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1.
Jin Ho Jung Ghulam Destgeer Jinsoo Park Husnain Ahmed Kwangseok Park Hyung Jin Sung 《RSC advances》2018,8(6):3206
We propose an acoustic flow switching device that utilizes high-frequency surface acoustic waves (SAWs) produced by a slanted-finger interdigitated transducer. As the acoustic field induced by the SAWs was attenuated in the fluid, it produced an acoustic streaming flow in the form of a pair of symmetrical microvortices, which induced flow switching between two fluid streams in a controlled manner. The microfluidic device was composed of a piezoelectric substrate attached to a polydimethylsiloxane (PDMS) microchannel having an H-shaped junction that connected two fluid streams in the middle. The two immiscible fluids, separated by the PDMS wall, flowed in parallel, briefly came in contact at the junction, and separated again into the downstream microchannels. The acoustic streaming flow induced by the SAWs rotated the fluid streams within the microchannel cross-section, thereby altering the respective positions of the two fluids and directing them into the opposite flow paths. The characteristics of the flow switching mechanism were investigated by tuning the input voltage and the flowrates. On-demand acoustic flow switching was successfully achieved without additional moving parts inside the microchannel. This technique may be useful for fundamental studies that integrate complex experimental platforms into a single chip.Acoustic streaming flow induced by high-frequency surface acoustic waves has been used to switch streams of two immiscible fluids flowing in parallel through a bifurcating microchannel with an H-shaped junction at the centre. 相似文献
2.
Early diagnosis of sepsis is a difficult problem for intensivists and new biomarkers for early diagnosis have been difficult to come by. Here we discuss the potential of adapting a technology from the electronics industry, surface acoustic wave (SAW) sensors, for diagnosis of multiple markers of sepsis in real time, using non-invasive assays of exhaled breath condensate. The principles and advantages of the SAW technology are reviewed as well as a proposed plan for adapting this flexible technology to early sepsis detection. 相似文献
3.
Quartz crystal microbalance (QCM), surface acoustic wave (SAW)-Rayleigh and ZnO based SAW-Love sensors were fabricated and their sensitivity was comparatively analyzed for the quantification of Staphylococcus aureus (S. aureus). The SAW based sensors showed response magnitudes up to three times greater than that of the QCM sensor for the same mass loading of S. aureus. The ZnO nanoparticle-based SAW-Love sensor has a maximum mass loading sensitivity of 328.75 Hz ng−1. The SAW-Love sensor achieved a lower limit of detection of 2 × 103 CFU mL−1 compared to the QCM counterpart (2 × 105 to 2 × 106 CFU mL−1) under the same conditions. The SAW-Love sensor could be used as a disposable chip in micro or ultra-trace accurate diagnosis methods.Quartz crystal microbalance (QCM), surface acoustic wave (SAW)-Rayleigh and ZnO based SAW-Love sensors were fabricated and their sensitivity was comparatively analyzed for the quantification of Staphylococcus aureus (S. aureus). Staphylococcus aureus (S. aureus) is a common human pathogenic bacteria that has a strong potential to cause food poisoning and can cause a wide variety of diseases and infections in humans such as abscesses, pneumonia, meningitis, endocarditis and septicaemia.1–5 Infections caused by this bacteria are contagious and have emerged as being some of the most infectious worldwide.6,7 According to a report by the National Institutes of Health and the Center of Disease Control and Prevention in the United States, S. aureus infects 500 000 people yearly and can cause irreparable damage.4 Currently, S. aureus can be specifically identified by traditional microbiological laboratory procedures. Traditional and standard protocols for the detection and determination of bacteria are normally based on culture and plate counting of the colony,8 the polymerase chain reaction,9,10 ligase chain reaction,11 biochemical and metabolic tests,12 ELISA,13 and so forth. Although these methods are specific and sensitive, the limitations of the high costs, time consuming procedures, expensive laboratory facilities and complex procedures obstructs widespread use of these technologies for clinical diagnosis. Therefore, it is important to