1,721,176 research outputs found
Ultrasound assisted particle and cell manipulation on-chip
Full text linkUltrasonic fields are able to exert forces on cells and other micron-scale particles, including microbubbles. The technology is compatible with existing lab-on-chip techniques and is complementary to many alternative manipulation approaches due to its ability to handle many cells simultaneously over extended length scales. This paper provides an overview of the physical principles underlying ultrasonic manipulation, discusses the biological effects relevant to its use with cells, and describes emerging applications that are of interest in the field of drug development and delivery on-chip.<br/
3D high frame rate flow measurement using a prototype matrix transducer for carotid imaging
No full textTo accurately investigate the state of the carotid artery by the local haemodynamics and motion of the plaque using ultrasound, high-frame rate volumetric imaging is necessary. We have specifically designed a matrix array for this purpose. In this proceeding we will focus on imaging a volumetric flow profile using this matrix. For this purpose, we extend a fast frequency domain vector flow imaging method to 3D and perform measurements on a flow phantom. The results indicate that it is feasible to estimate 3D velocity vectors on a 3D grid using our matrix transducer and the proposed algorithm.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.ImPhys/Acoustical Wavefield ImagingElectronic Instrumentatio
Acoustic Design of a Transducer Array for Ultrasonic Clamp-on Flow Metering
No full textCurrent ultrasonic clamp-on flow meters are based on single-element transducers that require manual calibration by aligning these to a fixed acoustic path. Moreover, the size and operational frequency of the transducers cannot be adapted to the parameters of the pipe and the liquid, which are in practice not precisely known a priory. A set of two transducer arrays could be used to solve these issues. With an array, properties of the pipe and the liquid can be estimated before measuring flow. Furthermore, electronic beam steering can be used for auto-alignment of the acoustic beam, reducing the need for manual calibration. Moreover, an array allows for the use of signal processing to suppress the effects of spurious Lamb waves propagating in the pipe wall. This research work describes the acoustic design process of a transducer array for ultrasonic clamp-on flow measurements for a wide range of conditions. First, performance requirements are defined. Then, the design models are presented, and a step by step process of the acoustic stack design of the transducer array is described. At each design step, material dimensions are optimized to achieve a thickness resonance mode at 1 MHz within a bandwidth of interest between 0.2 MHz and 2 MHz. Finally, the expected performance of the designed array is reported, based on simulation results.Accepted Author ManuscriptImPhys/Acoustical Wavefield ImagingElectronic Instrumentatio
Tracking electromechanical muscle dynamics using ultrafast ultrasound and high-density EMG
No full textCurrent methods to track the progression and evaluate treatment of muscular dystrophies are scarce. The electromechanical delay (EMD), defined as the time lag from muscle electrical activity to motion onset, has been proposed as a biomarker, but provides only limited insight in the pathophysiol-ogy of muscle function. This work proposes and evaluates a novel method to track the propagation of electromechanical waves in muscles, using high density electromyography and ultrafast ultrasound imaging. Muscle contractions in three healthy subjects were evoked by electrical stimulation, and the subsequent propagating action potentials were successfully tracked in all 90 trials. Contractile waves were detected in 83 recordings. Detection rate varied across muscle depth. Mean (SD) velocities for the action potential were 3.71 (0.08) m/s, 4.73 (0.35) m/s and 3.27 (0.09) m/s for participant 1, 2 and 3 respectively. Velocities for the contractile wave were 3.83 (1.07) m/s, 3.32 (0.78) m/s and 3.41 (0.69) m/s for participant 1, 2 and 3 respectively. In conclusion, our technique can track the fast muscular electromechanical dynamics with high spatiotemporal resolution by combining ultrafast ultrasound imaging and high-density electromyography.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.ImPhys/Medical ImagingBiomechatronics & Human-Machine ControlImPhys/Acoustical Wavefield Imagin
Bone Cutting Performance of Ultrasonic Surgical Tools Incorporating PZT Piezoceramic and Mn:PINPMN-PT piezocrystal
Full text linkBolted Langevin-style Transducers (BLT) are widely adopted in ultrasonic surgical devices. A BLT is normally comprised of a stack of piezoelectric Pb(Zrx Ti 1 -x)O 3 (PZT) rings. Recently, piezoelectric single crystal material Mn-doped Pb(In 1/2 Nb 1/2 )O 3 - Pb(Mg 1/3 Nb 2/3 )O 3 - PbTiO 3 (Mn:PIN-PMN-PT) has emerged as a potential alternative, as it simultaneously exhibits high piezoelectric coefficient, dij, electromechanical coupling coefficient, kij, and mechanical quality factor, Qm. A stepped shape horn with a thin and rounded blade is attached to two BLTs, one incorporating piezoceramic and one incorporating piezocrystal material. The full devices were tuned to L2 at 20 kHz. Ex-vivo tissue cutting experimental results show that the Mn:PIN-PMN-PT driven surgical device has consumed more power and has successfully penetrated through the bone. However, the impedance matched PZT device has lost stability as the penetration progressed. This distinction is ascribed to the higher power density of the piezocrystal material
Comparison of Performance of Ultrasonic Surgical Cutting Devices Incorporating PZT Piezoceramic and Mn:PIN-PMN-PT Piezocrystal
Full text linkBolted Langevin-style Transducers (BLT) are widely adopted in ultrasonic surgical devices. A BLT is normally comprised of a stack of piezoelectric Pb(Zr x Ti 1-x )O 3 (PZT) rings. Recently, piezoelectric single crystal material Mn-doped Pb(In 1/2 Nb 1/2 )O 3 -Pb(Mg 1/3 Nb 2/3 )O 3 - PbTiO 3 (Mn:PIN-PMN-PT) has emerged as a potential alternative. Differently from PZT, where a trade-off in material properties is necessary, Mn:PIN-PMN-PT crystal simultaneously exhibits high piezoelectric coefficient, d ij , electromechanical coupling coefficient, k ij , and mechanical quality factor, Q m . As a result of the higher efficiency, lower electromechanical losses and higher energy density of the piezocrystal material, there is potential for designing smaller ultrasonic devices incorporating Mn:PIN-PMN-PT in BLTs. A stepped shape horn with a thin and rounded blade, forming a surgical tip, was tuned to its 1 st longitudinal mode (L1) at around 20 kHz. Equivalent tips were then attached to the two BLTs, one incorporating the piezoceramic and one employing the piezocrystal material. The full devices were therefore tuned to L2 at 20kHz. The two devices were also excited in the L6 mode at around 60 kHz to investigate the frequency effect on the achievable displacement amplitude at the blade tip. Experimental results show that the Mn:PIN-PMN-PT driven surgical device achieved higher displacement amplitude for the same applied voltage, as a result of the higher power density of the piezocrystal material
Can Mn: PIN-PMN-PT piezocrystal replace hard piezoceramic in power ultrasonic devices?
