Quartz Transducer Research Articles

Physical description of a viscoelastically loaded AT-cut quartz resonator

In this work, the electrical admittance of this plane-parallel resonator loaded on one face with a viscoelastic medium is described directly in terms of the physical properties of the system. This description is based on the detailed matrix equations for the piezoelectric quartz and includes the piezoelectric effect of the quartz transducer and the shear modulus and viscosity of the overlayer. This physically based analysis has proven invaluable in relating the admittance behavior directly to the materials’ properties. Initial comparisons of the theory with experimental data are given, including the appearance of even harmonics as described by Benes [E. Benes, J. Appl. Phys. 56, 608 (1984)] for the asymmetrically loaded resonator. Additionally, measurements on a series of perfluoropolyether fluids of differing molecular weights indicate that they cannot be described as simple viscous liquids in the MHz range. The assignment of a frequency-dependent viscosity with a relaxation time proportional to the molecular weight resolves some of the discrepancies. Because this study relates the complete admittance spectrum of the loaded resonator to the overlayer material properties, it opens the possibility of studying more than just the changes in resonant frequency. A detailed analysis of the resonance spectrum using an impedance analyzer would provide data which can be fit to the material’s properties and would be particularly helpful with viscoelastic media.

High-resolution acoustic measurements by path length modulation

An acoustic technique is described which permits precise measurement of phase velocity in liquids or gases with high attenuation ( α >10 cm −1) utilizing a thin, variable path length acoustic cavity formed by a quartz transducer and a piezoelectric bimorph. The path length can be changed manually or in feedback where the bimorph motion is driven by the output of a cw spectrometer. Measurement of phase velocity is then simply measurement of cavity size, which is done capacitively to high precision. The path length modulation method can allow absolute measurement of attenuation as well as resolution of ∼10 −5 in phase velocity with a path length as short as 50μ. It is anticipated that this approach can be used successfully to explore regimes of collective modes and pair breaking in superfluid 3He, as well as textural effects in restricted geometries.

Alpha quartz

The history of the use of alpha quartz, SiO/sub 2/, one of the nine forms of silica is sketched, and its structure and crystallography are described. Piezoelectricity, the most important property of quartz from an electrical standpoint, is explained. Processing of quartz crystals to ensure proper operation in circuits is discussed. The two primary types of device made from quartz crystal plates or wafers, the quartz crystal resonator and the quartz transducer, are described.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

STRATIFIED VAPOR EXPLOSION EXPERIMENTS

Abstract An experimental investigation has been conducted on vapor explosions in a stratified contact mode, where the cold liquid and the hot liquid are initially separated by a stable vapor film. A series of experiments were conducted in a narrow, rectangular vessel (20 cm long, 2.54 cm wide, 65 cm high). One face of the vessel wall is made of transparent material for the visual observation using a high speed camera. The explosion is externally triggered at the one end of the vapor film layer by a pressure shock produced by a magnetic hammer. Four quartz pressure transducers are mounted horizontally at the vessel wall. The mechanical energy release is measured by the displacement of a slug which is initially held at the middle of the vessel. The results with water (10 ∼ 85°C) and saturated liquid nitrogen (− 196°C) show that the explosion propagates along the vapor film interface at a speed of 100∼250m/s. The mechanical energy release was up to 33 joules. The variation of the triggering shock pressure re...

Possible observation of chaos in acoustics

Approximately 20 years ago, I observed an acoustic phenomenon that could have been chaos. Not understanding what I was observing, I found that I could maintain experimental conditions to prevent it from occurring. I did so in order to complete the task at hand. The study involved understanding what conditions subharmonics were generated in an ultrasonic standing wave cavity. Two air-backed quartz transducers were placed in a Fabry-Perot configuration with water; one transducer having a resonant frequency of about 1 MHz; the other always being at lower frequency. Their separation was adjustable to be between 5 to 10 cm apart. The 1-MHz transducer was driven with a variable frequency oscillator. At sufficient power and at some driving frequencies, subharmonics were observed both optically and with a piezoelectric transducer. Upon the onset of subharmonics, an optical diffraction pattern displayed lines in between the lines normally observed. A frequency analyzer connected to the piezoelectric transducer showed subharmonics and the corresponding idlers. Under some higher power conditions, the optical pattern became a smear and the frequency analyzer display became uninterpretable. In retrospect, I now believe what I was observing was chaos.