develop rapid, simple, low-cost, non-labor intensive and techniques for the detection of pathogenic bacteria to replace these traditional approaches.14,15 Biosensing technology is a rapid and reproducible approach for the detection of pathogens (S. aureus) or toxins and other biomolecules.16,17 Techniques such as surface plasmon resonance (SPR),18 fluorescence,19 quartz crystal microbalance (QCM) with dissipation tracking (QCM-D)14 and electrochemical20 methods have been developed for rapid detection of the S. aureus pathogen. Recently, numerous aptasensors21 have been developed with integrated nano-materials such as graphene oxide (GO), carbon nanotubes (CNTs), gold nanoparticles (AuNPs), and silver nanoparticles (AgNPs). Another novel technique, the surface acoustic wave (SAW) sensor was also developed and has attracted a significant amount of attention in the physical, chemical and biological fields owing to its high sensitivity and lower limit of detection (LoD).22 Current reports have mainly focused on investigating the sensing of bacteria and the sensitive mechanism that is based on organic polymers or a biofunctional group.23,24 However, a few studies have reported SAW sensors based on an inorganic metal oxide sensitive layer that have been used for detection of the S. aureus pathogen.In the present preliminary study, we fabricated QCM, SAW-Rayleigh and ZnO nanoparticle-based SAW-Love sensors for sensing of the S. aureus pathogen and then comparatively evaluated the sensitivity. The ZnO nanoparticles layer was deposited on top of a SAW chip surface by radio-frequency magnetron sputtering. The sensing performance of the ZnO nanoparticle-based SAW-Love sensor was characterized, and good experimental results were obtained.The SAW sensors were fabricated on a ST-cut quartz (42.75°) substrate and an Al thin film with a thickness of 100 nm was evaporated to form the interdigital transducer (IDT) electrodes. The IDT electrodes (Fig. 1c), which had a width of 5 μm were patterned using photo-lithography and wet-etching processes. The transmitting and receiving interdigital transducers (IDTs) consisted of 100 finger pairs with an aperture of 90λ, and the IDT center-to-center separation was 125λ. To fabricate the SAW-Love sensor, a ZnO thin film was deposited on top of the sensor surface by magnetron sputtering. The microstructure and surface morphology of the ZnO film was characterized with scanning electron microscopy (SEM) (Fig. 1d) and atomic force microscopy (AFM) (Fig. 1e), respectively. According to the SEM and AFM images, the ZnO surface presented a uniform granular structure. The particle size was about 30–40 nm, which is conducive to the sensitive adsorption of the measured substance. In order to maintain a minor resonant frequency drop and the excellent nanoparticles surface of the SAW-Love sensors, the prepared ZnO sensitive layer was controlled within a thickness of ∼1 μm.Open in a separate windowFig. 1(a) QCM sensor fabrication. (b) QCM, SAW-Rayleigh and SAW-Love sensors. (c) Image of the IDTs for the fabricated SAW sensor. (d) SEM image of the ZnO film. (e) AFM image of the ZnO film. (f) Schematic diagram of the experimental setup.In addition, the polydimethylsiloxane (PDMS) materials were packaged onto the ZnO surface for aqueous diagnostics. To fabricate the QCM sensor, a 100 nm thick Au film with a 2 nm Cr adhesion film was sputtered onto both sides of an AT-cut quartz substrate, which had a thickness of 167 μm and diameter of 14 mm. The circular electrodes of the QCM (Ø = 5.1 mm) were patterned using two baffle-plate masks as shown in Fig. 1a. The SAW-Rayleigh and SAW-Love sensors demonstrated resonance frequencies of approximately 157 and 155.9 MHz, respectively. On the other hand, the resonance frequency of the QCM sensor was around 9.95 MHz.The sensing surface was purged with dry N2 before testing. The resonant frequency of the sensors with pure water was measured as a reference. S. aureus samples with concentrations ranging from 2 × 103 to 2 × 109 CFU mL−1 were added dropwise (per microliter) onto each sensitive area. For both the QCM and Rayleigh sensors, S. aureus staked-contacts with the QCM gold layer and the Rayleigh delay-line surfaces, respectively. For the Love wave sensors, adhesion or chemical bonding was found to exist between the surface proteins on S. aureus and the surface of the ZnO nanoparticles. The absolute mass sensitivities and relative sensitivities were then studied. The