphene Membranes under Uniaxial and Biaxial Strain in Nanoelectromechanical Pressure Sensors.

Graphene membranes act as highly sensitive transducers in nanoelectromechanical devices due to their ultimate thinness. Previously, the piezoresistive effect has been experimentally verified in graphene using uniaxial strain in graphene. Here, we report experimental and theoretical data on the uni- and biaxial piezoresistive properties of suspended graphene membranes applied to piezoresistive pressure sensors. A detailed model that utilizes a linearized Boltzman transport equation describes accurately the charge-carrier density and mobility in strained graphene and, hence, the gauge factor. The gauge factor is found to be practically independent of the doping concentration and crystallographic orientation of the graphene films. These investigations provide deeper insight into the piezoresistive behavior of graphene membranes.

Modeling of Distributed Sensing of Elastic Waves by Fiber-Optic Interferometry.

This paper deals with the transduction of strain accompanying elastic waves in solids by firmly attached optical fibers. Stretching sections of optical fibers changes the time required by guided light to pass such sections. Exploiting interferometric techniques, highly sensitive fiber-optic strain transducers are feasible based on this fiber-intrinsic effect. The impact on the actual strain conversion of the fiber segment’s shape and size, as well as its inclination to the elastic wavefront is studied. FEM analyses show that severe distortions of the interferometric response occur when the attached fiber length spans a noticeable fraction of the elastic wavelength. Analytical models of strain transduction are presented for typical transducer shapes. They are used to compute input-output relationships for the transduction of narrow-band strain pulses as a function of the mechanical wavelength. The described approach applies to many transducers depending on the distributed interaction with the investigated object.