Evaluation of high-intensity therapeutic ultrasound irradiation in the treatment of experimental hepatoma.

A study evaluating the efficacy of high-intensity therapeutic ultrasound (HITU) as a treatment modality in experimental hepatoma is reported. Morris hepatoma (3924) 1 x 10(6) cells were transferred subcutaneously into 40 male ACI rats (weight, 150 to 200 g). Animals were divided into four experimental groups: group 1 (n = 10) consisted of untreated controls; group 2 (n = 10) received intraperitoneal cyclophosphamide 50 mg/kg as a single dose; group 3 (n = 10) underwent HITU only; and group 4 (n = 10) received both chemotherapy (as in group 2) and HITU (as in group 3). HITU was administered with a 5.5-cm diameter 4-MHz quartz transducer creating a continuous wave with 400 W/cm2 focal intensity. The entire tumor was irradiated in 1-mm increments (horizontal and vertical) using treatment cycles of 4 seconds on and 11 seconds off. Total body weight and tumor volume were measured on the day of treatment, and 4 weeks later. At 4 weeks, the animals were killed, the tumor was excised and weighed, and tumor volume was determined. Tumor volume in all treated animals (groups 2, 3 and 4) was significantly smaller than in controls (P less than .001) at 4 weeks, and tumor volume for animals in group 4 was significantly smaller than for those in groups 2 and 3 (P less than .01). These data indicate that HITU significantly reduces tumor size when compared with control rats with Morris hepatoma. A synergistic effect of chemotherapy and HITU was observed and resulted in an enhanced tumor response and reduction of tumor size.(ABSTRACT TRUNCATED AT 250 WORDS)

Electrode shaping to achieve Gaussian ultrasonic field distribution

The electrode shape required to produce a Gaussian electric field distribution at the surface of a transducer was calculated. Such electrodes were made and tried with both quartz and PZT transducers with promising results. These transducers have an advantage over those made by taking advantage of electrical fringing [Breazeale et al., J. Acoust. Soc. Am. 70, 1791–1793 (1981)] in that they do not have the limitation 2 < W/T < 4. Results of measurement of the ultrasonic field produced at 4 MHz by quartz and PZT are given, and application to NDE and acoustical microscopy is considered. [Research sponsored, in part, by UTORNL Science Alliance, A State of Tennessee Center of Excellence. PZT provided by S. Fujishima, Murata Corp.]

Frequency response evaluation of radial artery catheter-manometer systems: sinusoidal frequency analysis versus flush method.

It is well recognized that catheter-manometer systems significantly distort direct radial artery pressure measurements. Sinusoidal frequency analysis and the flush method of assessing the degree of distortion caused by the monitoring system were compared to determine whether these two methods agree in the estimation of natural frequency and damping coefficient. The frequency response of 30 radial artery catheter-manometer systems used for intensive-care unit patients was measured by the flush method and sinusoidal frequency analysis. The monitoring system consisted of a 20-gauge cannula, 150-cm pressure tubing, two plastic stopcocks, a continuous infusion device with fast flush valve, an American Edwards dome, a Hewlett-Packard quartz transducer, and a Hewlett-Packard blood pressure amplifier. Sinusoidal frequency analysis demonstrated second-order underdamped response for all 30 catheter-manometer systems. No secondary resonance peaks were observed up to a frequency of 200 Hz. The measured frequency response demonstrated that the average catheter-manometer system in use in our intensive care unit would cause significant distortion of the radial artery pressure, with the mean natural frequency (fn) of 14.7 +/- 3.7 Hz and the mean damping coefficient (zeta) of 0.24 +/- 0.07. Although the 30 monitoring systems had identical configurations and visible bubbles were carefully removed, a wide range of frequency responses was found (fn = 10.2 to 25.3; zeta = 0.15 to 0.44).(ABSTRACT TRUNCATED AT 250 WORDS)

High-pressure pulsation of central and microvessel pulmonary artery endothelial cells.