frequency spectra were measured after the liquid had been completely evaporated. Finally, a frequency spectrum analyzer (Agilent 4396B) was used to obtain the frequency signal (Fig. 1f) by stimulation of a signal generator (Agilent E4436B). The frequency changes can be calculated using a PC and a data acquisition system.The QCM sensor was used to test three samples (2 × 109 CFU mL−1 of S. aureus with different volumes: 1, 2 and 3 μL) and the results are shown in Fig. 2a. The initial resonant frequency value of the QCM sensor was 9.945625 MHz, and the resonant frequency values corresponding to the three volume parameters were 9.944375, 9.943750, and 9.943125 MHz, respectively. The corresponding resonant frequency changes were about 1.25, 1.875 and 2.5 kHz, respectively. The resonant frequency of the QCM decreases with an increasing sample volume (equivalent to increasing the mass of S. aureus), and the corresponding insertion loss does not change significantly.Open in a separate windowFig. 2Frequency response magnitude for the sensors with differing amounts of S. aureus mass loading. (a) QCM. (b) SAW-Rayleigh. (c) SAW-Love. (d) Comparison of the frequency change for the three sensors.The initial resonant frequency value of the SAW-Rayleigh sensor was 157.157500 MHz, and the resonant frequency values corresponding to 1, 2, 3 and 4 μL of 2 × 109 CFU mL−1S. aureus were 157.108125, 157.083125, 157.075625, 157.040625 MHz, respectively, as shown in Fig. 2b. The corresponding frequency changes were 49.375, 74.375, 81.875 and 116.875 kHz, respectively. If the loading of S. aureus is increased, the resonant frequency of the Rayleigh wave decreases dramatically, and the corresponding amplitude gradually decreases. For the SAW-Love sensor in particular, the initial resonant frequency was measured at 155.921250 MHz. The responding magnitudes of the SAW-Love sensor varied between 65.75 and 128.75 kHz with S. aureus loading from 1 to 4 μL, as shown in Fig. 2c. As the sample volume increases, the resonant frequency of the SAW-Love wave gradually decreases, and the corresponding amplitude shows a further decreasing trend compared to that of the SAW-Rayleigh sensor.Obviously, under the same sample conditions, the resonance frequency variation for the QCM sensor was much smaller than for the SAW-Rayleigh and SAW-Love wave sensors (Fig. 2d). One of main reasons for the trend observed between the QCM and SAW sensors was the operating frequency of the QCM based sensor was far less than for the SAW sensors. The QCM and SAW sensors have different acoustic propagation modes, the former is a vertical buck-wave mode, while the latter demonstrates a surface acoustic wave. The concept of QCM diagnosis using microspheres has been proven previously,25,26 however, the higher sensitivity of SAW based sensors is required for the detection of nano-scaled species (i.e., viruses or proteins). In addition, the attenuation of the insertion loss corresponding to the resonance frequency measured using the SAW-Love wave sensor under different loadings of S. aureus was larger than that measured for the SAW-Rayleigh, therefore it can be inferred that this result is closely related to differences in the structure and acoustic wave propagation modes.27 The tested results also proved that the SAW-Love wave sensor has a relatively good detection performance. The Love wave is a kind of SAW which propagates in a layered structure. This is different from the commonly used Rayleigh type SAW device, as the performance of a Love wave device depends on the guiding layer, rather than on the IDT and substrate characteristics. For a ZnO/ST-quartz sensor, the concentrated SAW (shear horizontal wave) retains a lower phase velocity in the ZnO guiding layer while the intrinsic Rayleigh wave maintains a faster propagation velocity in the substrate.28–30 A suitable ZnO guiding layer is the key to implementing a SAW-Love wave sensor with a high mass sensitivity.The mass sensitivity of a sensor can be defined as the frequency shift variation due to the mass (Δf/Δm). The amount of S. aureus in 1 μL was 2 × 106, and the corresponding mass per microliter can be calculated as 200 ng. The respective sensitivity values were therefore obtained and was found to be approximately 328.75, 246.88 and 6.25 Hz ng−1 for the SAW-Love, SAW-Rayleigh and QCM sensors respectively. Fig. 3 shows the relative sensitivities (Δf/f0) for different mass loadings. Obviously, the sensitivity of the SAW-Love and SAW-Rayleigh sensors was much higher than that observed for the QCM. Overall, the SAW based sensors had a S. aureus mass loading sensitivity that was up to 30–50 times higher than that observed for the QCM counterpart. The relatively higher operating frequencies of the SAW based sensors enable their greater sensitivity towards the same amount of adsorbed analytes compared to the QCM counterpart. Furthermore, the confinement of more energy on the surface of the substrate, rather than in the bulk, makes the SAW based sensors more sensitive to any surface perturbations.31Open in a separate windowFig. 