Full text linkMn:PIN-PMN-PT piezocrystal is investigated to determine whether its enhanced energy density makes it a candidate transducer material for power ultrasonics applications. To this end, the electromechanical and vibrational characteristics of a simple configuration of a bolted Langevin transducer (BLT) and then an ultrasonic surgical device, both incorporating Mn:PIN-PMN-PT piezocrystal, are compared with the same transducer configurations incorporating a conventional hard PZT piezoceramic commonly used in high-power ultrasonic transducers. The material properties of Mn:PIN-PMN-PT are determined using a single sample characterisation technique and these are used in finite element analysis (FEA) to design and then fabricate the BLT and ultrasonic surgical device, tuned to the first and second longitudinal modes at 20 kHz respectively. FEA is similarly used for the hard PZT versions. It is found that the superior elastic compliance of Mn:PIN-PMN-PT results in a higher radial piezo-stack deformation than the hard PZT under ultrasonic excitation of the BLT. However, the resulting longitudinal displacement amplitude of the two BLTs and two ultrasonic surgical devices is found to be equal, despite the higher figure of merit (Qk2 eff) of those incorporating Mn:PIN-PMN-PT. The electrical impedance is measured at increasing excitation levels to evaluate the quality factor, Q. It is found that damping in the BLT with hard PZT is negligibly affected in the excitation range considered; however, the BLT incorporating Mn:PIN-PMN-PT exhibits a large reduction in Q. These findings indicate that, for measurements in air, the advantages of the high figure of merit of the piezocrystal material are not realised in a high-power transducer due to significantly increased damping at high excitation levels. To compare the vibrational response of the two ultrasonic surgical devices, L-C electrical impedance matching was implemented to maximise the efficiency of energy transfer from the source to the transducer under load. Results suggest that similar responses occurred for the two surgical devices in cutting tests using a low strength bone mimic material. However, the Mn:PIN-PMN-PT device exhibited better performance in cutting through higher strength ex-vivo chicken femur
Evaluation of PIC 181 and Mn:PIN-PMN-PT Thickness Extensional Rings for Use in Power Ultrasonic Devices for Minimally Invasive Surgery
Full text linkHigh-Q PIC 181 hard piezoceramic and high-k Mn:PIN-PMN-PT piezocrystal thickness extensional rings have been compared for use in the actuation of an ultrasonic scalpel for robotic endo-surgery. Measured material properties have been verified with both finite element analysis and laser vibrometry, to assess the materials' suitability for high power devices. Measured material properties have been verified with both finite element analysis and laser vibrometry, to assess material's suitability for high power devices. Measurements have shown a kt=0.25 and Qm=2200 , and kt=0.62 and Qm=1100 , for PIC 181 and Mn:PIN-PMN-PT respectively. Conventional bolted Langevin-style transducers (BLTs) have been successfully designed and built to resonate at 20 kHz for both piezomaterials. Modal parameters and performance have been modelled in FEA and measured via laser doppler vibrometry. When devices were excited with 50 Vrms at L1 a displacement of: 8 μm and 7 μm was measured for PIC-181 and Mn:PIN-PMN-PT BLTs respectively. Results suggest that a similar resonant frequency can be achieved with a shorter and equally functional device excited by Mn:PIN-PMN-PT piezocrystals
Ultrasonic Surgical Devices Driven by Piezoelectric Tubes
Full text linkMinimally invasive surgery can potentially benefit from the use of ultrasonic devices through their high precision, low force, and tissue selectivity, thus reducing morbidity, recovery time and cost. To facilitate this, miniature ultrasonic surgical tools are required, integrated with flexible surgical robots to guide them to surgical sites inside the body. This paper presents two novel designs of miniature ultrasonic surgical devices excited by a radially polarized piezoelectric tube. One configuration employs the longitudinal mode of the tube and the other uses the breathing mode in a flextensional configuration, to achieve a longitudinal motion of the blade. Experimental results show that the vibration at the tip of the blade of the cymbal end-cap (flextensional configuration) has developed a 4-6 times higher amplitude with the same excitation than the stepped horn (longitudinal configuration), demonstrating potential for using the breathing mode of the piezoelectric tube
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