We developed an in vitro method of pulsating central and microvessel pulmonary artery endothelial cells that would allow us to study the effects of increased distending pressures over a prolonged period of time. Preservation of the contact-inhibited monolayer was assessed on phase contrast microscopy and, in addition, scanning and transmission electron microscopy (SEM, TEM) were used to determine whether there were alterations in the surface characteristics or intracytoplasmic organelles that suggested cellular damage. The cells used were obtained from Rambouillet lambs, age 3-5 days, anesthetized with halothane and ventilated. The endothelium was harvested from the central pulmonary artery (CPA) by scraping the luminal surface and from the microvessels (MPA) by infusing microcarrier beads 40-140 microns external diameter. After the second passage in culture, the cells were seeded onto the translucent, flexible polyvinylchloride membrane of a transducer dome and grown to confluence. The cell dome was then connected to a blank dome with an attached quartz transducer, to a reservoir, and to stainless steel bellows tubing, all filled with culture medium and affixed to a pulsation generator. By varying the height of the reservoir, the amplitude of excursion of the bellows tubing, and the rate, the cells could be pulsated at a given distending pressure and frequency. Confluent CPA endothelial cells from three lambs and MPA cells from two others were studied after pulsation at both 100/60 and 20/10 mmHg, 60 times/min for 48 h and after nonpulsation. On phase contrast light microscopy and on SEM, the cells remained confluent.(ABSTRACT TRUNCATED AT 250 WORDS)

Motion Behavior of the Needle Thread of A Lockstitch Sewing Machine for Industrial Use

A lock stitch sewing machine for industrial use has been fitted with a quartz transducer and one or two specially designed attachments which analyze the motion of the needle thread to measure the thread dynamic tension of the needle side and the feed lenghth and the feed velocity of the thread at the outlet or the outlet and the inlet of the tension regulator during the sewing operation at about 200 to 2500 rpm.The attachment consists of a rotary angular meter, a rotary encoder a V-pulley. The needle thread was wound around the pulley.Two kinds of sewing experiments were carried out under constant force of 30 g to pull the bobbine thread through the shuttie tension spring.The experimental results are summarized as follows : 1) Motion open angle of the needle thread, θs at the outlet of the thread tension regulator isalmost independent of the sewing speed. Values of the θs range about from 30° to 40°.2) The extent of the motion angle of the thread θs-e expands with the increase of the sewing speed.And, the time required for the motion of the thread becomes short.3) The mean feed velocity of the thread in creases with the increase of the sowing speed.4) From the above results, if the rotational speed of the arm shaft increases, the intermittent supply of needle thread at the inlet of the ten sion regulator will be transformed into the con tinuous supply.5) In the case of high speed sewing, the needle

Temperature dependence of the ultrasonic nonlinearity parameters of NaCl

The ultrasonic harmonic generation technique using a capacitive detector has been used to measure the ultrasonic nonlinearity parameters of sodium chloride single crystals between 300 and 77 K. Since NaCl is a typical ionic crystal, its ordinary elastic constants have been of interest to many physicists. Likewise, its nonlinear properties, its third‐order elastic constants, and their temperature dependence have been of interest to solid‐state theory. However, to date the large thermal expansion coefficient and the fragility of NaCl have thwarted measurement of the temperature dependence of its nonlinearity parameters. Differential expansion between NaCl and a bonded quartz transducer often has resulted in sample cleavage. A special technique for bonding the quartz transducer to the NaCl sample has been developed. With the aid of this technique, ultrasonic nonlinearity parameters of three different oriented samples of NaCl have been measured for the first time in the temperature ranges of 300 to 77 K for the (100) sample, 300 to 100 K for the (110) sample, and 300 to 110 K for the (111) sample. The TOE constant C111 and two combinations of the other TOE constants and their temperature dependence have been obtained. The results are compared with theory describing interatomic forces in alkali halide crystals. (Research supported in part by the ONR and the UT‐ORNL Science Alliance.]