3Comparison of the quantification mass sensitivity for S. aureus using three sensors.Further studies were carried out to comparatively analyze the LoD performance obtained from the developed QCM and ZnO nanoparticles-based SAW-Love sensors. The tendency for resonant frequency variation for the biosensors operating at various concentrations from 2 × 103 to 2 × 109 CFU mL−1 can be observed in Fig. 4a.Open in a separate windowFig. 4QCM and SAW-Love sensors were used to quantify different concentrations of S. aureus samples. (a) Operating frequency response. (b) Comparison of frequency change for the two sensors.The QCM sensor demonstrated a response to the sample at a higher concentration range of 2 × 108 to 2 × 109 CFU mL−1, while the SAW-Love wave sensor showed a sensitive response at a lower concentration range of 2 × 103 CFU mL−1. It can easily be seen in Fig. 4b that the SAW-Love wave sensor has a significant detection limit of more than 12 kHz at 2 × 103 CFU mL−1, while the QCM sensor had a detection limit of only 35 Hz at 2 × 105 CFU mL−1. The SAW-Love sensor demonstrated a detection limit that was approximately five orders of magnitude lower for S. aureus concentration compared to that of the QCM sensor. The experimental results further confirmed that the QCM design limits its quantification sensitivity in a liquid media environment or lower concentrations of the species to be measured due to the intrinsic resonance frequency. The SAW-Love wave sensor has a high operating frequency and the higher sensitivity demonstrated for the measured substances in trace analysis indicates a great potential for application in biosensing.The recovery performance of the QCM and SAW-Love wave sensors was studied after diagnosis. Sensing chips were rinsed with aqueous ethanol (30%) for 3 min, soaked in pure water for 1 min, and then purged using dry N2 for 3 min. The resonant frequency spectra were measured for both and are shown in Fig. 5.Open in a separate windowFig. 5Recovery characteristics of the operating frequency spectrum for the (a) QCM and (b) SAW-Love sensors.The resonant frequency spectrum of the QCM sensor can be restored to the initial state after the cleaning treatment. However, the frequency spectrum of the SAW-Love sensor was different from the initial curve and this shows that it cannot be completely recovered. The main reason for the opposite recovery behaviors exhibited by the QCM and SAW-Love sensors is the different surface substrates. The contact electrode layer of the QCM sensor is a gold film (detection area), which does not have a sufficient adsorption and/or interaction with S. aureus. However, the ZnO nanoparticle sensitive membrane on the SAW sensor is in direct contact with S. aureus, and the nano-structures of ZnO can facilitate the adsorption of S. aureus, leading to incomplete desorption. In addition, it is easy to form physical and/or chemical adsorption between ZnO and microorganisms, which is not conducive to complete desorption. Although the frequency spectrum of the ZnO nanoparticle-based SAW-Love sensor was difficult to recover owing to its highly sensitive surface of a SAW delay line, SAW-Love chips can be used as disposable chips for nano or ultra-trace species diagnosis as they can be easily produced using micromachining.In summary, QCM, SAW-Rayleigh and ZnO nanoparticle-based SAW-Love chips were microfabricated and their sensitivity and performance was comparatively analyzed for the quantification of S. aureus. The response of SAW sensors was more than three orders of magnitude greater compared with the QCM sensor for the same mass loading of S. aureus. The ZnO nanoparticle based SAW-Love sensor demonstrated the best mass loading sensitivity. In particular, the nano-structural ZnO substrate was proven to have potential for the irreversible absorption of S. aureus. 相似文献
4.
