Influence of water conductivity on the efficiency and the reproducibility of electrohydraulic shock wave generation

Cathignol, D.; Mestas, Jean‐Louis; Gómez, Fernando Álvarez; Lenz, Peter

doi:10.1016/0301-5629(91)90165-s

Cited by 33 publications

(17 citation statements)

References 1 publication

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“…A mobile seat was used to position the patient and to locate the target stone at the generator focus. Later, new shock-wave sources based on different physical principles were developed, e.g., piezoelectric [2], electromagnetic [3], or electroconductive generators [4]. These machines generally include an X-ray and an ultrasonic location system.…”

Section: Introductionmentioning

confidence: 99%

Generation of higher pressure pulses at the surface of piezo-composite materials using electrical pre-strain

Birer

Gholtestani

Cathignol

2004

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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New clinical concepts in lithotripsy demand smaller shock heads. Reducing the size of piezoelectric shock heads requires increasing the surface pressure of each transducer so that the total pressure at the focus remains the same. A new method allowing generation of large surface pressures is described. The hypothesis is that piezoelectric plots in piezo-composite material are more fragile in extension than in compression. For this reason, actuators are mechanically prestressed between two flasks. This method cannot be used for transducers working at high frequencies, such as 0.5 MHz. So we tried to electrically prestrain compressively the piezoelectric material by applying a high-electrical field in the opposite direction of polarization. Three protocols were tested and compared to classically driven transducers. In the first protocol, prestrain is permanently applied, in the second protocol prestrain is applied for 100 s before the compressive impulse, and in the third protocol prestrain is applied for 100 s and followed by a bipolar field that allows the material to be repoled between two successive pulses. With the two first protocols, rapid depoling and repoling in the opposite direction was noticed. Only with the last protocol was it possible to increase the maximum surface pressure. This increase was approximately the same whether the material was hard or soft. Using this protocol, aging tests were conducted on three samples of each kind of material, and a pressure of 4 MPa was obtained over 10 6 shocks. This value seems to be enough to develop a piezoelectric shock-wave generator with a diameter of approximately 20 cm instead of the 45-cm commercially available.

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Section: Introductionmentioning

confidence: 99%

Generation of higher pressure pulses at the surface of piezo-composite materials using electrical pre-strain

Birer

Gholtestani

Cathignol

2004

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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“…A mobile seat was used to position the patient in order to locate the target stone at the generator focus. Later, new shock-wave sources based on different physical principles were developed, e.g., piezoelectric [2], electromagnetic [3], or electroconductive generators [4]. These machines generally include an X-ray and an ultrasonic location system.…”

Section: Introductionmentioning

confidence: 99%

“…These machines generally include an X-ray and an ultrasonic location system. Nowadays, manufacturers are developing simpler, smaller, and cheaper machines, exploiting recent technical advances, e.g., shock-wave heads with enhanced electroacoustic efficiency [5] or reproducibility [4]. It is widely recognized that simpler machines could be designed if the size of the shock-wave generators were reduced.…”

Section: Introductionmentioning

confidence: 99%

Damping, amplitude, aging tests of stacked transducers for shock wave generation

Sferruzza

Birer

Chavrier

et al. 2002

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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New clinical concepts in lithotripsy demand small shock heads. Reducing the size of piezoelectric shock heads will be possible only if the pressure generated at the surface of each transducer can be increased so that the total pressure at the focus remains the same. To solve this problem, different solutions were proposed. For example, it has been demonstrated that piezocomposite material, as opposed to piezoceramic material, allows the generation of a higher surface pressure before breaking, mainly because radial modes are dramatically reduced. In addition, in a previous paper, we showed the feasibility of generating high-pressure pulse waves without increasing the transducer voltage by using sandwiched transducers, which are a stack of two or more transducers. Some discrepancies appeared, however, between the pressure measured at the surface of the front transducer and the arithmetic sum of the pressures generated by each transducer constituting the stack. In fact, development of such stacked transducers capable of generating surface pressures in the range of 2 to 5 MPa is very complex, which may explain why no aging tests have been reported in the literature thus far. In the first part of this paper, we theoretically determine the importance of the electroacoustical coupling between the two transducers on the generated surface pressure. We show that pressure losses due to these electroacoustical couplings are less than 5%. Experimental measurements done on a stacked transducer assembled and tightened in a castor oil-filled tank are in excellent accordance with the theoretical measurements. Using this assembly technique, it was possible to obtain, on average, out of four elements, a pressure of 7.5 MPa for the duration of 4 million shocks, which would allow the treatment of approximately 1000 patients.

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“…The inductors, instead of As well known, shockwave can be produced by the conventional charging resistors, are used to reduce the generation of a dense pulsed discharge plasma channel energy losses during the charge, thus the overall with underwater electrical wire explosion [1-3], which has efficiency is improved. The electrode system is a couple been widely used for various scientific and technological of copper wires with the diameter of 5 mm, which is purposes [4][5][6][7][8] such as demolition and drilling, hydro-immersed in technical water. The electrode gap was acoustics and medicine (kidney stone destruction).…”

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confidence: 99%

Investigation of Shockwave Produced by Large Volume Pulsed Discharge Under Water

Zhang

Namihira

Kiyan

et al. 2005

2005 IEEE Pulsed Power Conference

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parameters and electrode gaps. Moreover, measurement and analysis of pressures of strong shockwaves were In this paper, the measurement and analysis of performed by using FUJI pressure measuring film, FUJI shockwaves generated by pulsed discharge in water are PHOTO FILM CO., LTD, with a wide pressure ranging made with FUJI pressure measuring film. When pressure from 2.5 to 10 MPa. Finally, the electrical discharge is applied, the reaction takes place between the color-parameters and electrode configuration are optimized for forming material and color-developing material coated on maximum energy transformation efficiency into the bases of the film, and color corresponding to the level shockwaves. of pressure is generated. Based on these results the energy transferred to the water and the average pressure of a II. EXPERIMENT AND DIAGNOSTICS shockwave are estimated. In addition, the electrical parameters and electrode configuration are optimized for The experimental set-up and some parameters of the maximum energy transformation efficiency into shock circuit elements are presented in Fig. 1. A Marx generator waves.was used for a high-voltage pulsed power source in our study. These capacitors connected in parallel were

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Influence of water conductivity on the efficiency and the reproducibility of electrohydraulic shock wave generation

Cited by 33 publications

References 1 publication

Generation of higher pressure pulses at the surface of piezo-composite materials using electrical pre-strain

Generation of higher pressure pulses at the surface of piezo-composite materials using electrical pre-strain

Damping, amplitude, aging tests of stacked transducers for shock wave generation

Investigation of Shockwave Produced by Large Volume Pulsed Discharge Under Water

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