A new simple method of ultrasonic velocity and attenuation measurement in a high absorption liquid

A special technique is developed to find the cycle-for-cycle matching between the two pulses using two transducers. The one-way travel time of ultrasound is determined with an accuracy of several percent of the period of quartz transducer resonance. The results of the technique show the accuracy of the absolute sound velocity of about 1 m/s, in a highly attenuating liquid using 3-MHz transducers separated by 65 mm.

An open-ended photothermal cell for i n v i v o measurements

A new photothermal open-ended cell particularly adapted for in vivo spectroscopic measurements is described. The detector is a transparent LiNbO3 crystal or a crystalline quartz transducer in direct contact with the sample. The cell can be attached to an optical fiber cable for light excitation. The cell has a high signal-to-noise ratio and its frequency variation is proportional to ω−1.16. In vivo and in vitro measurements performed on green leaf and carbon black samples are presented.

Lagrangian analysis. Modern tool of the dynamics of solids

Explosive metal-working, material synthesis under shock loading, terminal ballistics, and explosive rock-blasting, are some of the civil and military fields of activity that call for a wider knowledge about the behavior of materials subjected to strong dynamic pressures. It is in these fields that Lagrangian analysis methods, the subject of this work, prove to be a useful investigative tool for the physicist. Lagrangian analysis was developed around 1970 by Fowles and Williams. The idea is based on the integration of the conservation equations of mechanics using stress or particle velocity records obtained by means of transducers placed in the path of a stress wave. In this way, all the kinematical and mechanical quantities contained in the conservation equations are obtained. In the first chapter the authors introduce the mathematical tools used to analyze plane and spherical one-dimensional motions. For plane motion, they describe the mathematical analysis methods pertinent to the three regimes of wave propagation encountered : the non-attenuating unsteady wave, the simple wave, and the attenuating unsteady wave. In each of these regimes, cases are treated for which either stress or particle velocity records are initially available. The authors insist that one or the other groups of data (stress and particle velocity) are sufficient to integrate the conservation equations in the case of the plane motion when both groups of data are necessary in the case of the spherical motion. However, in spite of this additional difficulty, Lagrangian analysis of the spherical motion remains particularly interesting for the physicist because it allows access to the behavior of the material under deformation processes other than that imposed by plane one-dimensional motion. The methods expounded in the first chapter are based on Lagrangian measurement of particle velocity and stress in relation to time in a material compressed by a plane or spherical dilatational wave. The Lagrangian specificity of the required measurements is assured by the fact that a transducer enclosed within a solid material is necessarily linked in motion to the particles of the material which surround it. This Lagrangian instrumentation is described in the second chapter. The authors are concerned with the techniques considered today to be the most effective. These are, for stress : piezoresistive gauges (50 Ω and low impedance) and piezoelectric techniques (PVF2 gauges, quartz transducers) ; and for particle velocity : electromagnetic gauges, VISAR and IDL Doppler laser interferometers. In each case both the physical principles as well as techniques of use are set out in detail. For the most part, the authors use their own experience to describe the calibration of these instrumentation systems and to compare their characteristics : measurement range, response time, accuracy, useful recording time, detection area... These characteristics should be taken into account by the physicist when he has to choose the instrumentation systems best adapted to the Lagrangian analysis he intends to apply to any given material. The discussion at the end of chapter 2 should guide his choice both for plane and spherical one-dimensional motions. The third chapter examines to what extent the accuracy of Lagrangian analysis is affected by the accuracies of the numerical analysis methods and experimental techniques. By means of a discussion of different cases of analysis, the authors want to make the reader aware of the different kinds of sources of errors that may be encountered. This work brings up to date the state of studies on Lagrangian analysis methods based on a wide review of bibliographical sources together with the contribution made to research in this field by the four authors themselves in the course of the last ten years.