Starritt HC Hoad CL Duck FA Nassiri DK Summers IR Vennart W 《Ultrasound in medicine & biology》2000,26(2):321-333
Magnetic resonance imaging (MRI) has been used to explore acoustic streaming caused in water under ultrasonic exposure conditions similar to those used for diagnostic applications. Streaming was established in an enclosed tube with acoustically transparent end windows, using a pulsed, weakly-focused transducer of acoustic frequency 3.5 MHz. Phase-detection MRI was used to image and quantify streaming profiles in the region of the acoustic focus. Acoustic powers in the range 0.4 mW to 100 mW were used. The sensitivity of the technique enabled streaming velocities down to 0. 1 mm s(-1) to be measured, generated by acoustic power less than 1 mW. In addition, acoustic streaming generated within open meshes with minimum pore dimensions of 3.0 mm and 2.0 mm was measured. The flow velocity in the coarser mesh reached 0.9 mm s(-1) at 95 mW total acoustic power. These observations demonstrate that acoustic streaming is probably a much more general phenomenon in diagnostic ultrasound (ultrasound) than previously recognised. The combination of magnetic resonance and ultrasound shows promise as a diagnostic method for the differentiation of cystic lesions in vivo, and for their characterisation, with sensitivity significantly greater than using ultrasound alone. 相似文献
5.
Jönsson P Sahlstrand-Johnson P Holmer NG Persson HW Jannert M Jansson T 《Ultrasound in medicine & biology》2008,34(2):228-238
No noninvasive methods exist currently with the capability of distinguishing between various stages of a sinus infection. We studied a method based on induced acoustic streaming in the accumulated fluid within the maxillary sinuses. The hypothesis was that acoustic streaming will not be induced at clinically acceptable intensity levels in infectious mucous fluid because of its high viscosity, whereas detected acoustic streaming is a strong indication that the sinus content is a noninfectious serous fluid. As a model, an anthropomorphic sinus phantom with bovine cortical bone to mimic the bone surrounding the maxillary sinus was constructed. Milk (1.5% fat content) was used as model fluid. From fluid and bone attenuation measurements, an ultrasound frequency of about 5 MHz was estimated to produce the highest acoustic streaming in the sinus phantom. Simulations of the acoustic streaming in a sealed cavity also showed that the width of the ultrasound beam should be about half the size of the cavity to optimize the streaming velocity. With a 4.9-MHz continuous-wave transducer operating at a spatial peak temporal average intensity (I(spta)) of 640 mW/cm(2), an acoustic streaming velocity of 0.19 cm/s was generated and detected in the sinus phantom. 相似文献
6.
7.