Ultrasonic Spectrometer for Solutions of Biological Material

A new ultrasonic apparatus was developed for relaxation measurements of biological materials, and was equipped with two kinds of electric circuits for the resonance method and the pulse method. The frequency range was extended to the lower side by using concave quartz transducers of 3 MHz. The relative accuracy of the apparatus was better than 5×10-5 for the ultrasonic velocity, and the accuracy of the absorption per wavelength was about 1×10-4 throughout the frequency range from 670 kHz to 35 MHz. The sample volume was 1 ml and the minimum dry weight of biological material for measurements was 1 mg.

Characterization of bone materials as ultrasonic transducers

Physical, dielectric, piezoelectric and electromechanical parameters have been reported for bone and its two major constituents i.e. collagen and apatite, for their characterization as ultrasonic transducer materials. Collagen and apatite have been extracted from full bone using well known methods. These materials have been used to prepare simple disc-shaped test pieces (dimensions: diameter 10 mm and thickness 1.0 ± 0.01 mm). The variation of various electrical parameters with frequency in the region (1–108 MHz) is examined for these materials. These include impedance, phase angle, relative voltage output, quality factor ‘Q’, dielectric constant and resistivity. The data so obtained are compared with those for ceramic and quartz transducers. The observations on impedance, phase and relative voltage output for bone materials indicate that the first resonance peak falls around 56 MHz followed by second and third harmonics around 112 MHz and 168 MHz respectively. A low ‘Q’ value suggests a fairly wide band transducer, while other parameters compare favourably with ceramic and quartz materials. Bone material has also been used to obtain a transducer in the standard configuration and velocity dispersion in the frequency range 1–108 MHz is examined.

PVDF-Transducers for MHZ-Pulse-Echo Attemiatopm Measurements in Metals at Low Temperatures (Advantages and Limits)

Piezoelectric PVDF-foils have been tested as transducers for pulse-echo sound attenuation measurements at 10 to 200 MHz between 4 and 300 K. Their performance is compared with that of quartz transducers. Measurements of dislocation resonance absorption in high-purity copper single crystals are used to demonstrate that the thin foil PVDF transducers, in contrast to quartz transducers, cause no measurable dislocation effects due thermal expansion mismatch between sample and transducer, e.g. during cooling to low temperatures. However, measurements of the frequency dependence of attenua tion show that foil resonance and foil-X/ 4 interference effects have to be considered carefully with respect to measurements of stress amplitude, frequency and temperature dependence of attenuation.

The forces of ankle joint structures during ergometer cycling.

The ankle joint moment, joint compressive force, and Achilles tendon force obtained during ergometer cycling were calculated by using a quartz force-measuring transducer mounted on the pedal. Six healthy subjects rode in 11 different ways at different workloads, pedalling rates, saddle heights, and pedal foot positions. The mean maximum dorsiflexing load moment about the ankle joint during standardized ergometer cycling was calculated to 30.9 nm. The mean ankle joint compressive force and mean Achilles tendon force measured 1008 N (1.4 times body weight) and 762 N (1.1 times body weight), respectively. The ankle joint moment was significantly changed by a change of workload or pedal foot position.

Digital heart rate monitor derived from the arterial pressure pulse

This monitor displays heart rate without the need for electrical contact with the experimental animal. The device uses a quartz pressure transducer connected to an arterial catheter and has a full scale accuracy of ± 3 beats min −1; its range is 0–400 beats min −1. There is an output voltage proportional to heart rate and internal calibration facilities are provided at 60 and 360 beats min −1.

A plano-concave resonator for ultrasonic absorption measurements

A new ultrasonic resonator method is described for measuring absorption in the frequency range 0.1-1.5 MHz in liquids. The method uses a plano-concave resonator with 56 mm diameter which shows high-Q characteristics enabling absorption measurements down to 0.1 MHz to be carried out. A resonance spectrum is detected using Raman-Nath light diffraction instead of the quartz transducer. The results in water and benzene demonstrate the resolution of the apparatus. Absorption spectra of methyl and ethyl formate are presented.