Accurate differentiation between stagnant blood and soft tissue or clotted and unclotted blood has potential value in managing trauma patients with internal hemorrhage. Determination by regular ultrasound (US) imaging is sometimes difficult because the sonographic appearance of blood, clots and soft tissue may be similar. A hematoma model was developed to investigate the use of acoustic streaming for hematoma diagnosis in an in vivo environment. The results showed that a derated spatial peak temporal average (SPTA) intensity of 30 W/cm(2) was needed to generate color-Doppler-detectable streaming in stirred blood. The streaming velocity increased in proportion to the derated intensity. Streaming was also detected in stagnant blood, but at higher intensities. In clots, streaming was not detected even at high intensities. The streaming detection may be a valuable tool for improving the distinction between liquid blood and clots or soft tissue in hematoma diagnosis. 相似文献
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9.
Arterial wall stiffness can be associated with various diseases. The stiffness of an artery can be measured with the pulse wave velocity (PWV) using the "foot-to-foot" method. However, the foot of the pressure pulse is not very clear, due to reflected waves. The blood pressure pulse generated by the heart is a low frequency wave and its time resolution is low. PWV is an average indicator of artery stiffness between the two measuring positions; therefore, it cannot easily identify local stiffness. In this paper, a sinusoidally modulated force with a high frequency is generated noninvasively on the arterial wall by the radiation force of ultrasound (US). The resulting vibration in the artery is measured with an US Doppler transceiver. The wave velocity in the artery is measured from a wave image obtained by scanning the force transducer and fixing the sensor transducer. Because of the high imposed force frequency, the temporal resolution of this method is much higher than the conventional pressure PWV method. Local wave velocity more than a few millimeters can be measured, which is not possible with the PWV method. 相似文献
10.
Chunhui Li Guangying Guan Fan Zhang Ghulam Nabi Ruikang K. Wang Zhihong Huang 《Biomedical optics express》2014,5(5):1403-1419
Mechanical properties are important parameters that can be used to assess the physiologic conditions of biologic tissue. Measurements and mapping of tissue mechanical properties can aid in the diagnosis, characterisation and treatment of diseases. As a non-invasive, non-destructive and non-contact method, laser induced surface acoustic waves (SAWs) have potential to accurately characterise tissue elastic properties. However, challenge still exists when the laser is directly applied to the tissue because of potential heat generation due to laser energy deposition. This paper focuses on the thermal effect of the laser induced SAW on the tissue target and provides an alternate solution to facilitate its application in clinic environment. The solution proposed is to apply a thin agar membrane as surface shield to protect the tissue. Transient thermal analysis is developed and verified by experiments to study the effects of the high energy Nd:YAG laser pulse on the surface shield. The approach is then verified by measuring the mechanical property of skin in a Thiel mouse model. The results demonstrate a useful step toward the practical application of laser induced SAW method for measuring real elasticity of normal and diseased tissues in dermatology and other surface epithelia.OCIS codes: (240.6690) Surface waves, (280.3375) Laser induced ultrasonics, (350.5030) Phase 相似文献
11.
A new secondary method of determining ultrasound power is presented based on the pyroelectricity of a thin membrane of the piezoelectric polymer, polyvinylidene fluoride (PVDF). In operation, the membrane is backed by a polyurethane-based rubber material that is extremely attenuating to ultrasound, resulting in the majority of the acoustic power applied to the PVDF being absorbed within a short distance of the membrane-backing interface. The resulting rapid heating leads to a pyroelectric voltage being generated across the electrodes of the sensor that, under appropriate conditions, is related to the rate of change of temperature with respect to time. For times immediately after changes in transducer excitation (switching either ON or OFF), the change in the pyroelectric voltage is proportional to the delivered ultrasound power level. This paper describes a systematic evaluation of the measurement concept applied at physiotherapy frequencies and power levels, investigating key aspects such as repeatability, linearity and sensitivity. The research demonstrates the way that heating of the backing material affects the sensor performance, but outlines the potential of the method as a reproducible, rapid, solid-state method of determining power, requiring calibration using a known ultrasound power source. (E-mail: bajram.zeqiri@npl.co.uk). 相似文献
12.
Water transport in vascular plants provides remarkable opportunities for various engineering applications due to its highly efficient and powerless transportability. Several previous studies were conducted to regulate the biological responses of plants using noninvasive audible or ultrasound waves. However, the control mechanism of acoustic stimuli applied to plants has not been investigated yet. Thus, the practical application of these stimuli to real plants still exhibits technological limitations. This study experimentally investigated the effects of surface acoustic wave (SAW) frequency on plant transpiration to understand the acoustic-activated leaf transpiration and utilize the advantages of SAW. We captured consecutive images of the enhanced water transport in the test plant (Epipremnum aureum) by SAW at three different frequencies (10, 15, and 20 MHz). The dye solution at 15 MHz SAW presented the highest intensity value after 40 min of SAW stimulation. The excitation areas for 15 and 20 MHz SAWs were decreased to 42.3% and 22.6%, respectively, compared with that of 10 MHz SAW. The transpiration rates were directly measured to compare water transport enhancement quantitatively when different SAW frequencies were applied to the same plant leaves. The water transport in the leaves was maximized at 15 MHz SAW, regardless of excitation area.Plant leaf transpiration was enhanced with effective use of SAW activation. The effects on leaf transpiration enhancement were analyzed in detail. The results could be applied to regulate temperature and relative humidity effectively. 相似文献
13.
This paper introduces a novel method for measuring the surface temperature of ultrasound transducer membranes and compares it with two standard measurement techniques. The surface temperature rise was measured as defined in the IEC Standard 60601-2-37. The measurement techniques were (i) thermocouple, (ii) thermal camera and (iii) novel infra-red (IR) “micro-sensor.” Peak transducer surface measurements taken with the thermocouple and thermal camera were −3.7 ± 0.7 (95% CI)°C and −4.3 ± 1.8 (95% CI)°C, respectively, within the limits of the IEC Standard. Measurements taken with the novel IR micro-sensor exceeded these limits by 3.3 ± 0.9 (95% CI)°C. The ambiguity between our novel method and the standard techniques could have direct patient safety implications because the IR micro-sensor measurements were beyond set limits. The spatial resolution of the measurement technique is not well defined in the IEC Standard and this has to be taken into consideration when selecting which measurement technique is used to determine the maximum surface temperature. 相似文献
14.
Results from a clinical study are presented, in which ultrasonically-induced acoustic streaming was successfully used to differentiate fluid-filled lesions (cysts) from solid lesions in the breast. In this study, high-intensity ultrasound pulses from a modified commercial scanner were used to induce acoustic streaming in cyst fluid, and this motion was detected using Doppler methods. Acoustic streaming was generated and detected in 14 of 15 simple cysts, and 4 of 14 sonographically indeterminate breast lesions. This lesion differentiation method appears to be particularly suited for diagnosis of small, possibly newer, cysts that appear indeterminate on conventional sonography due to their size. The results indicate that this method would be a useful adjunct to conventional sonography for the purpose of breast lesion classification. 相似文献
15.
Pressure amplitude measurement is important for general research on ultrasound. Because it requires high accuracy, it is usually done using a hydrophone calibrated by an accredited laboratory. In this paper, a method is proposed for estimating the pressure amplitude in the ultrasound field using an uncalibrated single-element transducer and Khokhlov-Zabolotskaya-Kuznetsov simulations of the ultrasound field. The accuracy of the method is shown to be better than 20% for slightly focused and nonfocused transducers. Extending the method to a pulse-echo setup enables pressure measurement of a transducer without the need for an extra transducer or hydrophone. 相似文献
16.
A high performance surface acoustic wave visible light sensor using novel materials: Bi2S3 nanobelts
Chong Li Hao Kan Jingting Luo Chen Fu Jian Zhou Xueli Liu Wen Wang Qiuping Wei Yongqing Fu 《RSC advances》2020,10(15):8936
Low dimensional Bi2S3 materials are excellent for use in photodetectors with excellent stability and fast response time. In this work, we developed a visible light sensor with good performance based on surface acoustic wave (SAW) devices using Bi2S3 nanobelts as the sensing materials. The SAW delay-line sensor was fabricated on ST-cut quartz with a designed wavelength of 15.8 microns using conventional photolithography techniques. The measured center frequency was 200.02 MHz. The Bi2S3 nanobelts prepared by a facile hydrothermal process were deposited onto SAW sensors by spin-coating. Under irradiation of 625 nm visible light with a power intensity of 170 μW cm−2, the sensor showed a fast and large response with a frequency upshift of 7 kHz within 1 s. The upshift of the frequency of the SAW device is mainly attributed to the mass loading effect caused by the desorption of oxygen from the Bi2S3 nanobelts under visible light radiation.A high performance surface acoustic wave visible light sensor with Bi2S3 nanobelts. 相似文献
17.
18.
Ghulam Destgeer Ali Hashmi Jinsoo Park Husnain Ahmed Muhammad Afzal Hyung Jin Sung 《RSC advances》2019,9(14):7916
We present an acoustofluidic method based on travelling surface acoustic waves (TSAWs) to induce self-assembly of microparticles inside a microfluidic channel. The particles are trapped above an interdigitated transducer, placed directly beneath the microchannel, by the TSAW-based direct acoustic radiation force (ARF). This approach was applied to trap 10 μm polystyrene particles, which were pushed towards the ceiling of the microchannel by 72 MHz TSAWs to form single- and multiple-layer colloidal structures. The repair of cracks and defects within the crystal lattice occurs as part of the self-assembly process. The sample flow through the first inlet can be switched with a buffer flow through the second inlet to control the number of particles assembled in the crystalline structure. The constant flow-induced Stokes drag force on the particles is balanced by the opposing TSAW-based ARF. This force balance is essential for the acoustics-based self-assembly of microparticles inside the microchannel. Moreover, we studied the effects of varying input voltage and fluid flow rate on the position and shape of the colloidal structure. The active self-assembly of microparticles into crystals with multiple layers can be used in the bottom-up fabrication of colloidal structures with dimensions greater than 500 μm × 500 μm, which is expected to have important applications in various fields.We present an acoustofluidic method based on travelling surface acoustic waves (TSAWs) for the self-assembly of microparticles inside a microfluidic channel. 相似文献
19.
瞬时波强(WI)曲线的方法学研究及其意义 总被引:3,自引:1,他引:2
目的重点研究WI的方法学问题,期望对WI的临床推广应用有所帮助。方法查阅文献,结合临床的应用体会,从ET与WI技术的关系、多普勒取样门大小、多普勒流速曲线的奈奎斯特现象、时间分辨力、呼吸、血压、心律不齐、心率等9个因素对WI的影响进行方法学研究。结果上述9种因素对wI均有影响:结论WI有两个主要变量,即动脉管壁的波动和管腔内血流流动,在为临床提供大量有用诊断信息的同时,也出现了一些干扰因素,后者可以通过方法学研究加以控制 相似文献
20.
New piezoelectric transducers for therapeutic ultrasound 总被引:3,自引:0,他引:3
Chapelon JY Cathignol D Cain C Ebbini E Kluiwstra JU Sapozhnikov OA Fleury G Berriet R Chupin L Guey JL 《Ultrasound in medicine & biology》2000,26(1):153-159
Therapeutic ultrasound (US) has been of increasing interest during the past few years. However, the development of this technique depends on the availability of high-performance transducers. These transducers have to be optimised for focusing and steering high-power ultrasonic energy within the target volume. Recently developed high-power 1-3 piezocomposite materials bring to therapeutic US the exceptional electroacoustical properties of piezocomposite technology: these are high efficiency, large bandwidth, predictable beam pattern, more flexibility in terms of shaping and definition of sampling in annular arrays, linear arrays or matrix arrays. The construction and evaluation of several prototypes illustrates the benefit of this new approach that opens the way to further progress in therapeutic US. 相似文献